The geology of Svalbard

The Geology of Svalbard

To Svalbard Colleagues

Geological Society Memoirs Series Editor A. J. FLEET

View of Ny-.&lesund settlement seen from the west with three mountain peaks, Tre Kroner, in the distance. The peaks are capped by Carboniferous strata unconformably resting on Early Devonian rocks. They are 30 km distant from the buildings, being foreshortened by the telephoto lens. The glacier from which they emerge as nunataks extends about 15 km nearer. The remaining 15 km just visible is the eastern, inner part of Kongsfjorden. To the right in the foreground is a raised, insulated and heated utiliduct supplying water from a small lake. Photo M. J. Hambrey, CSE 1962 (SP.941e).

View WSW from the old road quay at Ny Alesund, with Scheteligf]ellet in the centre right formed mainly of Carboniferous and Permian strata. Typical low cloud is creeping half way up the mountain from the right. The middle foreshortened low tundra with snow is characteristic raised beach or strandflat topography. The cliffs in the foreground usually about 5-10 m high form the coastline of the shallow bay, Thiisbukta, where in somewhat deeper water motorboats have a sheltered anchorage. The ice in the foreground is 'bay ice', which forms each winter and melts in the early summer. After a hard winter (probably in June) this bay ice is grounded in shallow water at low tide. In a few days it would disintegrate and drift away with tide. Photo M. J. Hambrey (SP631).

The Geology of Svalbard By W. B R I A N H A R L A N D

(University of Cambridge, UK)

Assisted by LESTER M. ANDERSON and DAOUD MANASRAH (CASP, UK) With contributions by NICHOLAS J. BUTTERFIELD (University of Cambridge, UK) ANTHONY CHALLINOR (deceased formerly University of Cambridge, UK) PAUL A. DOUBLEDAY (CASP, UK) EVELYN K. DOWDESWELL (University of Aberystwyth, UK) JULIAN A. DOWDESWELL (University of Aberystwyth, UK) ISOBEL GEDDES (CASP, UK) SIMON R. A. KELLY (CASP, UK) EDA L. LESK (CASP, UK) ANTHONY M. SPENCER (Statoil, Norway) CLARE F. STEPHENS (CASP, UK)

M e m o i r 17 1997 P u b l i s h e d by The G e o l o g i c a l Society London

THE GEOLOGICAL SOCIETY The Society was founded in 1807 as The Geological Society of London and is the oldest geological society in the world. It received its Royal Charter in 1825 for the purpose of 'investigating the mineral structure of the Earth'. The Society is Britain's national society for geology with a membership of around 8000. It has countrywide coverage and approximately 1000 members reside overseas. The Society is responsible for all aspects of the geological sciences including professional matters. The Society has its own publishing house, which produces the Society's international journals, books and maps, and which acts as the European distributor for publications of the American Association of Petroleum Geologists, SEPM and the Geological Society of America. Fellowship is open to those holding a recognized honours degree in geology or cognate subject and who have at least two years' relevant postgraduate experience, or who have not less than six years' relevant experience in geology or a cognate subject. A Fellow who has not less than five years' relevant postgraduate experience in the practice of geology may apply for validation and, subject to approval, may be able to use the designatory letters C Geol (Chartered Geologist). Further information about the Society is available from the Membership Manager, The Geological Society, Burlington House, Piccadilly, London W1V 0JU, UK. The Society is a Registered Charity, No. 210161.

Published by The Geological Society from: The Geological Society Publishing House Unit 7 Brassmill Enterprise Centre Brassmill Lane Bath BA1 3JN UK (Orders: Tel. 01225 445046 Fax 01225 442836) First published 1997 The publishers make no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility for any errors or omissions that may be made. 9 The Geological Society 1998. All rights reserved. No reproduction, copy or transmission of this publication may be made without written permission. No paragraph of this publication may be reproduced, copied or transmitted save with the provisions of the Copyright Licensing Agency, 90 Tottenham Court Road, London W1P 9HE. Users registered with the Copyright Clearance Center, 27 Congress Street, Salem, MA 01970, USA: the item-fee code for this publication is 0435-4052/97/$10.00. British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library.

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Contents

List of figures List of tables List of photographs Preface Acknowledgements Participants Conventions

ix ..~ Xln

5.4

Xln

5.5 5.6 5.7 5.8 5.9

XV

xvii ixx xxi

PART 1 Introduction

CHAPTER 6

CHAPTER 1 SVALBARD 1.1 Geographical names 1.2 Topography and bathymetry 1.3 The physical environment 1.4 The biota 1.5 Political history 1.6 The Spitsbergen Treaty 1.7 Settlements 1.8 Official publications

Northeastern Spitsbergen, Wilhelmoya and Hinlopenstretet Southwestern Nordaustlandet Kong Karls Land (with S. R. A. Kelly) Barentsoya, Edgeoya and Tusenoyane Hopen Correlation of four exploratory wells: Edgeoya and Hopen

3 7 8 10 11 11 13 13

6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8

Early work Stratal succession Subjacent metamorphic complex Late tectonic plutons Minor igneous bodies Summary of isotopic ages Structure of Nordaustlandet The Lomonosov Ridge in relation to Nordaustlandet

CHAPTER 7 CHAPTER 2 2.1 2.2 2.3 2.4 2.5 2.6

Early exploration 1858 to 1920 1920 to 1945 1946 to 1960 1960 to 1975 1975 onwards

CHAPTER 3 3.1 3.2 3.3 3.4 3.5

CHAPTER 4

4.4 4.5 4.6 4.7 4.8 4.9

16 16 16 18 19 20 21 23 23 25 29 31 37

Regional descriptions THE CENTRAL BASIN

Geological frame Van Mijenfjorden Group (Paleogene) Adventdalen Group (Cretaceous-Jurassic) (by S. R. A. Kelly) Kapp Toscana and Sassendalen Groups (Liassic-Triassic) (with I. Geddes) Biinsow Land Supergroup (Permian-Carboniferous) Tempelfjorden Group (Permian) with I. Geddes & P.A. Doubleday Gipsdalen Group (Permian-Carboniferous) with I. Geddes & P. A. Doubleday Billefjorden Group (Early Carboniferous) with I. Geddes & P. A. Doubleday Structure and development of Central Basin

CHAPTER 5 5.1 5.2 5.3

SVALBARD'S G E O L O G I C A L F R A M E

The space frame: Svalbard's structural frame The time frame The rock frame Tectonostratigraphic sequences Geotectonic interpretations

PART 2 4.1 4.2 4.3

OUTLINE HISTORY OF G E O L O G I C A L RESEARCH

EASTERN SVALBARD P L A T F O R M

Platform strata Igneous rocks Submarine outcrops

7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10

NORTHERN NORDAUSTLANDET

N O R T H E A S T E R N SPITSBERGEN

Geological frame Younger (cover) rocks Post-Permian deformation Ny Friesland plutons The Hecla Hoek Complex: the continuing debate Hinlopenstretet Supergroup Lomfj orden Supergroup Stubendorffbreen Supergroup: succession Stubendorffbreen Supergroup: genesis The Hecla Hoek Complex: mid-Paleozoic structure and metamorphism

77 80 83 86 91 93

96 96 96 104 105 106 106 107 108

110 110 112 112 112 113 116 118 121 125 128

CHAPTER 8 N O R T H W E S T E R N SPITSBERGEN

132

8.1 8.2 8.3 8.4 8.5 8.6

133 134 135 142 145 152

Cenozoic volcanic rocks of the Woodfjorden area Mesozoic, Permian and Carboniferous cover Liefde Bay Supergroup (Devonian) The 'crystalline' rocks of Northwestern Spitsbergen Structure Offshore geology (with P.A. Doubleday)

47 47 48 52 59 63 63 66 71 73 75 75 76 76

CHAPTER 9 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.10

Paleogene strata Mesozoic strata of Oscar II Land Late Paleozoic strata of Oscar II Land Early Paleozoic rocks Proterozoic strata of Oscar II Land Pre-Carboniferous rocks of Prins Karls Forland Structure of Oscar II Land (with P. A. Doubleday) Structure of Prins Karls Forland Structure of Forlandsundet Basin (with P. A. Doubleday) A tectonic interpretation of the West Spitsbergen Orogen: northern segment

CHAPTER 10 10.1 10.2

CENTRAL WESTERN SPITSBERGEN

SOUTHWESTERN A N D S O U T H E R N SPITSBERGEN

Paleogene strata Mesozoic strata in southwest Sorkapp Land

154 154 158 159 162 165 166 168 171 175 177

179 180 182

vi 10.3 10.4 10.5 10.6 10.7 10.8 10.9 10.10 10.11 10.12 10.13

CONTENTS Permian and Carboniferous strata of southern Spitsbergen Devonian strata Proterozoic strata of western Nordenski61d Land Proterozoic strata of western Nathorst and northwestern Wedel Jarlsberg Lands Early Paleozoic and Proterozoic strata of southwestern Wedel Jarlsberg Land Early Paleozoic and Proterozoic strata of Sorkapp Land Pre-Devonian correlation through southwest Spitsbergen Structure of western Nordenski61d Land Structure of western Nathorst Land Structure of Wedel Jarlsberg Land (with P. A. Doubleday) Structure of Sorkapp Land (with P. A. Doubleday)

CHAPTER 11

S O U T H E R N SVALBARD: BJORNOYA A N D SUBMARINE G E O L O G Y

11.1 11.2 11.3 11.4

Early work Geologic frame of Bjernoya Triassic strata of Bjornoya Late Paleozoic strata of Bjornoya (with I. Geddes) 11.5 Pre-Devonian strata of Bjornoya 11.6 Structural sequence of Bj~rnoya 11.7 Submarine outcrops 11.8 Submarine structure (with P. A. Doubleday)

PART 3

199 200 201

CHAPTER 17

201 205

~-~,~~,' nn 210 212 212 213 218 219 222 222

229 229 231 235 236 239 240

Vendian Vendian Vendian Vendian Vendian Vendian

time scale and correlation successions and correlation in Svalbard biotas environments international correlation palinspastic discussion C A M B R I A N - O R D O V I C I A N HISTORY

Cambrian-Ordovician Cambrian-Ordovician Cambrian-Ordovician Cambrian-Ordovician Cambrian-Ordovician

CHAPTER 15

time scale biotas and correlation sedimentary environments tectonic environments terranes and palinspastics

S I L U R I A N HISTORY

15.1 Silurian time 15.2 Silurian supracrustal events: sedimentation and tectonics 15.3 Silurian tectogenesis 15.4 Silurian petrogenesis of crystalline rocks 15.5 Silurian terranes, provinces and palinspastics 15.6 Sequence of Silurian (main Caledonian) events

17.1 17.2 17.3 17.4 17.5

244 244 246 248 249 252 254 257 260 260 264 266 268

17.6 17.7 17.8

D E V O N I A N HISTORY

Devonian time scale and correlation Devonian succession Devonian biotas ?Silurian and Devonian sedimentation Devonian tectonics The question of sinistral Paleozoic strike-slip faulting, transpression and transtension Sequence of events through Devonian time A Lomonosov conjecture

197

Precambrian time scales Pre-Vendian rock successions Pre-Vendian biotas (by N. J. Butterfield) Precambrian isotopic ages Tectonostratigraphic evidence for proto-basement Pre-Vendian correlation Palinspastic considerations V E N D I A N HISTORY

16.1 16.2 16.3 16.4 16.5 16.6 16.7 16.8

227

CHAPTER 14 14.1 14.2 14.3 14.4 14.5

191

PRE-VENDIAN HISTORY

CHAPTER 13 13.1 13.2 13.3 13.4 13.5 13.6

189

Historical Synthesis

CHAPTER 12 12.1 12.2 12.3 12.4 12.5 12.6 12.7

CHAPTER 16 183 187 188

CARBONIFEROUS-PERMIAN HISTORY

Early work Stratigraphic frame: Biinsow Land Supergroup Structural frame Carboniferous and Permian time scale Carboniferous-Permian sedimentary environments {1.~r, I . f"L~,..1,-.l~'~ ~ ,_,y ,_,~uu~) Carboniferous-Permian fossil record Carboniferous-Permian tectonic control of sedimentation (with I. Geddes) Carboniferous and Permian palaeogeology

289 289 291 291 296 299 303 306 309

310 310 312 314 316 318 324 328 335

CHAPTER 18 TRIASSIC HISTORY

340

18.1 18.2 18.3 18.4

340 343 344

18.5 18.6 18.7

Early work Structural frame Triassic rock units Triassic time scale and international correlation (with I. Geddes) Triassic biotas Sequence of Triassic environments (with I. Geddes) Triassic regional palaeogeology

350 353 356 36l

CHAPTER 19 J U R A S S I C - C R E T A C E O U S HISTORY

363

19.1 19.2 19.3 19.4

363 365 366

19.5 19.6 19.7 19.8

Early work Jurassic-Cretaceous structural frame stratigraphic scheme Jurassic-Cretaceous time scale and correlation (with S. R. A. Kelly) Jurassic-Cretaceous formations Jurassic-Cretaceous biotas Jurassic-Cretaceous events in Svalbard events (with S. R. A. Kelly) Svalbard in a Jurassic-Cretaceous regional context

CHAPTER 20 20.1 20.2 20.3 20.4 20.5 20.6 20.7 20.8 20.9

P A L E O G E N E HISTORY

Early work Structural and stratigraphic frame Paleogene time scale and correlation Paleogene biotas of Svalbard Paleogene sedimentation and tectonics Paleogene structures (with A. Challinor & P. A. Doubleday) Structural sequence Regional tectonic sequence Paleogene tectonosedimentary history

368 372 378 381 383 388 388 390 391 393 394 399 410 413 413

272 272 275 275 280 284 288

CHAPTER 21 21.1 21.2 21.3 21.4

N E O G E N E - Q U A T E R N A R Y HISTORY

Neogene--Quaternary time scale Plate motions (by C. F. Stephens) Deep structure of Svalbard Neogene-Holocene volcanism and thermal springs (by C.F. Stephens)

418 418 418 421 423

CONTENTS 21.5 21.6 21.7 21.8 21.9

Neogene and Pleistocene sedimentation (with C.F. Stephens) Neogene-Holocene uplift and erosion Glacial history of Svalbard: Neogene-Holocene (with C.F. Stephens) Pleistocene and Holocene surficial geology and geomorphic features Post-glacial sea-level and climatic changes

CHAPTER 22

22.1 22,2 22,3 22.4 22,5 22,6 22.7

PART 4 426 427 429 431 434

M O D E R N GLACIERS A N D CLIMATE C H A N G E (by E. K. Dowdeswell and J. A. Dowdeswell) 436

Introduction Modern ice cover Geophysical characteristics and ice dynamics Ice-ocean interaction Late Holocene glacial events and chronology Glaciers and climatic change Summary and conclusions

vii

436 436 438 442 443 444 445

23 23.1 23.2 23.3 23.4

APPENDIX: ECONOMIC G E O L O G Y Coal Petroleum (with A. M. Spencer) Metalliferous minerals Non-metalliferous minerals

449 449 251 253 254

I N D E X OF PLACE NAMES (by L. M. Anderson)

455

GLOSSARY OF S T R A T I G R A P H I C NAMES

463

REFERENCES

477

GENERAL INDEX

515

Figures Fig. 4.10 Geological map of Btinsow Land showing the distribution of Permo-Carboniferous formations (Btinsow Land Supergroup) Fig. 4.11 Summary of the stratigraphic schemes for Central Spitsbergen since 1950 Fig. 4.12 Schematic west-east stratigraphic profile showing lateral variations and structural controls on Carboniferous stratigraphy Fig. 4.13 Stratigraphic schemes for the Billefjorden Group Fig. 4.14 Simplified structural cross-sections of the Central Basin

CHAPTER 1 Fig. 1.1 Regional geographical setting of Svalbard Fig. 1.2 Principal islands and fjords of Svalbard Fig. 1.3 The 'lands' of Svalbard Fig. 1.4 Map showing the principal topographic features of Svalbard Fig. 1.5 Bathymetry of the western Barents Shelf Fig. 1.6 Prevailing surface currents of the Barents Sea and North Atlantic areas Fig. 1.7 Principal ice cover and valleys of Svalbard Fig. 1.8 Diagrammatic map to show boundaries of possible political interest Fig. 1.9 Map showing environmentally protected areas of Svalbard Fig. 1.10 Marine chart sheet coverage of Svalbard Fig. 1.11 Topographic and geological map coverage of Svalbard

12 12 14

Fig. 3.1 Svalbard in the Arctic (Polar projection) 23 Fig. 3.2 Generalized geological map of Svalbard 24-5 Fig. 3.3 Regions of Svalbard as used in this book for Chapters 4 to 11 25 Fig. 3.4 Principal discontinuities in Svalbard 26 Fig. 3.5 Major structural features of the western Barents Shelf 26 Fig. 3.6 Russian structural map of Svalbard 27 Fig. 3.7 Provisional time scale used in this book 28 Fig. 3.8 Svalbard chronometric record 30 Fig. 3.9 Tectonostratigraphic terranes of Svalbard 32 Fig. 3.10 (a) Simplified stratigraphy and geological evolution of Svalbard 39 (b) Schematic map of rock units and terranes 40 Fig. 3.11 Sequence of palinspastic reconstructions for the North Atlantic and Arctic from Cambrian to the present-day 41-2 Fig. 3.12 Summary of successive palaeolatitudes for Europe and North America for Silurian to Neogene time 43 Fig. 3.13 Plot of subsidence against time for western, central and eastern areas 44 CHAPTER 4

CHAPTER 6

CHAPTER 2 Fig. 2.1 Geological sketch map of Spitsbergen by A. G. Nathorst Fig. 2.2 Geological map of Spitsbergen by Hans Frebold

17 19

CHAPTER 3

Fig. 4.1 Reproduction of the Festningen profile as by Hoel & Orvin (1937) Fig. 4.2 Map of the Paleogene outcrops in the Central Basin Fig. 4.3 Stratigraphy of the Van Mijenfjorden Group Fig. 4.4 Geological map and cross-section of eastern Nordenski61d Land and Sabine Land Fig. 4.5 Geological map of the east coast of Spitsbergen from Agardhbukta to Hamburgfjellet Fig. 4.6 Geological map and cross sections of the Adventdalen Group in Wedel Jarlsberg Land and western Torell Lands Fig. 4.7 Geological map and cross sections of the Adventdalen Group in Sorkapp Land Fig. 4.8 Geological map and cross sections of the Adventdalen Group in Oscar II Land, Nordenski61d Land and Nathorst Land Fig. 4.9 Fence diagram showing the distribution and thickness variation of the Sassendalen and Kapp Toscana groups

49 50 51 54 55

56 56

58 60

65

66 72 73

CHAPTER 5 Fig. 5.1 Map of the eastern platform area of Svalbard showing the main place names and principal bathymetric features Fig. 5.2 Geological map of eastern Ny Friesland Fig. 5.3 Geological map of southwestern Nordaustlandet showing the known extent of Phanerozoic outcrops Fig. 5.4 Stratigraphical schemes for Permian and Triassic units of Nordaustlandet Fig. 5.5 Sketch map of Svenskoya, Kongsoya and Abeloya Fig. 5.6 Sketch map of Svenskoya showing principal topographic features and geology Fig. 5.7 Sketch map of Kongsoya showing principal topographic features and geology Fig. 5.8 Summary of schemes of rock units, and their ages, of Kong Karls Land Fig. 5.9 Correlation of the principal stratigraphic sections on Svenskoya Fig. 5.10 Correlation of the principal stratigraphic sections on Kongsoya Fig. 5.11 Proposed nomenclature for local rock units on Barentsoya and Edgeoya Fig. 5.12 Geological map of Barentsoya and Edgeoya Fig. 5.13 Interpretation of Raddedalen- 1 well (Edgeoya) Fig. 5.14 Interpretation of Plurdalen-1 well (Edgeoya) Fig. 5.15 Edgeoya and Barentsoya Triassic biostratigraphy Fig. 5.16 Generalized structural map of Barentsoya and Edgeoya, with structure contours for the top of the Barentsoya Formation Fig. 5.17 Geological map of Hopen and a longitudinal section along the island Fig. 5.18 Interpretation of Hopen-1 and Hopen-2 wells Fig. 5.19 Correlation of the Raddedalen-1, Plurdalen- 1, Hopen-1 and Hopen-2 wells

14

64

Fig. 6.1 Map of northern Nordaustlandet showing principal topographic features, ice-rock boundaries and major place names Fig. 6.2 Preferred names for rock units in Nordaustlandet and their approximate equivalents in Ny Friesland, with estimated thicknesses Fig. 6.3 Geological map of northwestern Nordaustlandet Fig. 6.4 Summary of isotopic ages from Nordaustlandet Fig. 6.5 Outline geological map of Nordaustlandet and adjacent areas of Ny Friesland

76 78 80 81 82 82 83 84 84 85 87 88 90 91 91

92 92 94 95

97

98 101 107 108

CHAPTER 7 Fig. 7.1 Topographic and place name map of Ny Friesland Fig. 7.2 Summary of the Hecla Hoek succession of Ny Friesland. Fig. 7.3 Generalized geological map of Ny Friesland outlining the distribution and subdivision of the Hecla Hoek Complex

111 114

115

x Fig. 7.4 Distribution of the Stubendorffbreen Supergroup in Ny Friesland Fig. 7.5 (a) Metamorphic rocks of the southern part of Ny Friesland (Lower Hecla Hoek) (b) M.B. Bayly's metamorphic zones as defined in Ny Friesland Fig. 7.6 Structural map of Ny Friesland Fig. 7.7 Diagrammatic cross-sections across Ny Friesland Fig. 7.8 Alternative structural interpretations across Ny Friesland

FIGURES

121

126 128 129 130

CHAPTER 8 Fig. 8.1 Geological map of NW Spitsbergen Fig. 8.2 Liefde Bay Supergroup units Fig. 8.3 Faunal divisions and lithological members of the Wood Bay Formation Fig. 8.4 Geological map of the Raudfjorden/Liefdefjorden area, Northwestern Spitsbergen, showing the distribution of the Siktefjellet and Red Bay groups Fig. 8.5 Schematic section showing the relationships between the units of the Siktefjellet and Red Bay groups Fig. 8.6 Caledonian basement rocks in northwest Spitsbergen Fig. 8.7 Generalized geological map of Biskayerhalvoya, northwest Spitsbergen Fig. 8.8 Principal structural elements (mainly Devonian) of northwest Spitsbergen Fig. 8.9 Map of central west Dickson Land Fig. 8.10 Generalized cross-section across northwest Spitsbergen, from the Albert I Land High to the Andr6e Land Basin Fig. 8.11 Structural profile across the Andr~e Land anticline between Gr~huken and Mushamna Fig. 8.12 Principal bathymetric features off northwest Spitsbergen

133 136 137

139 141 143 145 146 146

147 148 152

CHAPTER 9 Fig. 9.1 Topographic and place name map of Oscar II Land and Prins Karls Forland Fig. 9.2 Diagrammatic outcrop map of central west Spitsbergen Fig. 9.3 Geological map and stratigraphic section of the Ny-.~lesund coalfields Fig. 9.4 Summary of the Paleogene stratigraphic units in Forlandsundet Fig. 9.5 Fence diagram showing the stratigraphic relationships within the St Jonsfjorden Trough Fig. 9.6 Structural cross-section showing the major folds and thrusts in the Mediumfjellet-Lappdalen area Fig. 9.7 Alternative structural profiles across northern Prins Karls Forland to illustrate the different interpretations of the structure Fig. 9.8 Lithostratigraphic formations and geological map of south-central Prins Karls Forland Fig. 9.9 Simplified structural map and cross-sections of the Forlandsundet Graben Fig. 9.10 Schematic diagram of 'flower structure' within a convergent strike-slip fault zone

155 156 157 157 160 171

173 174

196 197

202 203 203

CHAPTER 11 Fig. 11.1 Bathymetric map of the western Barents Sea around southern Svalbard, with principal bathymetric features named 209 Fig. 11.2 Summary of stratigraphic schemes for Bjornoya 210 Fig. 11.3 Geological map of Bj~rnoya 211-2 Fig. 11.4 Summary plot of seismic velocity, porosity and estimated minimal subsidence rate 212 Fig. 11.5 Structure contour map of the base of the Roedvika Formation, with diagrammatic profile 213 Fig. 11.6 Schematic structural map of Bjornoya 220 Fig. 11.7 Geological map and sketch cross-section through basement rocks of southern Bjornoya 221 Fig. 11.8 Structure of the western Barents Sea showing the possible location of the Iapetus suture 223 CHAPTER 12 Fig. 12.1 Outcrops of pre-Vendian rocks (mainly Proterozoic) Fig. 12.2 Precambrian timescale comparing chronostratigraphic and chronometric scales Fig. 12.3 Correlation of pre-Vendian sequences of Ny Friesland and Nordaustlandet Fig. 12.4 Correlation of pre-Vendian sequences of the western terranes Fig. 12.5 Correlation of Precambrian sequences in the western, central and eastern terranes, with some age constraints Fig. 12.6 Map showing the distribution of proto-basement in Svalbard Fig. 12.7 Pressure-temperature plot for the metamorphic complex of Biskayer Peninsula Fig. 12.8 Correlation of East Greenland and Ny Friesland Proterozoic sequences Fig. 12.9 Schematic reconstruction of eastern Laurentia and Baltica for the period 1900-1600 Ma Fig. 12.10 Pre-Vendian aulacogen model showing the distribution of the Greenland, Barents and Baltica cratons Fig. 12.11 Global palinspastic reconstruction for Kanatia timeshowing the locations of rift margins and glacigenic deposits

228 229 230 231

236 237 238 240 240 241

242

176 CHAPTER 13 177

CHAPTER 10 Fig. 10.1 Topographic and place name map from Isfjorden to Sorkapp Fig. 10.2 Generalized outcrop map of central and southwestern Spitsbergen Fig. 10.3 Simplified tectonic map of central and southwestern Spitsbergen Fig. 10.4 Vendian geology of northwest Wedel Jarlsberg Land Fig. 10.5 Stratigraphic schemes for the Precambrian succession of southern Wedel Jarlsberg Land

Fig. 10.6 Comparison of stratigraphic schemes for southwest Spitsbergen Fig. 10.7 Correlation of Pre-Devonian units in southwest Spitsbergen Fig. 10.8 Structural map and representative cross-sections of Nordenski61d Land, illustrating the structure of Carboniferous to Cretaceous units Fig. 10.9 Simplified structural profile across the Midterhuken Peninsula Fig. 10.10 Schematic structural profile of northern Sorkapp Land

180 181 182 190 193

Fig. 13.1 Outcrop map showing the distribution of Vendian outcrops in Svalbard Fig. 13.2 Vendian biostratigraphy and isotopic variations of carbonate rocks Fig. 13.3 Correlation of Vendian successions in Svalbard Fig. 13.4 Secular variation in ~513Cplotted against stratigraphic depth (m) for the Varanger and Sturtian succession of Spitsbergen Fig. 13.5 Interpretation of Vendian environments from the successions of northeastern Spitsbergen Fig. 13.6 Vendian correlation chart for representative successions of Svalbard and adjacent areas of the North Atlantic-Arctic region

245 246 247

249 250

252

FIGURES Fig. 13.7 Correlation of the Vendian successions of East Greenland and northeast Svalbard 253 Fig. 13.8 Schematic palinspastic model for Vendian time showing the inferred positions of the Svalbard terranes and the postulated Iapetus Ocean 253 Fig. 13.9 Global palinspastic reconstruction for Rodinia time showing the distribution of Varanger glacigenic deposits 256

Fig. 16.9 Tectonic evolution and stratigraphic sequences in the Western, Central and Eastern Svalbard Precambrian to Devonian terranes Fig. 16.10 Geological provinces of the eastern part of the Canadian Arctic Archipelago and northern Greenland Fig. 16.11 Summary of strike-slip displacement along the major fault and shear zones of Svalbard to illustrate the possible amounts of sinistral displacement

xi

303 306

307

CHAPTER 14 Fig. 14.1 Cambrian and Ordovician rock units in contemporary nomenclature and classification Fig. 14.2 Map of Svalbard showing the distribution of Cambrian and Ordovician outcrops Fig. 14.3 Cambrian-Ordovician chronostratic time scale divisions with biostratigraphic correlations and estimated chronometric ages Fig. 14.4 Cambrian-Ordovician correlation chart for Svalbard Fig. 14.5 Approximate subsidence rates for the Cambrian-Ordovican sequence in Ny Friesland Fig. 14.6 Simplified geological map and representative profiles of the Motalafjella area (Oscar II Land) Fig. 14.7 Pressure-temperaturetime trajectory for the Motalafjella blueschist-eclogite complex Fig. 14.8 Cambrian-Ordovician tectonic events in Svalbard Fig. 14.9 Schematic correlation of North AtlanticArctic Early Paleozoic sequences Fig. 14.10 Schematic illustration of the CambrianOrdovician palinspastic configuration of Greenland and adjacent terranes according to the strike-slip hypothesis conjectured in this work Fig. 14.11 Ordovician palinspastic map

CHAPTER 17 257 258

259 261 265 267 268 269 269

270 270

CHAPTER 15 Fig. 15.1 Map of Svalbard showing the distribution of Silurian outcrops and areas of tectonism and metamorphism Fig. 15.2 Summary of Silurian time scales Fig. 15.3 Field sketch of the Stubendorff Mountains Fig. 15.4 Cartoon illustrating the elements in tectonic transitions in the Ny Friesland Orogen Fig. 15.5 Schematic profile of the pre-Red Bay Group structure as observed in Biskayerfonna-Holtedahlfonna terrane just south of Liefdefjorden Fig. 15.6 Quantitative petrographical classification of granitic rocks in Svalbard Fig. 15.7 Schematic illustration of terranes surrounding Greenland at approximately the beginning of Silurian time, with the closure of the Iapetus Ocean Fig. 15.8 (a) Late Ordovician to Early Silurian global palinspastic reconstruction, with glacigenic deposits; (b) Mid-Silurian palinspastic reconstruction

273 274 277 277

279 281

287

287

CHAPTER 16 Fig. 16.1 Outcrop map showing the distribution of Devonian deposits in Svalbard and locations of identified thermal events Fig. 16.2 Stratigraphic correlation chart for the (Devonian) Liefde Bay Supergroup of Svalbard Fig. 16.3 Devonian fossil fish reconstructions Fig. 16.4 Devonian fossil fish ranges Fig. 16.5 Distribution of Svalbard Devonian fish genera with time Fig. 16.6 Illustration of a Devonian landscape Fig. 16.7 Schematic diagrams to illustrate successive sedimentation patterns through Devonian time Fig. 16.8 True-scale cross-sections of fold and fault zones in the Devonian rocks of the Gronhorgdalen Belt, Eastern Boundary Belt and an EW cross-section from James I Land to the Balliolbreen Fault

290 292 293 294 295 296 297

302

Fig. 17.1 Map of Svalbard showing the distribution of Carboniferous and Permian rocks 311 Fig. 17.2 Chart illustrating successive classifications of rocks units 312 Fig. 17.3 Lithostratigraphic scheme for Carboniferous and Permian formations of the Bfinsow Land Supergroup 313 Fig. 17.4 Schematic map of Carboniferous and Permian structures 315 Fig. 17.5 Carboniferous and Permian time scale and biostratigraphy 317 Fig. 17.6 Some fossils recorded from Carboniferous and Permian formations of Svalbard 325 Fig. 17.7 Fence diagram illustrating lateral variations and tectonic controls on the Carboniferous stratigraphy 328 Fig. 17.8 Early Carboniferous lithofacies maps 329 Fig. 17.9 (a) Early Bashkirian lithofacies. (b) Moscovian lithofacies maps 331 Fig. 17.10 Gzelian lithofacies map 332 Fig. 17.11 (a) Asselian lithofacies. (b) Early Artinskian lithofacies maps 332 Fig. 17.12 Ufimian lithofacies 333 Fig. 17.13 Principal Carboniferous and Permian tectonic events 335 Fig. 17.14 International correlation of Carboniferous and Permian formations in the Arctic 336 Fig. 17.15 Carboniferous to Permian paleogeologic maps of the Barents Sea region 337-8 CHAPTER 18 Fig. 18.1 Outcrop map showing the distribution of Triassic deposits in Svalbard Fig. 18.2 Correlation chart to show the relationship of published Triassic stratigraphic names in Svalbard Fig. 18.3 Triassic structural framework Fig. 18.4 Triassic lithostratigraphic schemes for Svalbard Fig. 18.5 Sassendalen Group isopach map Fig. 18.6 Kapp Toscana Group isopach map Fig. 18.7 Localities and thickness of the Wilhelmoya Formation Fig. 18.8 Triassic time scales Fig. 18.9 Comparative zonation of Triassic Svalbard successions Fig. 18.10 Stratigraphic correlation chart Fig. 18.11 (a) Early, (b) Mid-(early Ladinian) and (c) Late Triassic sedimentary facies of Spitsbergen, Barentsoya and Edgeoya Fig. 18.12 Triassic sedimentation sequences on Barentsoya and Edgeoya Fig. 18.13 Regional Triassic tectonics Fig. 18.14 Comparison of Arctic shelf sequences in Svalbard and the Queen Elizabeth Islands plotted for the Tournaisian to Maastrichtian interval Fig. 18.15 Triassic palaeogeology of the Barents Sea. (a) Early to Mid-Triassic; (b) Late Triassic

341 342 344 346 347 348 349 351 352 353

357 359 359

360 361

CHAPTER 19 Fig. 19.1 Map of Svalbard showing the distribution of Jurassic and Cretaceous outcrops Fig. 19.2 Hydrocarbon potential and depositional environment of Triassic to Cretaceous rocks of Svalbard

364 365

xii

FIGURES

Fig. 19.3 Historical review of the principal stratigraphic schemes for the Jurassic and Cretaceous of Spitsbergen 366 Fig. 19.4 Jurassic and Cretaceous structural framework Fig. 19.5 Summary of the principal lithostratigraphic units of the Adventdalen and Kapp Toscana groups in Svalbard 367 Fig. 19.6 Jurassic-Cretaceous international time scale 369 Fig. 19.7 Summary of the biozonal schemes for Svalbard and the adjacent Barents Sea 370 Fig. 19.8 Biostratigraphic distribution of belemnite genera in Svalbard 372 Fig. 19.9 Summary of the Jurassic and Cretaceous stratigraphy of Svalbard and the adjacent Barents Sea 373 Fig. 19.10 Summary of the lateral development of the Helvetiafjellet Formation 375 Fig. 19.11 Fence diagram showing lateral variations in the Carolinefjellet Formation 376 Fig. 19.12 Map showing the distribution of JurassicCretaceous igneous rocks 377 Fig. 19.13 Summary of events in the Jurassic and Cretaceous history of Svalbard 381 Fig. 19.14 Lateral variation of the Agardhfjellet and Rurikfjellet formations across Spitsbergen 382 Fig. 19.15 Summary of structural and tectonic events in the Arctic in mid-Jurassic and mid-Cretaceous time 383 Fig. 19.16 Jurassic to Cretaceous palaeogeologic maps of the Barents Sea 384-5

CHAPTER 20 Fig. 20.1 Map of Svalbard showing the distribution of Paleogene deposits and deformation 389 Fig. 20.2 Sequence of classification of Paleogene deposits in the Central Basin 390 Fig. 20.3 Generalized Paleogene structural framework of Spitsbergen 391 Fig. 20.4 Paleogene time scale 392 Fig. 20.5 Successive interpretations of the age of Paleogene strata and events in Svalbard 393 Fig. 20.6 Map showing the geographic-stratigraphic distribution, preservation state and sedimentary facies of palynomorph assemblages 398 Fig. 20.7 Schematic cross-section of the northern part of the West Spitsbergen Orogen 399 Fig. 20.8 (a) Map showing the location of unpublished structural profiles of the West Spitsbergen Orogen 402 (b) Selection of unpublished cross-sections of the West Spitsbergen Orogen by A. Challinor 403-8 Fig. 20.9 Schematic model illustrating the various structural configurations within an area of strike-slip deformation 409 Fig. 20.10 Interpretation of the structural development of Paleogene structures in Nordenski61d Land 411 Fig. 20.11 Historical review of Paleogene tectonic models for Svalbard 411 Fig. 20.12 Paleogene time-scale 412 Fig. 20.13 Sequence of maps showing the motion of Svalbard relative to Greenland (fixed) for latest Cretaceous to Oligocene time 413 Fig. 20.14 Diagrammatic model for the Cenozoic sea-floor spreading, dextral strike-slip and transpression between Svalbard and Greenland 414

Fig. 20.15 Palaeogeologic map of Spitsbergen in Mid-Paleocene time Fig. 20.16 Paleogene palaeogeologic maps of Spitsbergen latest Paleocene to early Mid-Eocene

415 415-6

CHAPTER 21 Fig. 21.1 Neogene and Quaternary volcanics; Quaternary hydrothermal springs, seeps and microseismic zones Fig. 21.2 Neogene and Quaternary time scale Fig. 21.3 Bathymetric features and structures of the Norwegian-Greenland Sea and eastern Arctic Ocean Fig. 21.4 Present-day bathymetric structures in the North Atlantic Fig. 21.5 Map showing depth to basement in Spitsbergen as defined from aeromagnetic data Fig. 21.6 Map of the Bockfjorden area indicating the locations of hydrothermal springs Fig. 21.7 Compositions of Neogene plateau lavas Fig. 21.8 Simplified profiles and Tertiary stratigraphy of the Western Barents Shelf Fig. 21.9 Summary of the Neogene units of the western Barents Shelf margin Fig. 21.10 Interpretation of the Neogene fluvial drainage pattern in the Barents Sea Fig. 21.11 Map of the Barents Sea delineating the main erosion areas from mid-Miocene to Recent Fig. 21.12 Summit-height map of Svalbard Fig. 21.13 Diagrammatic model of the chronology of the deglaciation pattern of the Western Barents Sea Fig. 21.14 Diagrammatic illustrations of patterned ground Fig. 21.15 Late Pleistocene stratigraphy of inner Isfjorden

419 420 420 422 423 424 424 426 427 427 428 429 430 433 434

CHAPTER 22 Fig. 22.1 Map of Svalbard with the distribution of the modern glaciers and ice caps Fig. 22.2 (a) Map of estimated precipitation over Svalbard; (b) Map of estimated equilibrium line altitude over Svalbard Fig. 22.3 Landsat satellite image of Nordaustlandet with the interpretation of ice-cap drainage basins inset Fig. 22.4 Airborne radio-echo sounding data from Austfonna, Nordaustlandet Fig. 22.5 Ice surface and bedrock profiles from radio-echo sounding of Nordaustlandet Fig. 22.6 Fast-flowing glaciers on Vestfonna Fig. 22.7 Photographs of a surge of Bakaninbreen, Spitsbergen Fig. 22.8 The terminus of a tidewater glacier Fig. 22.9 Photographs of constrasting iceberg morphology: (a) tabular, (b) irregular Fig. 22.10 Temperature records from 1912 Fig. 22.11 Mass balance records for three Spitsbergen glaciers Fig. 22.12 Energy balance model predictions of glacier response to future global warming Fig. 22.13 Oxygen isotope ratios from Lomonosovfonna since about AD 1200

437

438 439 440 441 441 442 443 444 444 445 445 445

APPENDIX Fig. 23.1 Plot of major wells in Svalbard Fig. 23.2 Mesozoic petroleum source-rocks of the Arctic

451 453

Tables Table Table Table Table Table

1.1 Geographical nomenclature for Svalbard archipelago 5 1.2 Arctic summers and winters in Svalbard 8 3.1 Precambrian chronometric scale 28 15.1 Eastern and western outcrops of Ny Friesland 276 16.1 Divisions of the Devonian 289

Table 17.1 Divisions of the Kapp Starostin Formation Table 17.2 Carboniferous and Permian sedimentation rates Table 19.1 Average of chemical analysis made by Tyrrell & Sandford (1933) Table 23.1 Deep well data for Svalbard

327 334 378 452

Photographs Interior of south central Spitsbergen from the air Cover Ny-Alesund and Tre Kroner ii Bay ice in Thiisbukta and Scheteligfjellet seen from Ny-A.lesund ii Comfortlessbreen and Aavartsmarkbreen from near the shore 1 Crevassed Monacobreen snout seen from the east 1 Small bergs in inner Kongsfjorden with Broggerhalvoya beyond 2 Late summer in mid Kongsfjorden with Kapp Mitra and the motor boat Salterella 2 Snow camp in southwest Lomonosovfonna looking down Wilsonbreen 45 Snow-capped mountains of Ny Friesland from northern Lomonosovfonna 45 Snow scooter in the middle reaches of Tryggvebreen, Ny Friesland 46

Tracked amphibious vehicle hauling sledges at Draken, Ny Friesland Camp on Nordenski61dkysten, a strandflat on the west coast of Spitsbergen Camp by Siktefjellet on raised beach north of Liefderfjorden The motor boat Arctoceras equipped for living aboard and working ashore The motor boat Salterella helped on her way through pack ice A safe anchorage for easy access ashore below Alkhornet Routine boat passage through Smeerenburgfjorden en route to the north The motor boat Salterella in north Liefdefjorden anchored off Erikbeen Access up Hannabreen from Liefdefjorden with signs of the end of summer

46 225 225 226 226 447 447 448 448

Preface 'I think that we shall have to get accustomed to the idea that we must not look upon science as a "body of knowledge", but rather as a system of hypotheses; that is to say, as a system of guesses or anticipations which in principle cannot be justified, but with which we work as long as they stand up to tests, and of which we are never justified in saying that we know they are "true" or "more or less certain" or even "probable".' Karl A. Popper (From a paper that Popper read in 1934 when his Logik den Forschung was in proof. It was published in English in the new appendices of his Logic of Scientific Discovery 1959, p. 317).

This work attempts to present the geology of Svalbard in some detail, arranged systematically as a definitive study and so reflecting the present conjuncture of research. It may thus meet the needs of specialists with information on related fields or of any geoscientist wanting an indication of what is known about this key region. Spitsbergen (peaked mountains), the name earlier referred to the whole archipelago. It is now replaced by the name Svalbard (cold coasts), within which Spitsbergen is the principal landmass. Spitsbergen alone is about the size of Switzerland and the whole archipelago a little less than the area of Scotland. Geologically it has the wealth in variety and complexity in stratigraphy and structure no less than these classic areas. Moreover with an international history and present treaty status many nations have participated in research so the geological literature currently comprising far more than 3000 publications is widely scattered and rapidly increasing. There are indeed excellent published geological outlines, but no comprehensive work. Part 1 of this work is introductory, setting the stage. Chapter 3 in particular presents the principal geological conventions used throughout and outlines the main geological features and tectonic hypotheses. Part 2 divides Svalbard into eight somewhat arbitrary regions/sectors which are described with minimal interpretation. The rock successions are described briefly from the top down as observed, and the structures are outlined and to some extent illustrated. Part 3 interprets historical events and environments from oldest to youngest in successive time-slices. Part 4 comprises an appendix on economic geology and four alphabetical lists (place names, stratigraphic names, references and general index). Small type has been used throughout the text for detail that may be skipped when only the main argument is of interest. My interest in the project stems from about 50 years of research in many aspects of Svalbard geology with some 50 colleagues and collaborators listed below. However this book purports to be an objective study of contributions from international sources. Where there are differences of opinion alternative views are presented. Obviously, however, no single person could comprehend the whole literature nor avoid some personal bias when making a coherent synthesis that has been thought through. These objectives would take more than a life-time to fulfil. This work is presented as a contemporary statement in the spirit of the quotation at the head of this preface. By venturing conjectures and exposing them freely in graphic form as well as in the text it is intended that they shall be subject to critical assessment. Lack of appropriate evidence does not vitiate an hypothesis nor can abundant supporting evidence establish it. Only contradictory evidence provides effective criticism. This work presents a challenge and a platform for further research and will be superseded in the normal course of science. The philosophy behind this study is that all geological data may be integrated in space and time, that is stratigraphy in the broad sense. This regional synthesis is offered as a contribution to Earth history. It is a two way interaction. Understanding of process enables and demands the interpretation of historical data and the attempt to understand history leads to further modifications in the theory of the Earth. For example: the attempt to make sense of the field data led to early hypotheses of continental drift; of cooling and heating of the mantle with regional subsidence and uplift; of compression leading to lateral escape, transpression and transtension; of large scale paleo-strike-slip of former provinces and allochthonous terranes; and of global Vendian glaciation.

This is a personal synthesis at the conclusion of work epitomizing a journey that began for me in Spitsbergen on graduation in 1938. I have been privileged as a student and teaching officer in a great University and as a member and Fellow of an ancient Cambridge College. These positions require specified duties in teaching and administration, but with freedom to pursue investigations whenever and wherever they may lead, provided the necessary resources can be found. I came into a culture where the older generation worked out their own research as individuals with little or no organized cooperation. After two abortive research lines I decided in 1948 both to attempt to tie up some unfinished work in Spitsbergen and at the same time to try out a pattern of cooperative research with our students. All I have learned about research was gained through such interaction and that is why I dedicate this work to those colleagues. Some, hardly junior, have long achieved distinction. About 400 persons have in diverse ways contributed to our joint enterprises. I draw attention to the early decades when fieldwork involved long boat journeys to Spitsbergen and then transport by small open boats, manhauled sledges and always much pack-carrying to the study area. Equipment was primitive and conditions often harsh. We thought ourselves fortunate indeed to share the experience of our predecessors in Svalbard exploration. I mention only two colleagues. Colin B. Wilson worked with me in N y Friesland contributing greatly to the work in Chapter 7. His contribution, first in our systematic survey of Ny Friesland and later on his private solo excursions by small boat with outboard, carrying sledges and supplies from Longyearbyen round the northwest to N y Friesland where he recorded exemplary observations across enormous distances. His motivation was the shear joy of discovery and only with difficulty was he persuaded to prepare work for publication. His death in 1959, not in Spitsbergen, but by an accident in Cambridge, deprived us of a remarkable investigator. C. John B. Kirton a brilliant first year student was killed in 1958 by a flying stone while holding a fossil at a new locality on a mountain later named after him. A service was held in 1959 at his remote grave and memorial cairns were built nearby and by the shoreside base. He represents the best in our university tradition. Our research group was never an official university project and we paid our way as best we could in the early days, contributing personally. The need for independence led to the formation of Cambridge Spitsbergen Expeditions, (later Cambridge Svalbard Exploration). This then led to the formation of the Cambridge Arctic Shelf Programme to give more security of employment and to spread our interests so as not to compete for limited funds in Britain or Norway. Finally I acknowledge one colleague, my wife Elisabeth, who in the early years looked after our family taking domestic responsibility single handed. In the middle years she assisted in Svalbard on 13 field seasons and has latterly given invaluable support to my writing of this work for which I alone must bear full responsibility. W. B. Harland July 1997

Department of Earth Sciences University of Cambridge Downing Street Cambridge CB2 3EQ

Acknowledgements Two kinds of acknowledgement relate to the research and to this publication. First paying tribute to those to whom the book is dedicated the research has benefited from the participation of many colleagues during 45 field seasons as well as in Cambridge. They contributed greatly to my education and determination to write this book. It may be of interest to other Svalbard geologists to note who have published from this experience. In list A those names with asterisks worked on Svalbard material for their research degrees, others participated, some over long periods. It would, however, be wrong to think only of the geologists whose reward was in their work. We depended throughout on logistic support. Of the hundred or more who supported the work in this way list C names those who took responsibility for more than one season, for example captaining boats. More than a hundred geology undergraduates joined as assistants and many have gone on to distinguish themselves. They often asked the most penetrating questions, made unlikely observations and were rewarding companions. Whereas the above thanks are for my own personal indebtedness to those who have shared in the work I gladly acknowledge the immense debt due to the larger scientific community whose published work is the basis of this book as may be noted from the list of publications cited. At the same time I should declare that by no means have the extensive files of CSE and CASP unpublished work been abstracted here. I remembered only what seemed relevant to the arguments. Nevertheless to have traversed the ground myself enabled the literature to be better appreciated. For help with the many aspects of the book it is both a pleasure and a duty to acknowledge the following: D. Manasrah's patient committal to disc of my scribble and good tempered acceptance of the need for innumerable revisions. L. M. Anderson helped manage the later stages of the book, executing most of the figures, listing place names and checking the whole for submission on disc. Both were employed by CASP on this work, (Cambridge Arctic Shelf Programme, West Building, Gravel Hill, Huntingdon Road, Cambridge C B 3 0 D J ) . Whereas I drafted most of the text and sketched most of the figures others contributed of their expertise as indicated in

the chapter headings. The late Dr A. Challinor gave permission to include the serial cross sections of the West Spitsbergen Orogen from his dissertation and later CSE reports (Section 20.6); D. I. M. Macdonald, Chief Geologist of CASP, supported this work throughout and seconded CASP staff at different times to this project. I. Geddes helped with the proofs. The place name list was compiled by Mr L.M. Anderson The lexicon of stratigraphic names begun in the fifties was abbreviated and checked recently in co-operation with W. K. Dallmann (Norsk Polarinstitutt Geologist and Chairman of the SKS) The more comprehensive bibliography (the basis of the reference list here) has a long history beginning with the earliest research. Managed for many years as a card index by K.N. Herod it was in due course computerised initially by R. A. Scott (CASP) and subsequently updated at regular intervals with the continuing help of D. Manasrah (CASP), and E. L. Lesk, Information Officer in CASP, who scanned new literature for me through this work. Publications were listed as met in the work and not sought out for a comprehensive bibliography. Unless otherwise stated in the captions, the figures were devised and sketched by me and then executed on disc by those who have initialled the diagrams, mainly L. M. Anderson, C. F. Stephens, S. R. A. Kelly, D. Manasrah and P. A. Doubleday. M. J. Hambrey, P. W. Webb and N. I. Cox provided most of the supplementary photographs that appear as the frontispiece and on the cover page for each of the four parts of the book. At a late stage in preparation of the manuscript I owe much to help from those who made useful improvements, especially to M. J. Wells (University College London) for correcting my Norwegian (and English), to F. Cooley (CASP) for checking most of the Russian transliterations in the reference list. The remaining mistakes would not be due to any failure on their parts. Named referees contributed significantly: in addition to A. M. Spencer's contribution in the Appendix, P. F. Friend, A. J. Martin and J. R. Parker suggested where improvements could be made. Finally the work has benefited from the professionalism of the staff of the Geological Society Publishing House in Bath, particularly the Staff Editor Angharad Hills.

(A) Geologists accompanying Cambridge field parties (and/or) who have had Svalbard research published * K. C. Allen L. M. Anderson K. A. Auckland * D. J. Batten * M. B. Bayly * D. E. T. Bidgood G. S. Boulton S. H. Buchan * H. J. Campbell * A. Challinor * C. Croxton * J. L. Cutbill * M. Dettmann J. A. D. Dickson P. W. Ditchfield E. K. Dowdeswell J. A. Dowdeswell * M. Dowling P. Doyle I. J. Fairchild * C. L. Forbes * R. A. Fortey * P. F. Friend

* M. D. Fuller * R. A. Gayer I. Geddes * D. G. Gee E . R . Gee * D. J. Gobbet A. Hallam M . J . Hambrey M. Head A . P . Heafford W . G . Henderson K . N . Herod * D. W. Holliday * W. T. Horsfield * K. Howells N . F . Hughes * P. F. Hutchins * L. K a n a t S . R . A . Kelly A . H . Knoll J. Laing U. Lehmann B . E . Lock

J. Lowry S . R . Lu D . I . M . Macdonald * A. J. M c C a n n * J. R. H. McWhae * G. M. M a n b y * A. M a n n * D. Masson-Smith * P. I. M a t o n * M. Moody-Stuart * A. P. Morris J . E . Odell * J. R. Parker C . A . G . Pickton * G. Playford * D. J. W. Piper S . P . Price M. Quest P . F . Rawson A . B . Reynolds W. Schwarzacher R . A . Scott * D. G. Smith

. . .

xvm M. P. Smith I. Snape 9 H. Spall C. F. Stephens K. Swett

ACKNOWLEDGEMENTS F. Thiedig R . S . W . Thornley C. Townsend G. Vallance R . H . Wallis

* P. Waddams * C. B. Wilson T . S . Winsnes N . J . R . Wright R . T . Wu

* Svalbard research students at one time

(B) Some of those who contributed to the field work and later in other ways M. J. Allderidge T. R. Astin P. B. H. Bailey M. H. P. Bott D. D. Clark-Lowes A. P. R. Cooper L. E. Craig T. A. Davies

J . G . Elbo N. Golenko G . E . Groom B. Harte E . M . Himsworth C . A . Jourdan R. Mason D . P . McKenzie

B. Moore M.J. O'Hara P . C . Parks C . V . Reeves O . P . Singleton J . C . Tippen F . J . Vine P . T . Warren

(C) Logistic leaders (e.g. boat captains) for more than one season R. A. Browne M. F. Chantrey N. I. Cox

W . D . H . Fairbairn R N J. H Gammage A . H . Neilson

A. C. Smith M. Tuson

Participants W. B. HARLAND

Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK L. M. ANDERSON

CASP, West Building, Gravel Hill, Huntingdon Road, Cambridge CB3 0DJ, UK D. MANASRAH

CASP, West Building, Gravel Hill, Huntingdon Road, Cambridge CB3 0DJ, UK N. J. BUTTERFIELD

Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK A. CHALLINOR (DECEASED)

Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK P. A. DOUBLEDAY

CASP. Present address: Amerada Hess Ltd, 33 Grosvenor Place, London SW1 X7HY, UK E. K. DOWDESWELL

Centre for Glaciology, Institute of Geography and Earth Sciences, University of Wales, Aberystwyth, Cardigan SY23 3DB, UK J. A. DOWDESWELL

Centre for Glaciology, Institute of Geography and Earth Sciences, University of Wales, Aberystwyth, Cardigan SY23 3DB, UK I. GEDDES

CASP. Present address." 1 School Close, Keevil, Trowbridge BA14 6SB, UK S. R. A. KELLY

Consultant with CASP, 10 Belvoir Road, Cambridge CB4 1JJ, UK E. L. LESK

CASP, West Building, Gravel Hill, Huntingdon Road, Cambridge CB3 0DJ, UK A. M. SPENCER

Statoil, Forushagen, 4035 Stavanger, Norway C. F. STEPHENS

CASP. Present address." Amoco (UK), Amoco House, West Gate, London W5 1XL, UK

Conventions Geological conventions employed throughout the work are treated in Chapter 3. These include the international time scale, principles for lithostratigraphic nomenclatures, the uses of some technical terms and the descriptive names for Svalbard structures. Place names are explained in Chapter 1 and listed in Part 4.

Acronyms in common use

Authority It is intended that any positive statement be supported by a reference at the end of the paragraph or subsection. If none it may be assumed either that the statement is common knowledge or that it is the original contribution (opinion) of this work. The names of up to three authors may be cited in the text and 'et al.' generally refers to four or more.

CSE: Cambridge Spitsbergen Expeditions, Cambridge Svalbard Exploration. CASP: Cambridge Arctic Shelf Programme. GSSP: Global stratotype section and point. IKU: Continental Shelf Institute, Trondheim. lUGS: International Union of Geological Sciences. NP: Norsk Polarinstitutt. SKS: Stratigrafisk Komit6 for Svalbard.

Use of contemporary nomenclature and compass orientation

Contractions in figures where space is critical

Transfiteration

-fjt (-fjellet); -fdn; fin (-fjorden); -fja (-fjella); -bn (-breen)

The Norwegian alphabet places symbols o and 6 ~t a~ at the end whereas they are placed here as though unmodified in the English language alphabetical order. For Chinese: Pinyin For Cyrillic: The system used was jointly recommended by the Permanent Committee on Geographical Names (PCGN) for British Official use and the United States Board on Geographical Names (USBGN), as revised in 1970 and 1972. It is used in the Times Atlas of the World, the Scott Polar Research Institute and the Geographical Names Division of the US Army Topographic Command, which has published perhaps the most comprehensive gazeteer of the FSU. The ISO system has advantages but requires the addition to normal type of accurate diacritical symbols unfamiliar in the west.

Time conventions Three-letter abbreviation of age names follow Harland et al. (1990), see Chapter 3.2. Formal use of subscript numbers 1, 2 & 3 = Early, Mid- and Late, which are not abbreviated. Ma is the usual symbol for the age in millions of years as also ka for thousands of years before present (BP).

In recording earlier work, unless original wording is quoted (in quotes), the present usage (for example of place and stratigraphic names) is generally substituted. Original names may be added in parentheses. Compass directions for earlier geological ages are expressed in the present orientation without implication as to what was the ancient orientation.

Rock units U, M & L upper, middle and lower for rock units only. 'Thickness' in metres is not added to numbers i.e. 100m to indicate 100m thick unless otherwise specified.

Lithologies Lst, dst, sst, slst, sh, cgl (conglomerate), qi (quartzite); aren. (arenaceous); dol (dolomite-except. dst); unto. (unconformity, unconformable).

Use of stratigraphic nomenclature (as explained in Section 3) The problem of divergent stratigraphic nomenclature and classification has been met by a discussion arriving at a conclusion generally early in each historical chapter. That discussion, often seemingly of miniscule interest, may then be confined to that particular section. The conclusions may be applied in the rest of the work both in earlier or later parts. Therefore, the reader who finds a different scheme employed and is possibly irritated thereby, should find the reasoning behind such a choice in a section in each of the historical chapters. The Stratigraphic Glossary may help.

PART 1 Introduction Chapter 1 Chapter 2 Chapter 3

Svalbard, 3 Outline history of geological research, 16 Svalbard's geological frame, 23

Mid-season view of the glaciers Comfortlessbreen (on the left) and Aavartsmarkbreen (beyond). The rocks are Early Vendian with Varanger tillites. Stratigraphic sections are generally worked along the glacier margins either by porterage from the shore (in this case Egelskbukta) or by sledge from the interior. Photo M. J. Hambrey (SP. 455).

Late season view from the east over the terminal crevassed glacier Monacobreen. In this case access up the glacier is almost impossible because the lower reaches are deeply crevassed and the glacier terminates in ice-cliffs in inner Liefdefjorden. The glacier beyond offers an easy route westward. Photo P. W. Webb, CSE 1989.

View from Ossian Sarsfjellet at the eastern end of Kongsfjorden towards the mountains of Broggerhalvoya which are reflected in the fjord. The intervening fjord carries a scatter of small bergs which have calved from the glacier cliffs of Kronebreen and Kongsbreen respectively to north and south of the photographer. The concentration of ice depends on wind and tide and is navigable with care in a slow moving boat. The small bergs melt rapidly in the summer. Photo M. J. Hambrey (SP96.122) 1996.

The CSE motorboat Salterella in mid-Kongsfjorden seen when looking out to sea with the landmark K a p p Mitra to the right where the rocks are Caledonian metamorphosed basement of pre-Vendian rocks. This is a late summer scene in an outer fjord. Snow on land and floating ice have gone. Weather generally deteriorates at this time so this is unusually a calm evening scene. Eider duck are flying and on the water. Photo P. W. Webb, CSE 1989.

Chapter 1 Svalbard W. B R I A N 1.1 1.1.1 1.1.2 1.1.3 1.2 1.3 1.3.1 1.3.2 1.3.3 1.3.4 1.3.5 1.3.6 1.4 1.5 1.6 1.6.1 1.6.2

Geographical names, 3 Principal islands and fjords, 3 The lands, 7 Norwegian place names, 7 Topography and bathymetry, 7 The physical environment, 8 Latitude and daylight, 8 Marine influences, 8 Weather, 8 Sea ice, 8 Snow and ice cover, 10 Frozen ground, 10 The biota, 10 Political history, 11 The Spitsbergen Treaty, 11 Administrative consequences of the Treaty, 11 Strategic consequences of the Treaty, 11

An introduction to Svalbard is as necessary for a geoscientist as for any other student of the archipelago. The section on geographical nomenclature is illustrated by maps which are designed to locate many of the commonly used names. These and others are listed at the end of the volume where additional names used later are referred to. The regional context of Svalbard is shown in Fig. 1.1. The present-day physical environment is mentioned, but treated more fully in Chapters 21 and 22.

HARLAND 1.6.3 1.6.4 1.7 1.7.1 1.7.2 1.7.3 1.7.4 1.7.5 1.7.6 1.7.7 1.8 1.8.1 1.8.2 1.8.3 1.8.4 1.8.5

The section on the present-day Svalbard biota is not by a specialist for specialists, but is intended to list those organisms commonly encountered in the field and of interest to most workers. The political and treaty considerations are interwoven and have sometimes left the Norwegian administration in an ambivalent position. Happily however the resources forthcoming from the petroleum industry to the nation has enabled the administration to fulfil its responsibility admirably and latterly without the pressures from the Cold War. Svalbard for its size has a small population, less than 4000 concentrated in relatively few settlements, but numbers are augmented by summer arrivals of construction/maintenance staff, tourists, students and scientists, while the residents often take their summer holidays on the mainland. The environmental threat from this expanding seasonal population presents one of the most serious challenges, while at the same time tourism is replacing coal mining as the principal economic resource. Provision of shipping facilities supplemented by air travel is transforming the economy, which however still requires substantial subsidy. The international community has generated more than 3500 geoscientific publications of which about 2500 are listed in the references. The official publication series are outlined at the end of this chapter. This work attempts to encompass the present geological nature of Svalbard and to interpret its history. It is mainly concerned with evidence from above sea level and this may be justified in part by some more recent interpretations of the Spitsbergen Treaty which claims for Svalbard not more than about 4 nautical miles offshore. The immense area of the submarine Barents Sea floor, the exploration of which resulted in enormous resources, is not treated here except for occasional mention. That would require another work on this scale and by another author. A recent convenient survey of what is known was provided by A. N. Nystad (1996) on the geology and petroleum resources of the Barents Sea; but as with so much knowledge obtained industrially, references to sources are not given. However this volume is mainly concerned with published information together with original thinking.

1.1

Fig. 1.1. Regional geographical setting of Svalbard, with typical maximum and minimum limits of pack ice. Simplified and redrawn from Harland (in press) Norway. Svalbard in Encyclopedia of Worm Regional Geology, fig. 1.

Economic/political consequences of the Treaty, 11 Environmental consequences of the Treaty, 12 Settlements, 13 Longyearbyen, 13 Sveagruva, 13 Ny-Alesund, 13 Barentsburg, 13 Pyramiden, 13 Other settlements, 13 Manned Norwegian radio and meteorological stations, 13 Official publications, I3 Bathymetric charts, 14 Topographic maps, 14 Geological maps, 15 Thematic maps, 15 Scientific serials of the Norsk Polarinstitutt, 15

1.1.1

Geographical names Principal islands and fjords

The archipelago, whose geology is the subject of this work, lies on the northwest corner of the Barents Shelf 650 km north of Norway.

4

CHAPTER 1

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SVALBARD The name Spitsbergen was given by the Dutch captain, Barents, who is generally credited with the modern discovery of the islands in 1596 and after whom the Barents Sea is named. Barents did not know that the name Svalbard (cool coast) was mentioned in the Islandske Annaler in A D 1194 and in the Landndmabbk (approximately AD 1230) from Viking exploration. It was supposed that this archipelago was the northern land referred to, although it was only much later that a clear distinction was made between Spitsbergen and Greenland. Also Russian hunters are claimed to have built huts in the fifteenth century and possibly earlier (Baron 1986). The name Spitsbergen refers to the pointed mountain peaks that the main island exhibits on approach from the sea. It had been used for the whole archipelago or for the main part of it excluding the outlying islands. Spitsbergen was the name for the whole archipelago in the Treaty of S6vres in 1920, and in the Spitsbergen Treaty, which came into effect in 1925. The main island had been known as West Spitsbergen. The name Svalbard was formally introduced by A. K. Orvin in Place Names of Svalbard (1942), by the Norsk Polarinstitutt (the Norwegian Polar Institute in Oslo) in the first systematic and descriptive gazeteer. In Place Names of Svalbard Spitsbergen was redefined to comprise the main group of islands, excluding the outlying islands Storoya, Kong Karls Land, Hopen (Hope island) and Bjornoya (Bear Island). The nomenclature was revised again (Hjelle 1970) so that Spitsbergen now refers only to the main island and excludes Nordaustlandet (North East Land), Barentsoya, Edgeoya, and Prins Karls Forland (Fig. 1.2). Place Names was supplemented in 1958. Until the Spitsbergen Treaty, which awarded the administration of the archipelago to Norway, the islands had been, in the words of Sir Martin Conway (1906), a 'no man's land'. There was no sovereignty and the principal competing nations first for whaling (1600 until the whale population was decimated around 1750) were Dutch and British; then for mineral rights American, British, Norwegian, Russian and Swedish. Scientific exploration went hand in hand with penetration beyond the coastline in a series of expeditions from Britain, (e.g. Scoresby 1820, Parry 1827), Norway (Keilhau 1831), Sweden (Torell 1859, Nordenski61d 1863, Nathorst 1910), Monaco (1899) with increasingly international participation. Consequently most prominent features were named in various languages. Whereas systematization and Norwegianization of older place names led to a single standard for scientific and cartographic description, for geological use once a rock unit name has been established, its original name remains unchanged except for change of rank etc. For example, in the literature before 1940 a common name in English for a fjord in the northwest was Red Bay. This was Norwegianized to Raudfjorden in i940 but the name Red Bay Conglomerate etc. still stands even if changed to Red Bay Formation or Group. Place names of Svalbard (Anon 1942) is a mine of historical information as well as a systematic Norwegianization of place names, and some principal geographical suffixes from that work are listed below. In addition to names for physical features (islands, mountains, glaciers, fjords etc.) the larger areas of Svalbard are divided into lands which are convenient for descriptive purposes (Fig. 1.3). Place names used in this work are listed at the end of the volume with figure numbers of some maps where they may be found. It is generally a scientific convention (as in this work) to follow the official geographical nomenclature of the Norsk Polarinstitutt (Table 1.1). Geological nomenclature will, as far as possible, follow generally recognized international principles taking into account recommendations of the Stratigraphic Committee for Svalbard (SKS). Even when discussing early work present nomenclature is generally employed here. Until about the middle of the nineteenth century there was little exploratory interest in the land. Indeed the prime concern was exploiting marine wealth. Fjords, anchorages and coastal hazards were the main concern. Thus the names of the principal accessible fjords were of great use in navigation. The Place Names of Svalbard recounts their early history. Therefore Fig. 1.2 also plots the present nomenclature of islands and coastal waterways.

5

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Table 1.1. Geographicalnomenclativefor Svalbard

Present nomenclature

1942-1960

pre- 1942*

Svalbard

Svalbard

Spitsbergen or Spitsbergen and Bjornoya

Spitsbergen and associated islands

Vestspitsbergen

Treaty 1925 West Spitsbergen?

Nordaustlandet

Nordaustlandet

North East Land

Barentsoya

Barentsoya

Barents Island*t

Edgeoya

Edgeoya

Edge Island*:~

Prins Karls Forland

Prins Karls Forland

Prins Charles Forland~w

Storoya

Storoya

Great Island

Kong Karls Land

Kong Karls Land King Charles Landw

Hopen

Hopen

Hope Island

Bjornoya

Bjornoya

Bear Island

* Originally in many languages. t Willem Barents, leader of Dutch expeditions 1594 to 1597. $ After Thomas Edge, early seventeenth century English whaler. wSeen by Barents and later named for Charles, Prince of Wales and later King of Britain and Ireland. [[Although discovered at least as early as 1617 by T. Edge this name was proposed by Petermann after Karl I (1823-91) King of Wtirttemberg.

Fig. 1.4. Map showing the principal topographic features of Svalbard, approximate locations of mountains are indicated by triangles with elevation in metres. Ice-cover in white is demarcated by dotted lines.

SVALBARD

1.1.2

7

The lands

The smaller islands need no further classification, but Spitsbergen and Nordaustlandet are now divided into lands for general descriptive purposes. These are not political units and have no precisely defined boundaries. Some names are as old as the island names in use and in many forms before the separate islands were distinguished as, for example, Ny Friesland. Other areas have been designated to complete the modern mosaic with the names of the Norwegian royalty, as for example Olav V Land which was introduced after the publication of Place Names o f Svalbard as in Fig. 1.3. The boundaries shown on Fig. 1.3 are diagrammatic and have no authority. In this work Ny Friesland will continue to describe the area which includes much of Olav V Land. Indeed for geological description Svalbard is classified in this work into sectors that are the descriptive Chapters 4 to 11 and also into terranes. These divisions are peculiar to this work. They are explained in Chapter 3.

1.1.3

Norwegian place names

Since 1942, with the publication of Place Names o f Svalbard, all official names have been Norwegianized: descriptive names being translated; proper names being preserved and usually each is combined with a geographical term. The last one or two letters of the term indicate the definite article, which in Norwegian syntax may be omitted, but in international and especially geological application the name should be indivisible. The plural form may modify the suffix. The common terms used as suffixes in place names are listed here. Mountains and hills, etc.: berget, fjellet, haugen, kammen, kollen, nuten, piggen, ryggen, tinden, toppen. Valleys, passes: dalen, passet. Plains etc.: sletta, vidda, oyra, flya, steinen (stone). Glacial: corrie, glacier, icefield: botnen, breen, fonna, jokulen, morene. Rivers and streams: elva bekken. Lakes, tarns: vatnet, laguna, tjorna, tjernet. Coastal inlets: hamna, pollen, bukta, vftgen. Coastal promontories: halvoya, huken, neset, odden, pynten, tangen, kapp. Shore: stranda. Water: sjoen (sea or lake), fjorden, sundet, flatet (sea bottom). Submarine features: banken, renna, flaket. Shoal, reef and skerry: grunnen, revet, skja~ret. Islet, island: holmen, oya. Settlement, mine, hut, cabin: byen, gruva, hytta, varden (landmark or cairn). Similarly the Norwegian geographical terms for north, northern etc. may constitute the first element in the place name thus: aust, austre; nord, nordre; sor, sore; vest, vestre. There remain a number of (descriptive) names which stand on their own e.g. Lykta, Eplet, Krokodillen. Happily these are often brief. The geological use of place names is discussed in Chapter 3. In maps and diagrams where space may be critical, contractions and abbreviations of the suffix are useful as -fjt for -fjellet, -fja for fjella, -fdn- for fjorden, -bn for -breen.

1.2

Topography and bathymetry

The northwestern margin of the European continental lithosphere comprises the Barents Shelf (Fig. 1.5). Extending northwards from Norway and northwestern Russia, the shelf is covered by the Barents sea except at the northwestern margin where the Svalbard archipelago, and further east Franz Josef Land emerge. The northern margin of the shelf is marked by the continental slope down to the Polar Ocean Basin. The western margin of the shelf similarly terminates along the oceanic Norwegian Greenland Sea.

Fig. 1.5 Bathymetry of the western Barents Shelf. Isobaths (in metres). (simplified from the map of Western Barents Sea Bathymetry, 1: 1 500 000, Norsk Polarinstitutt, Oslo, 1989).

Within the Barents Sea water depths rarely exceed 400 m. In the ocean basins they plunge rapidly from 500 m to 2000 m. On the shelf the bathymetry reflects Neogene and Quaternary history with a subdued drainage pattern. The topography of Svalbard, while reflecting the detailed geological structure which determines many contrasting land forms, shows certain general features. Sea-level changes have eroded and then exposed large tracts of nearly flat land or raised beach. A typical coastline consists of low cliffs seldom exceeding 10m and a coastal plain (strandflat) of variable width behind which steep mountains rise.

8

CHAPTER 1

The mountain peaks all fall within a general summit envelope representing an uplifted and warped peneplane almost regardless of the attitude of the strata, typically about 1000m. Land sculpture is a continuation of glacial erosion resulting in steep cliffs, valleys and glaciers. Other mountain contours typically result from a cold-desert environment with steep scree slopes and cliffs, where the rocks are resistant, giving little opportunity for vegetation to become established. Soft rocks give a more subdued landscape. The variety of land forms is typical of the Arctic as illustrated by Thor6n (1969)

1.3 1.3.1

The physical environment Latitude and daylight

The main islands lie between 76 ~ and 81~ Many distinctive features of this Arctic environment derive from the angle of incidence of solar radiation (Table 1.2; Kosak 1967 p. 99).

1.3.2

Marine influences

Svalbard is a relatively small archipelago and the climate is influenced by two sources of surface ocean water: (i) the West Spitsbergen Current, is the northern-most remnant of the Gulf Stream moving relatively warm water northwards along the west coast; (ii) the East Spitsbergen Current brings cold water and packice southwestwards east of Spitsbergen and the eastern islands. These currents meet off Sorkapp and the cold water is deflected and continues northwards between the warmer current and the coast, often carrying pack-ice with it, and causing fog (Fig. 16). On the western approaches the upper Atlantic layer of approximately 200-900 m in depth has a fairly uniform temperature of about 3~ whereas the bottom layer may be about - 1.0~ The tides range between about 2 m for spring and 1 m for neap except where restricted by land.

1.3.3

Fig. 1.6. Prevailign surface currents of the Barents Sea and North Atlantic areas, abstarcted from V. Hisdal (1985, fig. 12, p. 21) Geography of Svalbard.

is about 300-400mm (with a maximum of about 1000mm), most of which falls as fine snow or rain in summer and autumn. In summer the low humidity, cold land and warm air interact, often causing dense fog and low cloud over the glaciers and ice filled waters. In winter it is usually clear. The summer air temperature at sea level averages about 4-5~ and in winter about - 1 2 C ~ and commonly down to - 2 0 ~ in the west. Temperatures are lower towards the north and east. Summer temperature may rise to 10~ the extreme range may be - 5 0 ~ to +22 ~ There is usually some wind, which may be strong locally, especially in long fjords with direct access from inland ice. Mirages, haze, ice blink and white-out are all common.

Weather

Annual precipitation is low. In the east it is almost all snow and may be as low as 10 mm, per year. On the west coast the average

Table 1.2. Arctic summers and winters in Svalbard Latitude

80~ 79~ 70~ 66.5~

Number of days of continuous Daylight

Darkness

137 107 70 23

123 94 55 0

1.3.4

Sea ice

There is an inexhaustible supply of pack ice (often some years old) drifting from the polar basin with the East Spitsbergen Current. It depends for its subsequent distribution mainly on the marine currents but often and unpredictably on winds. It melts slowly in the warmer waters. The old, thicker, harder ice is a more serious factor in shipping especially when it drifts round the south of Spitsbergen and then northward along the west coast. On the other hand the annual freezing and thawing in the fjords provides a bay ice (never exceeding a metre in thickness) that melts rapidly, becoming rotten in early summer. A third floating hazard are the icebergs that come from calving glaciers. Larger bergs occur in many fjords and beyond,

Fig. 1.7. Principal ice cover and valleys of Svalbard. The ice-covered areas shown on the map are extremely generalized. Glaciers etc. are numbered black circles and valleys are numbered rectangles, each are listed in alphabetical order. Glaciers: (1) Aavatsmarkbreen; (2) Aust Torellbreen; (4) Balderfonna; (5) Barentsjokulen; (6) Bivrastfonna; (7) Borebreen; (8) BrSsvellbreen; (11) Chydeniusbreen; (12) Comfortlessbreen; (14) Dahlbreen; (15) Digerfonna; (16) Doktorbreen; (17) Dunerbreen; (19) Eidembreen; (20) Esmarkbreen; (21) Etonbreen; (23) Forstebreen; (24) Fridjovbreen; (26) Glitnefonna; (27) Gronfjordenbreen; (30) Hansbreen; (31) Hellefonna; (32) Hinlopenbreen; (33) Holmstrombreen; (34) Holtedahlfomla; (35) Hornbreen; (38) Isachsenfonna; (40 Kongsvegen; (41) Kronebreen; (42) Kvalbreen; (43) Kvitoyjokulen; (45) Leighbreen; (46) Lilliehookbreen; (47) Lomonosovfonna; (49) Maudbreen; (50) Mittag-Lefflerbreen; (51) Monacobreen; (53) Nansenbreen; (54) Nathorstbreen; (55) Negribreen; (56) Nordbreen; (57) Nordenski61dbreen; (58) Nordmannsfonna; (60) Olsokbreen; (61) Oslobreen; (63) Penckbreen; (64) Poulabreen; (65) Raudfjordenbreen; (66) Recherchebreen; (67) Renardbreen; (68) Rimfonna; (70) Samarinbreen; (71) Sefstrombreen; (72) Sjettebreen; (73) Smeerenburgbreen; (74) Sorbreen; (75) Sorkappfonna; (76) Storbreen; (77) Strongbreen; (78) Stubendorffbreen; (79) Sveabreen; (80) Terre Glac6e Russe; (81) Tunabreen; (83) Ulvebreen; (84) Ursafonna; (85) Uversbreen; (87) Valhallfonna; (88) Vasilievbreen; (89) Vegalfonna; (90) Venernbreen; (91) Vest Torellbreen; (92) Veteranen; (93) Veternbreen; (94) Vonbreen; (95) Von Postbreen; (98) Wahlenbergbreen; (99) Werenski61dbreen. Valleys: (1) Adventdalen; (3) Berzeliusdalen; (5) Colesdalen; (7) Dicksondalen; (8) Dyrdalen; (10) Forkdalen; (12) Gipsdalen; (13) Grondalen; (15) Kjelstr6mdalen; (17) Plurdalen; (18) Purpurdalen; (21) Reindalen; (22) Rijpdalen; (24) Sassendalen; (25) Semmeldalen; (28) Vestfjorddalen; (30) Woodfjorddalen.

SVALBARD

9

10

CHAPTER 1

long after the bay ice has melted. There is an increased supply of bergs from calving in the summer when glacier cliffs are undercut by warmer water. Their distribution is then a product mainly of tides rather than winds at least for the larger and deeper bergs. Figure 1.1 plots the extreme limits of pack ice in summer and winter (see Lunde 1965).

1.3.5

Snow and ice cover

In winter thin snow cover is general with bare patches and thick drifts. This melts throughout the summer leaving bare ice covering about 60% of the whole area above sea level. The larger islands all have ice caps from which glaciers flow, many reaching the sea (Fig. 1.7). The larger icefields are true ice caps, as in Nordaustlandet; the smaller are of 'highland ice' in which the subglacial topography is reflected in the surface contours of the ice. Most mountains also contain independent valley and corrie glaciers.

1.3.6

Frozen ground

Permafrost is defined as permanently or, more accurately, perennially frozen ground. The term is used in different senses. It is most usefully taken to mean that where seasonal melting at the surface occurs a distinctive active zone is separated from the permafrost by the permafrost table. Two terms, not in common use and of Russian origin, may be noted. Pereletok is a mass of anomalous frozen ground within the active zone, and talite is a mass of anomalous unfrozen ground within the permafrost. The formation, temperature, and depth of permafrost are the result of a complex interplay between the microclimatological conditions, the surface cover and the rock beneath, as are the movements that take place within the active zone to form many distinctive types of patterned ground (soil polygons). The sum of all these effects through many years yield a temperature curve with depth from which paleotemperatures may be inferred (section 21.8.4). Permafrost does not occur beneath large bodies of water or ice, so that the undersurface of frozen ground reflects all the above circumstances in a complex manner. In Spitsbergen it is said to have an average depth of 300 m and on Bjornoya only 60 m. Any disturbance of the equilibrium may lead to local phenomena such as pingos, and to frost heaving of man-made structures if adequate precautions have not been taken.

The contemporary (evident) biota (typically visible) Vertebrates Mammals Arctic fox, Alopex lagopus Reindeer, Rangifer tarandus platyrhychus (Musk ox, Ovibos moschatus, recently extinct in Svalbard) Polar bear, Ursus maritimus Seals: hooded, Crystophora cristata; harp, Phoca groenlandica; ringed, Phoca hispida; bearded, Erignathus barbatus Walrus, Odobenus rosmarus Whales: sperm, Physeter eatodon; killer, Orcinus orca; blue, Balaenoptera musculus; white (beluga) Delphinapterus leucas; narwal, Monodon monoceros; minke, Balaena aeutorostrata Birds Diver: red-throated, Gavia stellata Petrel: fulmar, Fulmarus glacialis Geese: barnacle, Branta leucopsis; pink-footed, Anser brachyrhynclus; brent, Branta bernicla Ducks: eider, Somatenia mollissina; king eider, S. spectabalis Waders: purple sandpiper, Calidris maritima; ringed-plover, Charadrius hiaticula; turnstone, Arenaria interpres; sanderling, Calidris alba; grey phalarope, Phalaropus fulicarius Passerine: snow bunting, Plectrophenax nivalis Skuas: arctic, Stercorarius parasiticus; long tailed, S. longicaudus; great, S. skua Gulls: kittiwake, Rissa tridactyla; glaucous, Larus hyperboreus; great black-back, L. mar&us; Sabine's, L. sabini; ivory, Pagophila eburnea Tern: arctic, Sterna paradisaea Auks: puffin, Fratercula arctica; little, Plautus alle; black guillemot, Cepphus grylle; Brtinnich's guillemot, Uria lomvia; common guillemot, Uria aalge Svalbard ptarmigan, Lagopus mutus hyperboreus Fish Arctic char, Salvelinus alphinus Bullhead, Cottus gobio Capelin, Mallotus villosus Cod, Gadus morrhua; burbot, Lota lota Halibut, Reinharditius lippoglosoides Shark: Greenland, Somniosus; basking, Cetorhinus maximus Echinoderms Echinoids, Stronglocentrotus cf. droebachiens& Asteroids Ophiuroids Crinoids

1.4

The biota

Flora and fauna reflect the above physical conditions. The land-based biota is fragile. About 160 species of flowering plants and a few other species occupy low ground and flourish as the snow cover recedes in the short summer, often with spectacular flowers. Grasses may exceed the 15 cm height of dwarf birch and willow. Vegetation directly supports a variety of insects, reindeer and ptarmigan and indirectly the arctic fox. Summerhayes & Elton (1928) made an early study. The marine biota is perhaps the more remarkable. In winter, marine life continues, evident at the surface only by seal, walrus and the predatory polar bear; females hibernate in the snow. Bears number around 5000. With melting of the bay ice in summer, upwelling currents rich in nutrients coupled with continuous daylight generate a prodigious marine food chain exploited by many millions of migrant birds as well as by seal and bear. The birds nest on land and fertilize rich vegetation locally. Ptarmigan overwinter, and occasionally snow bunting and sand piper. The land mammals belong only to three species, fox, reindeer and the polar bear which lives largely off sea ice; voles are recorded at Grumantbyen. A selective list of the more evident Svalbard species follows. Plants, birds, reindeer and bear are protected.

Arthropods Crustaceans Barnacles, Balanus balanoides Crabs and crayfish Ostracodes Arachnoids Spiders and mites Myriapods Insects Spingtails Flies: mosquito; chironomid midges; dragonfly; dameselfly; hoverfly; dipterids Beetles Annelids (oligochaets) Nematodes Molluscs Bivalves Astarte boreal&; A. montagui; A. elliptica; Thyasina flexuosa; Chinocardium ciliatum; Serripas groenlandicus; Macoma calcarea; Lyosima fluetuosa; Saxicava arctica; Mya truncata

SVALBARD

Gastropods Margarites groenlandicas; M. helicinus; Littorina saxatites; Natica clausa; Sipho togatus; Buccinum groenlandicus; B. glaciale; Lora bicanisata; black-winged pteropod, Clio Foraminifers (Nagy 1965) Inner fjords: Cassidulina reniforme; Elphidium clavatum Glaciomarine: Quinqueloculina stalkeri Cyanobacteria, Algae, Fungi and Plants Elvebakk & Prestrud (1996) catalogued 2885 Svalbard species*

Algae and cyanobacteria (1122 spp. recorded*): for example, Laminaria; Lithothamnion glaciale Lichens (593 spp. recorded*) Fungi (624 spp. recorded*) Mosses (373 spp. recorded*) Pteridophytes (7 spp.*) Equisetum arvense; Lycopodium selago Flowering plants-Angiosperms (no gymnosperms) (of 165 spp* 48 from Gaerevoll & Ronning, Flowers of Svalbard, 1980) Arenaria pseudofrigida; Arnica alpina; Braya purpurascens; Campanula uniflora; Cardamine nymani; Cassiope tetragona; Cerastium arcticum; Cochlearia officinalis; Draba corymobsa; D. lactea; Dryas octopetala; Erigeron humilis; Eriophorum scheuchzeri; Melandrium apetalum; M. augustiflorum; Mertensia maritima; Minuartia rubella; Oxyria digyna; Papaver dahlianum; Pedicularis dasyantha; P. hirsuta; Petasites frigidus; Polemonium boreale; Polygonum viviparum; Potentilla chamissonis; P. hyparctica; P. pulchella; Ranunculus hyperboreus; R. lapponicus; R. nivalis; R. pedatifidus; R. pygmaeus; R. sulphureus; Salix polaris; Saxifraga aizoides; S. cernus; S. cespitosa; S. flagellaris; S. hieracifolia; S. hirculus, S. nivalis," S. oppositifloria; S. rivularis; Silene acaulis; Stellaria crasspipes; S. humifusa; Taraxacum arcticum; T. brachyceras

1.5

Political history

In the middle ages, Norwegian kings claimed sovereignty over all land in the Arctic Ocean from Greenland to the Russian arctic islands. In the sixteenth century Spitsbergen became a whaling centre with ships from Holland, England, Denmark-Norway, France and Hamburg. The Dutch settlement, Smeerenburg, on Amsterdamoya was the largest, with peak populations estimated at 200 (or even 1200) persons in the summer. The Greenland whale (Balaena mysticetus) was nearly exterminated in the fjords by 1640 and whalers had to make their catch in the open sea. Of the many claims in the early seventeenth century King Christian IV of Denmark-Norway claimed sovereignty over Spitsbergen, in opposition to the British and Dutch. The Basques of SW France specialised in exploiting the Northcaper whale (Balaena glacialis) and in eighteenth century land-based whaling declined with the whale population, in favour of their migration routes in the open ocean until about 1800 when systematic whaling was finished. From about 1715 to 1850 Russian 'pomors' went to Spitsbergen and wintered to hunt polar bear, reindeer, fox and seal. Norwegians began sealing in Spitsbergen waters in the latter part of the eighteenth century and after c. 1850 without competition. The exploitation of coal began at the close of the 19th and beginning of the twentieth century (Gjelsvik 1968). Early claims to the sovereignty of Spitsbergen by Britain, Holland and Denmark were never followed up. However, competition for mineral wealth continued by many individuals and companies and the map of Spitsbergen was a patchwork of, often optimistic, claims. At the same time scientific exploration by British, French, German, Norwegian and Swedish bodies had heightened the interest in the sovereignty of the archipelago. Arlov (1994) described early negotiations between the Arctic nations in Oslo Conferences 1910 to 1914.

11

The Versailles Treaty makers set about clarifying competing national aspirations when they were arranging protectorates for former colonies. The result for Svalbard was the Spitsbergen Treaty. The history of exploitation in and around Svalbard is outlined more fully in the handbook by Arlov (1989, 1994) and in detail by Hoel (1966).

1.6

The Spitsbergen Treaty

The Spitsbergen Treaty was signed in Paris on 9 February 1920 and Norway assumed administrative responsibility on 14 August 1925. The original signatories were Australia, Britain, Canada, Denmark, France, India, Italy, Japan, Netherlands, New Zealand, Norway, South Africa, Sweden and USA. Other nations followed. e.g. USSR 1924, Germany 1925 later totalling more than 40 signatories. The treaty provides that citizens of these other nations shall enjoy the same rights as Norwegian citizens and as the Norwegian government with respect to access and economic activities on the islands and in the territorial waters. The 10 articles are indicated as follows: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

defines by latitude and longitude, the boundaries of the archipelago, i.e. 74 ~ to 81~ and 10~ to 35~ provides equal fishing and hunting rights; guarantees free access to all waters and to all lands to all signatories; concerns the use of radio; concerns meteorological stations; recognises pre-Treaty rights of ownership and exploration; guarantees equal treatment of all signatories in future acquisition of land and mineral rights; outlines Norwegian intentions with regard to existing mining rights guarantees the neutrality of Svalbard; provides for Russia, then without government, to enjoy the same rights as other signatories.

Procedures for establishing existing claims were laid down under the jurisdiction of a commission to be nominated by the Danish Government (Sindballe 1927). Many other consequences followed from the Spitsbergen Treaty: administrative, strategic, economic/political and environmental.

1.6.1

Administrative consequences of the Treaty

Longyearbyen is the seat of the local administration where the Governor (Sysselmannen) has office and residence supported by police, now mainly helicopter borne. The mining inspector (bergmesteren) is responsible not only for mining operations but also for granting and refusing claim applications and for inspection of claims. The Norsk Polarinstitutt, under the Ministry of the Environment, is responsible for the geological survey of the island and is the Norwegian scientific (including geoscientific) armmainly concerned with the islands. Its former responsibility for topographic and bathymetric survey has been taken over by the Norwegian Mapping Authority (Statens Kartwerk). Appropriate ministries oversee other aspects of the administration such as postal services, radio communications, meteorological stations, building standards and conservation.

1.6.2

Strategic consequences of the Treaty

The strategic situation of Spitsbergen, so evident during the war years 1939 to 1945, and then subsequently in the Cold War between the Warsaw Pact and NATO has been neutralized (Article 9) so that no military establishments nor activities have been permitted.

12

CHAPTER 1

This was monitored by the Norwegian administration and from the Soviet settlements. The exception in World War II was mainly directed to the destruction and denial of facilities to the other side and to placing meteorological stations (Elbo 1952).

The Treaty did not foresee the complications of the off-shore exploration and exploitation of petroleum--it being largely concerned with mineral rights on land. Mineral claims on land were easily regulated by the mining inspector (Bergmesteren) agreeing approximately rectangular parcels each of 10km 2 area, not exceeding about 8 km in length and needing each to be staked, witnessed and claimed with specimens of a mineral to substantiate the claim. In effect this limits the seaward extension of any claim to within 4 nautical miles from a stake at the coastline. At that time, Norwegian maps showed the treaty area delineated by the bounding lines of latitude and longitude (e.g. 1 : 2M NP map of Svalbard 1958). This area was accepted by USSR maps which thus claimed a sector boundary from the NorwayUSSR frontier north along the line of longitude. It was shown to step eastwards between latitudes 74~ and 81~ to accommodate the Treaty area. Subsequently with the advent of subsea petroleum exploration and extended fishing claims far beyond the original 3 mile territorial waters it seemed that the Barents sea (i.e. on the continental shelf) was Norwegian or Soviet. Differences then emerged. On the one

hand Norway claimed a boundary to their part of the shelf based on the equidistant mid-line principle as applied elsewhere in offshore Europe. The USSR followed their meridional sector principle. This created a large disputed zone between the mid-line of the Norwegian government and the sector line of the former Soviet Union. On the other hand the extension of Norwegian continental shelf was held in Norway to override the earlier Treaty area so that the seas 4 miles offshore of the islands within the original latitude, longitude frame were regarded by Norway as outside Treaty jurisdiction. Norwegian maps no longer show this Treaty frame. All these matters have still to be finally resolved, while in the meantime a cooperative spirit in practical economic developments is taking place between Norway and Russia. Figure 1.8 illustrates the political problem accentuated by the economic consequences. The eastern margin of the Svalbard Treaty coordinate area (Long 35~ passes midway between Kvitoya (Svalbard) and Victoria Island (Russia) so that applying the preferred Russian sector principle the sector line running due north from the Norwegian-Russian international boundary on the mainland must be deflected eastwards, as in most Russian maps, to accommodate the Treaty coordinate area. This boundary favours Russia whereas the line median between the national coasts (as applied in the North Sea) passes in a NE direction before joining the same line between the two islands. On the other hand if Svalbard be defined as the archipelago limited to 4 nautical miles offshore, and if the continental shelf, to say the 500m isobath or 200 miles offshore, be applied most of the sea area in the archipelago would be Norwegian as is currently assumed.

Fig. 1.8. Diagrammatic map to show boundaries of possible political interest.

Fig. 1.9. Map showing environmentally protected areas of Svalbard. Redrawn from leaflet issued at Longyearbyen Airport and published by Norsk Polarinstitutt.

1.6.3

Economic/political consequences of the Treaty

SVALBARD

1.6.4

Environmental consequences of the Treaty

Another unforeseen consequence of the Treaty that allows virtually free access by the world's citizens without passport control has been the arrival of many nationalities in unprecedented numbers by cruise liners supplemented by the airport opened in 1975. The pressure on a fragile environment led to the establishing of national parks, bird sanctuaries and other environmental regulations. Thus while there is theoretical freedom of access this can only be permitted within the various necessary regulations and also within the limitations of very few tourist facilities except by sea. Figure 1.9 shows the national parks and nature reserves of Svalbard. Three national parks and three nature reserves, fifteen bird sanctuaries and three plant reserves have been established in Svalbard (see map). No waste may be emptied or left behind in any of the protected areas. The flora and fauna must be protected against injury and unnecessary disturbance. The use of cross-country vehicles is prohibited in the national parks and reserves. Nor are aircraft permitted to land in these areas without the permission of the Governor. From 15 May-15 August it is not permitted to travel within a distance of 300 meters from the edge of the bird sanctuaries. In the Moffen National Reserve all treaffic is forbidden from 15 May to 15 September, both dates inclusive. The ban also includes flying over the reserve at a height of less than 500 meters. All travel on Svalbard must take place in a manner that does not damage or unnecessarily disturb the natural environment. Special care should be exercised in the vicinity of lairs, breeding grounds and nesting sites. The use of motor vehicles is forbidden on thawed ground, and on ground covered by vegetation. There are special regulations for economic or industrial activity on Svalbard. These regulations are printed in the 'Regulations concerning Conservation of the Natural Environment in Svalbard', adopted by Royal Decree of 16 December 1983.

ropeway system long used for transporting coal from mine to loading dock has been replaced by road transport. The University in Svalbard (UNIS) was established in 1995 for one-year courses in Arctic disciplines (biology, geology, geophysics and technology).

1.7.2

1.7.3

Ny-.~lesnnd

Found on the south side of Kongsfjorden, coal was first mined by the Kings Bay Kulkompani A/S (KBKC) in 1917 until 1929 and resumed in 1947. Fifteen men were lost in an accident in 1948, but work continued. In 1960 modernization and extension of the mine was planned but was terminated on 5 November 1962 after an accident in which a whole shift of 21 men were lost. The small town (never more than 300 inhabitants) was then reduced to a small (international) scientific station with a Norsk Polarinstitutt research centre. It has a winter population of 20-30, greatly expanded in the summer by 200 or more visiting scientists and participants in conferences, courses etc.

Barentsburg

Settlements

There is no indigenous population. The principal settlements are based on Norwegian and Russian coal mines with a total population of about 3300 winter inhabitants. There is a large exchange in the summer.

1.7.1

Sveagruva

Located at Braganzavfigen at the head of van Mijenfjorden (in Bellsund) was mined for coal by a Swedish company from 1917 to 1925 when it was sold to SNSK. No mining was done for some years. The installations were destroyed in the war. Mining was resumed but abandoned in 1949 and extensive development (as a satellite mine for Longyearbyen) was planned in the late 1970s. Sveagruva is now the site of the main economic coal mining prospect in Svalbard with accessible reserves estimated at 25 million tonnes and contains one remarkable 5 m thick seam.

1.7.4 1.7

13

Longyearbyen

This is the seat of government of Svalbard and is situated at the head of Adventfjorden south of middle Isfjorden. The coal mine was founded by the American, J. M. Longyear, in 1904 and was worked till 1916. It was then sold to the Store Norske Spitsbergen Kulkompani A/S (SNSK). The earlier mines were in the mountain sides in Longyeardalen and most were destroyed during the 19391945 war. Post-war mines have been developed in mountains along the south side of Adventdalen and Adventfjorden. Coal is mined throughout the winter and stored at Hotellneset for summer shipping when mining ceases giving place to maintenance work. Output has been about half a million tons or less pa. Good facilities for mining personnel have been developed with school, hospital and modern city services. The services are mostly company property. However, the c o m p a n y is increasingly providing for tourists, expeditions and shipping on a commercial basis. The Longyear airport (opened 1975) with scheduled flights to Norway is situated at Hotellneset and there is a good internal road system. Longyearbyen is the principal base in Svalbard for the Norsk Polarinstitutt. The coal reserves, easily accessible from Longyearbyen are being rapidly e x h a u s t e d - the seams being high up in a series of mountains. At the same time Longyearbyen has been developed with an infrastructure, comparable to the best in Norway for a winter population of around 1200 including families. Whereas Sveagruva has coal reserves the investment in infrastructure in Longyearbyen could hardly be duplicated at Svea. The gantry

Located on the western side of Gronfjorden south of the entrance to Isfjorden, is the principal Russian settlement based on a coal mine. It was founded in 1919 by De Russiske Kulfelter. Extensive building was carried out by a Dutch company between 1921 and 1926 who sold it to the Soviet organization Arktikugol in 1932. In the 1930s the settlement was the largest in Spitsbergen. It was destroyed in the Second World War. As the Russian 'Capital' with consul, scientific offices etc. it recently had a population of more than 1000, now 950. Its original reserves have been exploited and mining is extending, by arrangement, into the neighbouring Norwegian claim area. Its economic viability is in question.

1.7.5

Pyramiden

Located at the head of Billefjorden (from northern Isfjorden) was originally a Swedish concession and has been owned by Arktikugol since 1934 [19267]. Construction work began in 1938. The population of about 650 is largely Ukranian.

1.7.6

Older settlements

Earlier settlements based on coal mines and now discontinued include Grumantbyen (FSU, west of Adventfjorden), M u s h a m n a (Norwegian) east of Adventfjorden, Tunheim (Norwegian) on the northeast coast of Bjornoya.

1.7.7

Manned Norwegian radio and meteorological stations

These include the principal station for shipping at Kapp Linn~, at the mouth of Isfjorden, operated from Longyearbyen; also

14

CHAPTER 1 lr~

~

2Ts

/6 ~

/12"

h5 ~

118~

I

'

I

[24 ~

~27 ~

\30 ~

\33 ~

510 80*

0

z~

C>

521

80

79 ~

78 ~

77*

504

/ 76~

76 ~

3G

509

[~501 7 4 o-

0

502 12~ i10o

115o

j20o

Polarinstutt, from catalogue.

at N o r d h a m n a on the north coast of Bjerneya, and at Hopen. Telecommunication from all Norwegian settlements is integrated into the Norwegian system.

publications

Scientific literature on such a small remote area as Svalbard has multiplied not only because of its inherent interest but by virtue of the participation of groups from many nations. A selected bibliography of geoscientific publications appears in part 4 of this volume. Here the the range of official publications is outlined.

1.8.1

Bathymetric

charts

As is customary, charts are under frequent revision while detailed surveys proceed to more remote areas. 12 charts are issued by the N. P (Fig. 1.10). Most other charts are derived from this information. Hydrographic survey is now the responsibility of Statens Kartverk.

1.8.2

Topographic

k.~

1o0

115"

D20 1: 40, 000

118~

/

2G

1:500 000 Sheets

121~

124~

127~

Svalbard 1" 100 000 Sheets

j25o

Fig. 1.10. Sheet lines of charts as originally published by Norsk

Official

4G~

75*

506

1.8

,~, ~ ,

A4 A5 A6 A7 A8 B4 B5 B6 B7 B8 B9 B10 Bll B12 C4 C5 C6 C7 C8 C9 C10 Cll C12 C13 D3 D4 D5 D6 D7 D8 D9

Vasahalveya Magdalenefjorden Krossfjorden Kongsfjorden Prins Karls Forland Reinsdyrflya Woodfjorden Eidsvollfjellet Tre Kroner St. Jonsfjorden Isfjorden Van Mijenfjorden Van Keulenfjorden Torellbreen Mosselbukta Asgardsfonna Austfjorden Dicksonfjorden Billefjorden Adventdalen Braganzav~gen Kvalv&gen Markhambreen Serkapp Storsteinhalveya Gotiahalveya Lomfjordhalveya Vaigattfjorden Hinlopenbreen Negribreen Agardhfjellet

D20 E1 E2 E3 E4 E5 E6 E7 E8 E9 El0 Ell E12 E13 F2 F3 F4 F5 F6 F9 F10 Fll G2 G3 G4 G5 G7 G14 H3 H7 J3

Bjernoya (1:40 000) Sjueyane Nordenski61dbukta Rijp~orden Wahlenbergfjorden GustavAdolf Land Wilhelmoya Kapp Payer Barentsjekulen Freemansundet Guldalen Kvalpyntfonna Tuseneyane H~eya Repeyane Duvefjorden Austfonna Vibebukta Br&svellbreen Berrheia Stonebreen Deltabreen Foyneya Leighbreen Isispynten Isdomen Svenskeya Hopen Storoya Kongseya Kviteya

maps

Topographic maps of Svalbard, published by the Norsk Polarinstitutt (NP) are published on the following scales 1:2000000 1 : 1 000 000 in single sheets; 1:500 000 in four sheets, and 1 : 100 000

Fig. 1.11. Sheet lines of maps (topographical and geological) in both 1" 100 000 series and 1:500 000 series, published by the Norsk Polarinstitutt and redrawn from sales catalogue.

SVALBARD planned for 60 sheets (Fig. 1.11). 1 : 50 000 are available as working dieline prints, with and without place names, and as official maps of various claims and 1 : 2 5 000 map of Bjornoya. There are also some local maps of settlements, mines etc. Map projections are as follows: The 1:1000000 is a conical projection, whereas all other larger scale maps are based on the transverse Mercator projection which is conveniently fitted to the rectangular grid on which the surveys have been based. The grid (essentially the same as used by the British Ordnance Survey) is defined as follows: axis of projection origin of eastings origin of northings Earth's semi-diameters

meridian 15~ 100 km west of axis 8500 km north of equator 6 3 7 8 3 8 8 m and 6356912m.

The origin is therefore false, the point 100000 having the position 15~ 76 ~ 32.89rN. The 1:500 000 map shows 100 squares, but not as above in order to conform to the international U T M series of maps.

1.8.3

Geological maps

These follow the scales, sheet lines and names of the topographic maps (see Fig. 1.11). At scales of 1: 50 000, 1 : 100 000 and 1 : 1 000 000. The principal series is published to the scale of 1 : 100 000 (Fig 1.11). It is planned for sheets to have companion outline texts. In due course these will provide a systematic description of Svalbard geology. In recent years the compilation of these maps and texts from various surveys has been the principal work of the geologists of the Norsk Polarinstitutt, often with international collaboration.

1.8.4

15 Thematic maps

These are also available (on a variety of scales), especially geomorphological. A single sheet 1:400 000 map of mineral claim rectangles is available.

1.8.5

Scientific serials of the Norsk Polarinstitutt

After a number of changes of title the principal multidisciplinary serial is Skrifter of the Norsk Polarinstitutt for monographs published irregularly. Polar Research is for shorter scientific contributions, and the Arbok which continues for internal reports etc. in Norwegian. Skrifter and Polar Research are in English. Meddelelser is of more popular or general nature and has reprinted some work published elsewhere, e.g. translated from Russian. The Polarhdndboker series of small volumes are recommended as introductory companions to this volume: No. 2 (V. Hisdal, 1985, 2nd Edn, Geography of Svalbard); No. 4 (T. B. Arlov 1994, A short History of Svalbard); and No. 7 (A. Hjelle, 1993. Geology of Svalbard), is especially well illustrated with colour photographs and maps. For further superb colour photographs and a further general account see Worsley in Aga et al. (1986), which geological history of Svalbard published by Statoil is a useful introductory supplement to this work. The Norsk Polarinstitutt (NP in this volume) has its headquarters and research facilities currently at Middelthunsgate 29, Postboks 5072, Majorstua, 0301 Oslo with an office in Longyearbyen. From 1997 the institute will move to a somewhat larger organization in Tromso.

Chapter 2 Outline history of geological research W. B R I A N H A R L A N D 2.1 2.2 2.3

2.1

Early exploration, 16 1858 to 1920, 16 1920 to 1945, 18

Early exploration

Useful records of observations perhaps began in 1596 with Barents' voyage and resulting chart. The many expeditions until the middle of the eighteenth century were primarily for whaling with minor additions to the charts. In 1758 A. R. Martin led a Swedish voyage and in 1773 C. J. Phipps commanded a British naval expedition, the first of several, to seek a northeast passage to the Pacific. They penetrated no further than Spitsbergen and made useful observations. At that time and for many years the British Admiralty was concerned with extensive Arctic exploration. The elaborate nature of these expeditions was not so much designed for scientific purposes as for useful employment for enterprising officers, with ships in numbers no longer needed in the period of naval supremacy after 1805. Hydrographic survey was often the principal achievement. In terms of efficiency and Arctic know-how the early whalers such as Scoresby were superior. 1827 may be considered as the year when geological work began, with expeditions from Norway (B. M. Keilhau 1831) and Britain (Capt. Parry, e.g. Horner 1860; Salter 1860). Keilhau, a geologist, visited Edgeoya and Bjornoya. Admiral Parry, Hydrographer of the Navy, wintered on H M S Hecla in Sorgt]orden where further specimens were collected. In 1837 an early Swedish expedition was directed by Lov+n. Then, 1838 to 1840, the French voyage of La Recherche took place under the Commission Scientifique du Nord (e.g. Robert 1840). Only a selection of the many expeditions in the second half of the century are noted here. In 1858 a Swedish scientific expedition included Nordenski61d who later led exploratory voyages with several scientific objectives, including preparatory work for the major international enterprise to determine the Arc of Meridian, as first suggested by Sir Edward Sabine. The main activity was then British, Norwegian, and Swedish, with the first German Arctic expedition in 1868. Arctic scientific exploration had become the international norm. During the years 1850 to the Treaty of S~vres (Paris) in 1920 major expeditions of various kinds include: British 33, Swedish 30, Norwegian 20, German 16, French 6, Russian 4, Austro-Hungarian 2 Dutch, Swiss and American 1 each. From a scientific point of view, distinguished work was done on many of the visits and will be referred to in later chapters.

2.2

1858 to 1920

A series of Swedish investigations led by S. L. Loven (zoologist), D. M. Torell (later Director of the Swedish Geological Survey), A. E. Nordenski61d, and later by A. G. Nathorst and G. de Geer resulted in the first systematic geological knowledge of Svalbard. Thus, whereas previous surveys were essentially for coastal charts (e.g. the British Admiralty chart of 1860), the map of Spitsbergen published in 1865, from field work done in 1861 and 1864, depicted the geological structure throughout the land area, albeit in rudimentary fashion. Nordenski61d's Sketch of the Geology of Spitsbergen (1867, 1876) integrated previous known work, and introduced the name Hecla Hoek. A detailed geological survey was accomplished during Nordenski61d's over-wintering party at Mosselbukta by C. B. Blomstrand (1864) with initial attempts to unravel Hecla Hoek stratigraphy. A further general account with a geological map

2.4 2.5 2.6

1946 to 1960, 19 1960 to 1975, 20 1975 onwards, 21

is found in Suess (1888) Das Antlitz der Erde based on information given him by Nathorst, who, after many published investigations in Arctic palaeobotany by both O. Heer and himself, wrote what was for many years the definitive account of the geology of the archipelago in 1910. Thereafter Swedish work tended to palaeontological studies, e.g. by C. J. J. E. Wiman and E. H. O. A. Stensi6. Nathorst's map (in Suess 1888 reproduced here as Fig. 2.1) distinguished eight rock groups. The Archean outcrops comprise all the more intensely metamorphosed rocks in northern 'Nord-Ost Land', western Ny Friesland and northwest Spitsbergen. The Hecla Hoek System occupies the remainder of the preDevonian outcrop area of less metamorphosed rock. The Liefde Bay System approximates the Old Red Sandstone outcrop and is separated from Archean rocks to the East by a major fault from Billefjorden to Wijdefjorden. The Ursa stage, ('Mountain Limestone', and Permian) corresponds very well to the Carboniferous-Permian outcrop. It is separated from the western outcrop of the Hecla Hoek by another major fault that parallels the coast. The Trias is roughly as now mapped. Cretaceous outcrops, which are largely continental, are not distinguished from Jurassic in this map. The Tertiary outcrops are designated Miocene which was a general opinion then for plantbearing continental sandstones and shales in the North Atlantic Arctic province. A Miocene age was the opinion of O. Heer the leading Swedish paleobotanist who wrote at that time extensively on Arctic floras, which are now mainly regarded as Paleogene. Nathorst's 1910 paper has the systematic structure of a modern monograph on the geology of Svalbard (Beitrdge zur Geologie der Bdren Insel, Spitzbergens und des KO'nig Karl-Landes). The Arc of Meridian project (1899-1902) was a RussianSwedish geodetic enterprise developed from earlier Swedish work. Preliminary investigations for this had been made by Torell in 1861 and 1864. The Swedish section was based on Sorgfjorden and the Russian section on the west coast of Edgeoya. From this remarkably ambitious project flowed many studies, and northeastern Ny Friesland and northwestern Nordaustlandet long continued as Swedish centres for scientific work. Behind much endeavour was the possibility of mineral wealth and political influence in this 'no man's land'. An abortive Swedish attempt was made to mine phosphorite at Kapp Thordsen, as well as early Swedish claims for coal. In view of their outstanding earlier work with Nathorst's palaeobotanical studies up to 1920 it caused some disappointment in Sweden that she was not awarded Spitsbergen at Versailles in the Treaty of Paris. However, at the turn of the century, when the political field was still open, the economic possibility of mineral wealth on land was in many minds. This led to a new surge of interest and, after 30 years of Swedish domination, scientific research became more international and with a competitive edge. After Nordenski61d's expeditions, few had ventured far inland. Interior geology was mostly unknown. Sir Martin Conway with geologist companions, E. J. Garwood and J. W. Gregory (1896), crossed Spitsbergen from Is0orden to Stort]orden and back in 1896. Garwood accompanied Conway the following year. This work contributed to the stratigraphy of central Spitsbergen. The Prince of Monaco arranged expeditions to northwest Spitsbergen in his yacht Princess Alice. The main work, directed by Gunnar Isachsen, was topographic and bathymetric. One object was to connect this triangulation with the Arc of Meridian Survey further east. These voyages afforded excellent geological opportunities. W. S. Bruce, a Scot, joined the vessel in 1898 and 1899 and

OUTLINE HISTORY OF GEOLOGICAL RESEARCH

17

Fig. 2.1. Geological sketch map of Spitsbergen by A. E. Nordenski61d and A. G. Nathorst, E. Suess, 1988, Der Antlitz der Erde, reproduced from E. Suess, The Face of the Earth, H. B. C. Sikes translation 1905, Oxford. Vol. 2, p. 68, Figure 8. returned again in 1906, 1907 and 1909 to explore Prins Karls Forland, which had hitherto been geologically unknown partly, no doubt, because of a lack of evident fossils in rocks. A. Hoel and O. Holtedahl accompanied Isachsen on the mainland work in northwest Spitsbergen and so began a continuing Norwegian

contribution to the Geology of Svalbard. Norwegian independence in 1905 was probably a major influence in the new strength of Norwegian geoscience. Hoel became active in promoting Norwegian interests with respect to the Spitsbergen coal potential and later was responsible

18

CHAPTER 2

for systematic geological surveys. He returned in 1911, 1912 and 1915 and discovered Cretaceous coal between Adventt]orden and Bellsund in 1916. Holtedahl, after work on Carboniferous rocks further south, used this opportunity in the northwest to contribute a first understanding both of the Caledonian nature of rocks previously regarded as Archean and of the Old Red Sandstone stratigraphy and tectonics. H. G. Backlund worked on the basic volcanics and intrusions of the area. Ki~er (1916) defined Devonian strata. Swedish work continued with Wiman's Uppsala expeditions in 1912, 1913 and 1915 to 1917. They resulted in palaeozoological publications especially on Triassic vertebrates and Late Paleozoic brachiopods. Nathorst continued his palaeobotanical studies related to coal deposits of many ages. The Swedish stratigraphical and structural studies might be seen to have culminated in 1910, not only with the publication of Nathorst's monograph, but with the Swedish led excursion of the International Geological Congress from Stockholm led by G. de Geer. The opportunity so afforded led to specialist interest by a wider international community, especially palaeontological. The international exploration for mineral wealth continued with Swedish geologists. In 1916 Birger Johnson led an expedition of 30 to investigate coal in Bellsund, in Pyramiden and in Biinsowland (both beside Billefjorden in Is0orden). Thus the Swedish coal claims were amongst the first of all the claims. Similarly the Scottish Spitsbergen Syndicate (SSS) had made coal and mineral claims. Bruce revisited Spitsbergen in 1912, 1914 to establish these. In 1919 he led a major expedition under SSS auspices and in 1920 a further SSS expedition led by Mathieson was accompanied by several geologists, including G. W. Tyrrell who published various regional studies.

2.3

1920 to 1945

The award of the archipelago to Norway under the Spitsbergen Treaty led to the establishment of the Norges Svalbard og Ishavsundersokelser under the leadership of Adolf Hoel, the forerunner of the present Norsk Polarinstitutt. It had the daunting task, for a small organization, of promoting multidisciplinary studies and organizing the hydrographic, topographic, geological and biological survey of the islands. Results from annual expeditions were published mainly in the new Skrifter om Svalbard og Ishavet. As it happened Hoel was a good organizer as well as a geologist, and the first requirement was to assess the geology of the various mineral claims and especially of the coal fields. With a stable political situation studies proceeded systematically. His own papers were published in 1924 and 1925, and with a summary of earlier Norwegian work in 1929. Norwegian activities 1936 to 1944 were reported (Anon 1945). G. Horn also wrote on the coal of Svalbard (1928), Horn and A. K. Orvin on the Geology of Bear Island (1928) and Orvin in 1934 on the Geology of the Kings Bay region a study of the Ny-Alesund coal field. Bjornoya while much nearer to Norway and generally free of sea ice is hardly more accessible because of the few landing places- none are satisfactory. However, Norwegian expeditions directed by A. Hoel established the coalfield and the general outlines of the geology of the island (e.g. Holtedahl 1920; Horn & Orvin 1928). After preliminary topographic surveys Svalbard was covered by oblique aerial photography in 1936. A major scientific initiative was to record the standard stratigraphic sequence of the Central Basin where the strata at the western limit of the outcrop, between Kapp Linn~ and Gronfjorden, dip steeply at Festningen, at the south western entrance to Isfjorden. Carboniferous to Cretaceous strata are well exposed and a series of detailed descriptions began with Hoel and Orvin's measured section in 1937. This was followed by a rapid succession of about 12 biostratigraphic descriptions of this Festungsprofil from 1928 to 1931 all mainly as Skrifter monographs and mostly by H. Frebold.

Frebold's interest led to his major synthesis published in 1935 Geologie yon Spitzbergen, der Bdireninsel, des K6nig Karl- und Franz-Joseph Landes. (Frebold's geological map is reproduced as Fig. 2.2). Oslo University-based tectonostratigraphic studies were notably advanced through the work of O. Holtedahl (1925) in which the Caledonian interpretation of Svalbard was shown to have close parallels with Scotland. As it turned out later the contemporary assumption that Caledonian Orogeny deformed Early Paleozoic rocks (by analogy with Wales) proved to be misleading in both Svalbard and Scandinavia, where the thick geological successions deformed in mid-Paleozoic time were mainly Late Proterozoic rather than Paleozoic. This misconception hardly affected the tectonic significance of Holtehal's interpretation. Holtedahl also laid the foundation of Devonian stratigraphy in Spitsbergen, of the Ordovician strata in Bjornoya and the geology of the central western Spitsbergen area. Then T. Vogt, in the course of studies of mainly Devonian strata, was the first to note the importance of Late Devonian diastrophism in what he referred to as the Svalbardian folding. Thus two main tectonic episodes were clearly distinguished in Silurian and Devonian time. Swedish work, mainly palaeontological, continued for a time. J. P. J. Ravn (1922) from marine mollusca in the Tertiary coalbearing strata established their Paleocene rather than Miocene age. A. E. Stensi6 (1918-1927) continued his detailed investigation on Devonian fish as also S/ive- S6derbergh (1935-1941) and T. Nilsson (1941-1946). T. H. Hagerman (1925) reported Swedish work in southwestern Spitsbergen in 1924. There was, however, a major expedition in connection with the International Polar Year 1931 to 1932 based in northwestern Nordaustlandet. Of the many results the work of O. Kulling on the Hecla Hoek rocks (1932-1937) provided the first systematic account of Hecla Hoek stratigraphy with description of tillites. The first tillite record had been by Garwood & Gregory (1898) in southwest Spitsbergen. British work took a different turn. From the Scottish Spitsbergen Syndicate exploration for mineral wealth grew a tradition of private expeditions organised in universities, first Oxford then Cambridge. From 1921 to 1938 12 expeditions worked in the northeast sector of Svalbard. While they were mostly multidisciplinary, there was a significant geological contribution. In 1927 on a Cambridge expedition to Edgeoya, N. L. Falcon (1928) first recorded the petroleum potential of Triassic shales. In Ny Friesland, the work of Cambridge geologists on Oxford expeditions, concerned the Hecla Hoek rocks. N. E. Odell (1927) described the unmetamorphosed succession. W. L. S. Fleming and J. M. Edmonds (1941) traversed the Ny Friesland terrane from north to south in 1933 investigating older rocks. P. E. Fairbairn (1933) and Harland (1941) worked on the metamorphic rocks following Tyrrell's (1922) petrological study. The Oxford work, mainly glaciological, then came to be centred on Nordaustlandet, but with a stratigraphic component by K. Sandford (1925-1929). As Kulling had shown that both Nordaustlandet and Ny Friesland had unmetamorphosed Hecla Hoek rocks in common, the question persisted and persists as to the relationship of these strata to the metamorphic rocks that had first suggested an Archean age in the previous century and had been so described by Tyrrell (1922). The International Polar Year in 1934 introduced Polish geologists to Svalbard and they focused their investigations on the southwest sector of Spitsbergen. The work continued in 1936 and 1938, though S. Z. Rozyicki's main work in Wedel Jarlsberg Land was not published until 1959. German expeditions (from Hamburg) visited Svalbard in 1927 (Gripp 1927-1929) and 1935. The earlier one afforded H. Frebold a further opportunity to investigate Mesozoic rocks as well as to continue with glaciological work. Soviet geological work during these years was mainly concerned with their coal concessions and little beyond. From fieldwork in 1932 Ye. M. Lyutkevich published on the Pyramiden coal field geology and D. L. Stepanov (1937) on Permian brachiopods. T. Vogt (1938) wrote on the stratigraphy and tectonics of the Old Red Sandstone deposits. In 1939 a British, Norwegian, and

OUTLINE HISTORY OF GEOLOGICAL RESEARCH

19

Fig. 2.2. Geologicalmap of Spitsbergen reproduced from Hans Frebold (1935). Geologie yon Spitzbergen, de Bdreninsel, des Konig Karl und Franz Josef Landes, 195 pp, Plate 7, in Geologie der Erde, Berlin, Gebrfider Borntraeger, Berlin.

Swedish expedition set out to investigate Devonian stratigraphy and especially to collect fossil fish (Foyn & Heintz I943). From 1939 to 1945 war in Europe brought field work in Svalbard to a close (EIbo 1952). However, the Norsk Polarinstitutt in Oslo continued to function under German occupation and this enabled a synthesizing of results to proceed under Hoel's direction, Notable achievements were A. K. Orvin's (1940) Outline of the Geology and History of Spitsbergen and his monumental Place names of Svalbard (1942, Skrifter No. 80). Similarly H. Frebold continued to work in occupied Denmark and part of his work developed into his Geologie des Barentsschelfes (1951). Geologically irrelevant but of prophetic interest were the polar flights based on Spitsbergen during 1924-25 when Amundson and Ellsworth made a flying boat attempt, and in 1926 they with Nobile flew from Spitsbergen to Alaska in the dirigible Norge. In the same

year Byrd flew to the Pole; and in 1928 Wilkins flew from Alaska to Spitsbergen, the year that the ill-fated Nobile attempt by airship Italia crashed with the loss of some personnel and of Amundson on his rescue attempt. In 1938 Lauge Koch reconnoitred Greenland, from Spitsbergen, for air support for his post-war East Greenland expeditions.

2.4

1946 to 1960

The post war reconstruction of the mines destroyed in the war was a first priority along with the re-establishing of navigation beacons. The Norsk Polarinstitutt (NP) was refounded in 1948 in Olso in succession to the Norges Svalbard - og Ishavs-Undersokelser. One

20

CHAPTER 2

of the last Skrifter (No. 89) to be published under that name from war time compilations was Orvin's Bibliography of literature about

the geology, physical geography, useful minerals, and mining of Svalbard (1947). The organization of the institute and its publications continued with little change except of name and the inclusion in its remit of Antarctic research and with some expansion of staff. Harold Sverdrup (oceanographer) replaced Adolf Hoel as Director in 1940 until his death in 1951 when Anders Orvin, who had been the senior staff and principal geologist, followed as Acting Director until his retirement in 1960. In 1948 the Norsk Polarinstitutt began annual field work in Svalbard for systematic hydrographic, topographic, geodesic and geological surveys, as well as research in other disciplines. Since 1948 the Norsk Polarinstitutt has been the leading Svalbard research institution for geology, as well as for many other disciplines. Early postwar research, focused at first on Sorkapp Land where, in the enigmatic 'Hecla Hoek' rocks, Cambrian and Ordovician fossiliferous successions were reported by H. Major and T. Winsnes (1955). Operational research on the Tertiary coalfields was continued by Major, with palynological investigations by Manum (1954 and 1960). A dictionary of all named and published stratal units of Svalbard was prepared by Major et al. (1956) as part of the French inspired International Stratigraphic Lexicon. Paleontological studies continued in the University Museum, Oslo (e.g. Wangso 1952). In 1956 in connection with the third International Geophysical Year, Polish work under the leadership of S. Siedlecki resumed in Wedel Jarlsberg Land between Bellsund and Hornsund from a new base (Ibjornhamna) on the north shore of Hornsund. While the earlier work was published, new work led by Birkenmajer and his team described the complete stratigraphy along the north of Hornsund (1958-1959). This usefully complemented the work by the Norsk Polarinstitutt in Sorkapp Land just south of Hornsund. The new features of this work; in addition to confirming fossiliferous Cambrian and Ordovician strata (e.g. Kielan 1960) was to formulate a long sequence of Precambrian strata and tectonic events supported by petrological studies with suggestions of granitization (Narebski 1960, Smulikowski 1960). Almost continuous multidisciplinary Polish work since then is recorded in the works of Birkenmajer and his colleagues. The combined results of the Norwegian and Polish work were presented to the members of the excursion of the 1960 International Geological Congress. During this excursion footprints of Cretaceous Iguanodon were demonstrated (e.g. de Lapparant 1962). In the meantime private ventures from a number of British universities had been active and indeed resulted in the larger number of geological publications during these 15 years. Birmingham groups in 1948, 1951, 1954 and 1958 worked in southern Oscar II Land between Isfjorden and St Jonsfjorden where slices of Carboniferous and Permian strata with distinctive fossils are tightly compressed with Precambrian strata (Baker Forbes & Holland 1952). In addition to structural studies (Weiss 1953, 1955, 1958) Carboniferous and Permian strata were described (Dineley 1958). The problem of distinguishing deformation structures that are preCarboniferous from post-Permian became evident and persists. Devonian rocks with fish in Ekmansfjorden were also introduced (e.g. Dineley 1955, 1960; Barr 1960). Atkinson of Imperial College, London worked in Prins Karls Forland in 1950, 1951, 1953 and mapped the area in more detail than previously (1952-1963). Oxford work was largely glaciological and Sandford continued to publish results from earlier field work, and new aerial photographs (1950-1963). From the Queen's University, Belfast, work between Isfjorden and Kongsfjorden further elucidated understanding of the Precambrian strata (Bates & Schwarzacher 1958; Preston 1959). From Durham University a party investigated inner Kongsfjorden, and A. Challinor, one of its members, later joined the Cambridge group. This Cambridge group (CSE) led by W. B. Harland first arranged a small party in 1948 to investigate the Scottish Spitsbergen Syndicate properties in Btinsow Land. This was followed in 1949 by Carboniferous and Permian studies (Gee, Harland & McWhae

1953; Forbes 1960; Forbes, Harland & Hughes 1958). The structural problem of the Billefjorden Fault Zone was addressed by McWhae (1953). It then seemed to be initially a compressive thrust fault system. Most effort was devoted to the survey, topographical as well as geological, of Ny Friesland to determine the Hecla Hoek succession and its relation to the schists and gneisses occupying the western part of the Land. This was an old problem. It seemed to be solved by extensive reconnaissance mapping which showed a relatively concordant sequence of about 18km of strata in which the metamorphic rocks comprised the lower part. No major unconformity had then been demonstrated (Harland & Wilson 1956) and the Caledonian deformation and deep burial seemed to account for the tectonic contrasts (Harland 1959). The succession was first divided into Lower, Middle and Upper Hecla Hoek; the Lower being metamorphosed (Bayly 1957), the Middle only partly so (Wilson 1958 and posthumously 1961), and the Upper part in two groups a lower tillite-bearing group (Wilson & Harland 1964) and overlying Cambrian and Ordovician strata - the first fossils, Salterella rugosa, being found by Wilson in 1955 and then a richer Ordovician fauna (Gobbett 1960; Gobbett & Wilson 1960; Hallam 1958). Investigations of this rich succession had only just begun by 1960 and it already had become, perhaps prematurely, a standard for comparison and correlation of Precambrian rocks elsewhere in Svalbard (e.g. Harland 1960). In 1958 palaeomagnetic collections throughout the unmetamorphosed rocks of the area were made by D. E. T. Bidgood for comparison with Greenland (Bidgood & Harland 1961) but the samples proved to be unstable. Beginning in 1951 and 1953 the structures in the Old Red Sandstone, west of Wijdefjorden, had been noticed overlying the Billefjorden Fault Zone (as later named) and P. F. Friend began his investigations of the Old Red Sandstone rocks in 1955 and continued in 1958 and 1959. His main work and the published results followed from 1960 onwards (e.g. Friend 1961; Friend & Moody-Stuart 1972). At this time although Soviet Geologists were not active far outside the coal concessions their prominence in continental and global map compilations in Moscow inevitably led to the need to include Svalbard and so interpret its structure. An example is Klitin's (1960) paper on the tectonics of Spitsbergen with its prevailing fixist interpretation and a network of deep-seated faults dividing the terranes.

2.5

1960 to 1975

A major change in Svalbard research came about with the industrial interest in the petroleum potential in the Barents Shelf. In 1960 the Shell Oil Company addressed the possibilities and AMOSEAS (a consortium of Chevron and Texaco in the US) undertook their own systematic investigations. A new era of logistic support, previously unthinkable, with helicopters and skidoos was introduced replacing to a large extent dependence on small boats, man-hauled sledges and pack-carrying. Larger vessels continued to be essential for logistic back-up. These changes coincided with the general acceptance of standardised international conventions, especially in stratigraphic nomenclature. Previously, as with place names different groups had developed their own mainly European practices and the recently developed North American Stratigraphic Code which, for rock unit nomenclature formed the basis of the international standard, had the effect of focusing stratigraphic work on the whole rock unit rather than on the interesting beds or fossiliferous niveaux. Probably another consequence of this American petroleum influence was the decision in the USSR to match this new scientific input. From then on each year Soviet geological parties each of three or four, with heavy camps suited to the Soviet Arctic, were deposited by large helicopters according to a systematic programme throughout Svalbard. The Soviet tendency was to work

OUTLINE HISTORY OF GEOLOGICAL RESEARCH independently and produce their own confidential maps of the whole region. Many results were published, but at first detailed maps and other records were not available as was also the case with the western petroleum companies. Sokolov (1965) and Krasil'shchikov (1973) synthesized results of the older rocks. Until about 1960 practically all geological work had been of a reconnaissance nature and the different areas of interest that tended to be the province of one research group were not trespassed upon by other groups. This had the effect that any geological synthesis tended to be a compilation of different components each generated by a differing outlook. From about 1960 onwards territorial preserves ceased and there was enough geological personnel for the main groups each to extend elsewhere in whole region. This certainly applied in different ways to oil company exploration, the Norsk Polarinstitutt, the Soviet presence mainly organized through the Institute for the Geology of the Arctic in Leningrad, the Polish work mainly in the south and, with less resource, to the Cambridge group which graduated from small open boats and man-hauled sledges to enclosed motorboats. The Norsk Polarinstitutt had in 1960 a new Director, Tore Gjelsvik. His emphasis was first to ascertain whether any mineral resources had been overlooked. Geological publications during this 1960-1975 period were at a rate more than three times that of the preceding 15 years. Increased output tends to submerge significant scientific developments. Groups centred in Oslo, Leningrad and Cambridge were each comprehensive in their interests and similar in output. The Polish group on the other hand focused on the southern part of Spitsbergen. This had the advantage of more thorough connected studies but lost in some appreciation of their regional context. By 1975 all areas of Svalbard had been described in some degree, some areas by more than one group. Stratigraphically rock units had been named consistently with more or less standard descriptions of the strata, based on innumerable measured sections and so with a systematic view as to their local variation. Individual palaeontologists, especially in France and Germany as well as in the other groups, described more and more fossils from the rich horizons. Devonian fish were investigated especially in Oslo and Paris. A new Ordovician fauna was discovered in northeast Ny Friesland first by Cambridge and later investigated by the Natural History Museum in London and the University Museum in Oslo. The ubiquitous coal and plant bearing strata were the subject of palaeobotanical studies which were largely done in Germany whereas palaeontological investigations were active in Cambridge, Oslo, and St Petersburg. Mesozoic ammonites were described in detail in Hamburg, St Petersburg, and in England. CarboniferousPermian faunas were described especially in Poland, Britain and Soviet Union. Moscow palaeontologists made comparisons of stromatolites, oncolites and phytolites with Late Riphean sequences in the Soviet Arctic. Mineral occurrences and geochemical studies were especially undertaken in the Norsk Polarinstitutt, but are of genetic rather than economic interest. Petroleum prospects were explored with deep wells in Spitsbergen, Edgeoya and Hopen (Appendix). Perhaps the result of these 15 years work was to remove the early optimism about the land areas of Svalbard as good petroleum prospects. Source rocks occur; but tectonic compaction and sedimentary facies and erosion have reduced the likely petroleum content of the reservoirs. Since then the main interest of Svalbard to the petroleum industry has been as a sample of the strata already being delineated by seismic and other surveys in the Barents Sea. Coal, petroleum and mineral exploration are discussed further in the appendix. The better understanding of the local geology provided a platform for informed tectonic studies. These 15 years corresponded with the conversion of a majority of geologists to accept hypotheses of continental drift with the early development of plate tectonic interpretations. In such studies Svalbard played a key role from the very beginning. The detailed separation of Spitsbergen from north of Greenland with the complex opening of the Norwegian Greenland ocean basin, and the (simple) spreading

21

about the Nansen-Gakkel Ridge to form the Arctic Ocean Basin were amongst the first kinematic results to be established. They had indeed been anticipated by Wegener (1924), Taylor (1928), du Toit (1937) and by Carey (1958). Svalbard data yielded one of the first instances where palaeocontinental drift was argued with the closing of the Iapetus Ocean that separated Greenland with Svalbard from Norway and the Baltic Shield. Major Devonian sinistral strike-slip had already been suggested (Harland 1965) to move Svalbard from central East Greenland to the south of north Greenland and by 1971 sinistral transpression (and transtension) along the Billefjorden Fault Zone had been identified. The long history of this fundamental fault was documented in 1974. By 1975 it was suggested, not only on the basis of structures, but mainly on that of contrasting stratigraphic sequences in distinct terranes, that Svalbard now comprised at least three major allochthonous terranes with subterranes, separated by at least two fundamental strike-slip fault zones. The allochthonous terrane concept elsewhere in the world became generally accepted and was gradually applied by more scientists in Svalbard (see section 3.5). Svalbard was also noteworthy because of the ubiquitous diamictites, which contribute excellent evidence for the global Varanger (late Vendian) ice age, for long doubted but now generally accepted. The two distinct Varanger tillite horizons are recognizable in all three Svalbard provinces or terranes, thus giving a basis for wider correlation. Subsidence of the Hecla Hoek geosynclinal basin by thermal contraction of the mantle was also one of the early suggestions of a mechanism (Harland 1969) that has since become rigorously established but in this case on a far longer time scale. Whereas the deformation of strata up to early Paleocene in age along the western margin of the Central Basin had long been established (e.g. Orvin 1934, 1940) new reconnaissance demonstrated a far more elaborate fold and thrust belt than had earlier been anticipated. This investigation of the structure of PostDevonian strata was led by A. Challinor (e.g. 1967 and Fig. 20.8). The West Spitsbergen Orogen was so defined (Harland & Horsfield 1974). The immense interest of these structures has subsequently resulted in a flood of publications (e.g. Dallmann et al. 1993a). During the late 1960s and early 1970s the availability of helicopter platforms on ice-strengthened ships enabled renewed reconnaissance of the eastern islands of Svalbard by Norwegian and Cambridge parties (see especially Chapter 5).

2.6

1975 onwards

The all-weather Longyear Airport was opened in 1975 and thereafter contributed to the increasing scientific activity, not least by enabling field work to increase at the expense of travel time. The rate of publication of serious geoscientific work relevant to Svalbard continued to increase to more than 50 significant geoscientific publications a year. A notable change was the participation of many American and then Japanese scientists so that Svalbard ceased to be so conspicuously a European scientific arena. Whereas hitherto much of the stratigraphic endeavour had been unsophisticated, a new onslaught with sedimentological expertise and palaeogeological interpretations now becomes the rule. Similarly a more rigorous discipline in structural geology was applied so that far more information was obtainable from a local study than previously. Thus the intensive structural studies within and beyond the West Spitsbergen Orogen mushroomed with investigations dominated by Norwegian and American geologists as summarized by Dallmann, Andresen et al. (1993). New palaeontological techniques were brought to bear so that, for example, the immense mass of Hecla Hoek rock of the Ny Friesland geosyncline, hitherto thought to be mostly barren, yielded fabulous detail of microbial remains preserved in chert going back hundreds of millions of years into Precambrian time (e.g. Knoll 1982, 1985).

22

CHAPTER 2

Submarine and aerial surveys by industry were becoming available. Seafloor spreading sequences for the Norwegian Greenland seas in particular for Cenozoic configurations were worked out in detail with adequate control especially in the University of Bergen with its strong geophysical divisions. Microseismic cooperation between American and Norwegian seismologists began to map out the contemporary stress-strain adjustments in Svalbard with perhaps unexpected results (e.g. Mitchell et al. 1990). A local matter, but significant from the author's point of view, was that while hitherto the Cambridge group had enjoyed active cooperation for Svalbard research with the petroleum industry in Norway, it became understandable Government policy to recommend companies seeking concessions to commission work from Norwegian institutions and this acted positively to encourage the Cambridge group to extend their comparisons with the Soviet, Canadian Arctic and Greenland (the author having worked a little with Lauge Koch). So in 1975 the Cambridge Arctic Shelf Programme (CASP) was formed and Cambridge Svalbard Exploration (CSE) was slowly merged with it. The scientific consequence was to focus on the whole Arctic in which Svalbard would always be a key element. From being a personal charitable enterprise, CASP became a company limited by guarantee with charitable

status in 1988. As such, its prime object continues namely research, publication and education. The Norsk Polarinstitutt under its new government umbrella, the Ministry of the Environment, led by the Chief Geologist, W. K. Dallman pursued a vigorous policy, giving priority to the systematic completion of the 1 : 100 000 geological map series, each with an accompanying explanatory text. In this programme foreign geologists were invited to participate both in comment and criticism and as joint authors. For many years the Norsk Polarinstitutt had arranged logistic support for groups engaged in local mapping projects, but the new policy gave the international community an opportunity to engage in cooperative research. It had long been policy that mapping, both topographic and geological, should be organized by the Norsk Polarinstitutt. This volume may be seen to mark the fulfilment of the reconnaissance phase of Svalbard geology as recounted above. The future is exploding with detailed and systematic investigation of the archipelago according to new and more rigorous standards and certainly with participation of scientists from many countries increasingly coordinated by and cooperating with the Norsk Polarinstitutt. One example is the publication in English of Russian work, some previously unpublished (e.g. Krasil'shchikov 1996).

Chapter 3 Svalbard's geological frame W. B R I A N 3.1 3.1.1 3.1.2 3.1.3 3.1.4 3.1.5 3.2 3.2.1 3.2.2 3.2.3 3.3

The space frame: Svalbard's structural frame, 23 Solid outcrops, 23 Regional descriptive sectors, 23 Discontinuities as convenient boundaries, 23 Structure of Svalbard, 25 Kinematic interpretation of Svalbard's history, 25 The time frame, 25 International time frames, 25 A provisional time scale, 28 Svalbard's chronometric record, 29 The rock frame, 29

This chapter gives an outline of the geology of Svalbard, an introduction to the principles applied in this work and a preview of the interpretations and conclusions that have come out of these studies. The key position of Svalbard in relation to other Arctic lands is shown in a Polar projection (Fig. 3.1).

3.1 3.1.1

T h e s p a c e frame: S v a l b a r d ' s structural f l a m e Solid outcrops

The conventional geological map of Svalbard shows in outline the outcrop areas according to age. (Fig. 3.2). Although rock ages are matters of interpretation, the diagrammatic map is at least consistent with the conclusions in this work. It differs from most maps in the larger outcrop of Vendian rocks within the basement. The outcrop pattern ignores Quaternary deposits, i.e. it is a solid geology map. It is diagrammatic because detail is impossible to show on this scale. The larger ice masses which obscure the exposure are also diagrammatic.

Fig. 3.1. Svalbard in the Arctic (polar projection), based on various sources. Greenland has been officially divided as indicated by the dashed boundaries and initials, EI is Ellesmere Island; NS is Nares Strait.

HARLAND 3.3.1 3.3.2 3.4 3.4.1 3.4.2 3.4.3 3.5 3.5.1 3.5.2 3.5.3 3.5.4

3.1.2

A lithic code, 29 Some practical stratigraphic conventions in this work, 31 Teetonostratigraphie terranes and their sequences, 31 The terranes and their sequences, 32 Combined sequence for Svalbard, 36 Sequence stratigraphy, 37 Geotectonic interpretations, 37 Provinces and allochthonous terranes, 37 Differential horizontal lithosphere motions, 38 Polar and lithosphere wander, palaeoclimates, 40 Differential vertical lithosphere motions, 43

Regional descriptive sectors

Because the intention in this work is generally to describe rocks before interpreting their history and so not to begin with too many assumptions, the rocks are described in Part 2 of this work in the eight sectors or regions (Chapters 4 to 11) as shown in Fig. 3.3. Their boundaries are not fixed because it is convenient to treat some geological matters together in one chapter, even when they might overlap onto another. They are not terranes. Where strata are described the succession is presented as observed with the youngest at the top (as in Part 2). When the sequence is interpreted later (as in Part 3) the earliest events precede the later.

3.1.3

D i s c o n t i n u i t i e s as c o n v e n i e n t b o u n d a r i e s

Some boundaries on the geological outcrop map are important discontinuities. These are mainly fault zones or lineaments and some are fundamental in the sense that they dip steeply and persist through long spans of geological time. Other boundaries are perhaps equally significant as unconformities which, generally dipping gently, do not appear as fixed lineaments on a map.

24

CHAPTER 3

SVALBARD'S GEOLOGICAL FRAME Figure 3.4 depicts important named fault zones or lineaments as continuous lines. Dashed lines indicate the major unconformity between the older (pre-Carboniferous rocks) and the younger postDevonian strata. The fault abbreviations listed in the caption to the figure may be used throughout this work. These boundaries separate descriptive terranes or subterranes as listed in Section 3.4.4 with their distinct tectono-stratigraphic sequences.

3.1.4

25

/

I/

/

1/2 ~

I

16 ~

/

2 0 c"

28 ~

24 ~

Structure of Svalbard

32 ~

/

I

.%

l

Figure 3.5 shows Svalbard in relation to the structural elements of the Barents shelf and especially the position of Bjornoya in that context. Figure 3.6 shows diagrammatically the structure of the rest of Svalbard according to the interpretation of Russian geologists (Krasil'shchikov, Abakumov et al. 1996). It is a useful summary of one viewpoint which assumes that the structural elements of Svalbard as seen now have persisted in that relationship through geological time. It is therefore a basis from which kinematic interpretations of Svalbard's history that led to the present configuration may be explored.

5

~

3.1.5

!i

Kinematic interpretation of Svalbard's history

Postulated successive spatial arrangements in a palinspastic sequence depend on interpretation of similarities and contrasts between terranes, not only in Svalbard. These may be speculative or controversial postulates and are reserved for Section 3.5 in this chapter. However, it is one of the objectives in Earth history to elucidate past movements between lithospheric plates. The description of Svalbard tectono-stratigraphic sequences is therefore arranged here in the terranes selected for convenience in discussing palinspastic possibilities without prejudice as to their prior configuration. Should Svalbard, as concluded later, be the result of juxtaposition of far-travelled terranes deriving from distinct provinces the exercise may be worthwhile even if it be contradicted by new evidence. But this discussion is for Section 3.5 and is touched on especially in Chapters 12-15 in Part 2.

KEY

"i

I

11

0 I

krn I

I O0 I

Fig. 3.3. Regions of Svalbard as used in this book for Chapters 4-11, with the general extent of coverage for particular chapters in Part 2. The numbers refer to the numbered chapters as follows: (4) Central Basin; (5) Eastern Platform; (6) Northern Nordaustlandet; (7) Northeastern Spitsbergen; (8) North central and northwestern Spitsbergen; (9) Central western Svalbard; (10) Southwestern Spitsbergen; (11) Bjornoya and related submarine shelf.

Neogene plateau lavas

Silurian-Devonian plutons

Paleogene

Cambrian-Ordovician

3.2

Early Cretaceousbasites

Vendian

3.2.1

EarlyCretaceous

Late Neoproterozoic

There are two elements in the standardization of international geological time: chronostratic and chronometric (Harland et al. 1990).

Jurassic-Cretaceous dolerites

Early Neoproterozoic granites

~

Jurassic

~

Triassic

Early Neoproterozoic volcanics ?Early Neoproterozoic granites and migmatites

Carboniferous-Permian /

Late Paleoproterozoic basement

~

[~

Devonian Fig. 3.2. Generalized geological map of Svalbard, from various sources and this work.

The time frame International time frames

Chronostratic scale. This scale, commonly referred to as the stratigraphic scale, began nearly 200 years ago as a sequence of geological events, even catastrophes, which divided Earth history into natural chapters. These packages of strata, developed step by step, into the geological systems with their series and stages. When it was assumed that there was a definite identifiable body of rock constituting a system it was logical to divide it into upper, middle and lower etc. It was inherent in this thinking that rocks existing today (i.e. in Holocene time) could be interpreted by superposition processes as formed in successive earlier times. 100 years later it became evident that the stratal record did not divide globally in an easily identifiable way and the problem became

26

CHAPTER 3

Fig. 3.4. Principal discontinuities in Svalbard. Fault lineaments: (BBF) Breibogen Fault Zone: (BFZ) Billejorden Fault Zone; (HBF) Hannabreen Fault; (KHFZ) Kongsfjorden-Hansbreen postulated fault zone; (KVL) Knipovich Lineament; (LFZ) Lomfjorden Fault Zone; (RFF) Raudfjorden Fault Zone; (VL) Veteranen Line; (WSTF) West Spitsbergen (orogenic) Thrust Front. Major unconfomities with relevant age indicated by dashed lines and a dotted line.

one of the correlation of essentially diachronous boundaries. Then after another 50 years it was realized that for international agreement to use the same boundaries it was necessary to standardise each b o u n d a r y at only one point (the GSSP = Global Stratotype Section and Point) or 'golden spike' (Cowie 1986; Cowie et al. 1986; R e m a n e et al. 1997). Moreover, this point was to be defined geometrically in strata and was to be interpreted as a point in time (e.g. the m o m e n t of deposition o f that sand grain). Elsewhere any rock age should be expressed as earlier or later than this point event. The age o f rock elsewhere is thus never certain, but rather for estimation and judgment. This changes with changing technology. As far as possible the traditional stratigraphic divisional names were applied and are being standardized in this way. Perhaps one consequence of this procedure, not yet c o m m o n l y applied, is that ages o f most rocks are estimated by time correlation from the standard and the time scale is expressed as time, i.e. early and l a t e - no longer lower and upper. The practice was applied (e.g. t h r o u g h o u t in H a r l a n d et al. 1990) without dissent and should be applied t h r o u g h o u t this work. The concept o f a geological system as a chronostratic division is operationally o u t m o d e d . It exists, but its exact boundaries c a n n o t be k n o w n and therefore c a n n o t be a standard. The international c o m m u n i t y is working towards the standardization of such a chronostratic scale and its current state is

Fig. 3.5. Major structural features of the western Barents Shelf, based on fig. 3.1 of Vorren et al. (1991), Marote Petroleum Geology, 8.

tabulated broadly in Fig. 3.7. The details, where relevant, will be discussed period by period in Chapters 12-21 in Part 3. We observe rocks that can properly be divided as needed into lithic units: lower, middle and upper. The code for their use, as far as this work is concerned, is outlined in Section 3.3. below.

The chronometric scale. This, c o m m o n l y referred to as t h e numerical scale, is the generally used scale in years. It is far from absolute in its application to rock. Only two elements are required for international agreement (i) the standard for the unit of time and (ii) any classification of spans of such units and their names. (i) A year no longer depends on the standard year of the International Astronomical Union, but on its calibration in seconds as defined by the International Union of Weights and Measures in terms of perturbations of the cesium atom. These refinements are irrelevant for geological estimates of age. All ages may be expressed numerically, commonly for pre-Pleistocene stratigraphy in millions of years. The convention in this work is that Ma stands for an age, i.e. so many million years before the present. (ii) However, the second requirement is optional, i.e. to name specified intervals of time defined, not by GSSP but by an exact number of years. For the rock record in Precambrian time this has been agreed by the International Union of Geological Sciences. These names are appended here. There are numerous technical reasons why numerical estimates of age can hardly be true ages but rather apparent ages, which is only one reason for not regarding them as absolute. Even the errors properly quoted merely measure the limitation of the laboratory results and ignore the many other uncertainties arising from the geological history and relationships of the sample. The

SVALBARD'S GEOLOGICAL FRAME )MM & LM.t

27 !

!

12 ~

\ 30 ~

21 ~

_80 ~

ilia+

+ + +1|

++++++ +++++ ++++++

+++++) NORDAUSTLANDET

~79 ~

79 ~ ~O~ G ~

~

78 ~-

-78 ~ SPITSBERGEN

EDGEC)YA Folded b a s e m e n t

~

Devonian molasse

complex

~

Platform cover Major f a u l t zones

-77 ~ ~IU.

77 ~-

~ A x e s of a n t i c l i n e s (a) and s y n i c l i n e s (b)

Hopen

I North-East uplift II Nordenski6ldbukta anticlinorium:

1 PrinsOscars Land horst-anticline 2 Lovdn syncline 3 Nordkapp anticline III Hinlopenstretet synclinorium Ilia Eastern limb IIIb Western limb

Fig. 3.6. Major structural elements of Svalbard, a Russian interpretation. Redrawn with permission from Krasi'shchikov et al. (1966). Main features of the Geology of Svalbard in Krasil'shchikov (ed.) Soviet geological research in Svalbard 1962-1992, extended abstracts of unpublished reports, Meddelelser, 139, Norsk Polarinstitutt, Oslo, pp. 14-15.

4 Floraberget anticline 5 L~goya synciine 6 Kinnvika syncline 7 Sveanor syncline 8 Sparreneset syncline 9 Heclahuken anticline 10 Kluftdalen syncline 11 Gulfaksbreen anticline 12 Veteranen syncline 13 Kvitbreen syncline IV Wester Ny Friesland anticlinorium:

14 Atomfjella anticline 15 Bangenhuken anticline V North-West uplift:

16 Richardvatnet anticline 17 Sn~fjella syncline

following scale though endorsed by the IUGS, confuses latinized event names with precise numerical definitions and may gradually be superceded by the chronostratic scale as it extends backwards into Precambrian history except for the names and divisions in bold letters and numbers. Other ages are given by number.

I

!

I

Major basement structures:

30 ~

21 ~

12 ~

18 Krossfjorden anticline 19 Blomstrandhalvoya graben-syncline 20 Mitrahalvoya syncline Vl West coast horst-anticlinoriun: 21-26 minor synclines:

21 Bulltinden 22 Alkhomet 23 Kapp Lyell 24 Sofiekammen 25 Luciakammen 26 Hornsundtind

Major structures of Devonian complex and platform cover: vii Devonian graben of Andrde Land:

27 Inner horst 28 Andree Land anticline VIII West coast horst-like uplift: 29-33 superimposed graben-troughs:

29 Kongsfjorden 30 Forlandsundet 31 Renardodden 32 Hornsundneset 33 Oyrlandet 34 Olsokbreen swell

IX West-Spitsbergen graben-like trough:

35 Iradalen depression 36 Holmsenfjellet swell 37 Skiferdalen depression 38 Reindalen swell 39 Tverrdalen depression 40 Bettybukta depression 41 Isbukta swell X Sassendalen monocline XI East-Svalbard horst-like uplift:

42 East-Spitsbergen depression 43 Barentsoya-Edgeeya swell

Major fault zones: 1-4 fault zones:

1 Western marginal zone 2 Eastern marginal zone 3 Pretender zone 4 Erdmannflya-Bohemanflya zone 5-9 faults:

5 Raudfjorden-Kronebreen 6 Bockfjorden-Ekmanfjorden 7 Lomfjorden-Agardhbukta 8 Hinlopenstretet 9 Duve~orden

Precambrian Chronometric Scale as defined internationally (Table 3.1). P h a n e r o z o i c is n o t classified chronometrically. The initial C a m b r i a n b o u n d a r y is defined in G S S P in N e w f o u n d l a n d , therefore the age (here at 545 Ma) is a current estimate a n d n o t a definition (Tucker & M c K e r r o w 1995).

28

CHAPTER 3

Table 3.1. Precambrian chronometric scale Neo-Proterozoic III

Eon

Neoproterozoic

Pedod

Era

650 Ma

O

Cryogenian

N 0 r-

Tonian 1000 Ma

(J

Epoch

Quatemary

Q

Neogene

Ng

Paleogene

Pg

Stenian K2

Ectasian Cretaceous

1400 Ma

K1

Calymmian 1600 Ma Statherian

J3

1800 Ma o

2050 Ma

N 0 O0 (I)

Rhyacian 2300 Ma

Jurassic

J2

2800 Ma Tr 3

Mesoarchean

3.2.2

Triassic

3200 Ma

O

3600 Ma

O N O n,' uJ Z < "T" EL

A provisional time scale

The above international conventions simply inform us how to use names and numbers. However, the calibration of the chronometric by the chronostratic is always a scientific problem that is never finally soluble. A time scale is thus one of many attempted calibrations (in years) of the chronostratic scale. Ages of events are often quoted in years without calibration as though the calibration is an established fact. With so many time scales in use it was decided to make a single justified scale so that Svalbard history could be discussed within one group (CASP) at least on a common basis. This was first completed in 1982 and a more thorough revision attempted in 1989 (Harland et al. 1990). The attempt was made to apply the latest or most likely international, rather than regional, nomenclature and classification. The Cambrian and consequently parts of the Ordovician scale were especially weak at that time owing to lack of good determinations. A new crop of U - P b zircon ages has since greatly strengthened this part of the scale as reviewed by Tucker & McKerrow (1995). The accompanying Fig. 3.7 combines the two scales referred to above so that the later values replace the earlier ones wheresoever they can be applied throughout Cambrian, Ordovician and Silurian time. Otherwise the scale is as published in 1990. In making this composite scale without the many other improvements an important principle is at stake: a published calibration is of little use if the reasoning behind it is not clear. In this case the data and arguments are available in Harland et al. (1990) and in Tucker & McKerrow (1995). It is the intention that this scale be used throughout this work for comparison and consistency; but not with any suggestion that it is correct or even the best. In any case these new data from Newfoundland and Britain are reasonably consistent with somewhat earlier determinations from Russia (Bowring et al. 1993; Knoll et al. 1995)9 Figure 3.7 is simplified for use in Svalbard where asterisks mark ages which have some biostratigraphic basis. Rocks thought to be more than 1000Ma old have not yet yielded fossils and age estimates depend entirely on isotopic determinations. Figure 3.8 tabulates some of these critical data. Improvements will continue indefinitely. One chronostratic change referred to in Chapter 14 is that the Llandeilo division may well be subsumed as Llanvirn

8.5 32 15

"k

13 7 14

132 146

Kimmeridgian W Oxfordian -k

11 157

"k W

Bajocian

21 178

30

Hettangian

4000Ma

12.0 21.0

97 "k * -k

Tr 2 Tr 1

Permian

P1

=~ Pannsylvanian C 2 s -2 Mississippian

C1 D3

o

N 0

D2 Devonian

(0 EL

D1

Silurian

Ordovician

Rhaetian

W

Norian Camian Ladinian

-k -k ~k

Anisian Scythian Lopingian

W -k ?9

27 235 241 245

13 9 5 8 8 12 10 17 13

Pragian Lochkovian

25

03

Ashgill Caradoc

02

(Llandeilo) Llanvim

"k -k

Merioneth

"C2

St David's Toyonian Botomian

Sinian

Sturtian Karatau Riphean

2 11

428 443

15 6 9

458 ~t

6 6

47O 495

15 ~

10

~,

23 518 "k

Atdabanian Tommotian Nemakit Daldyn k9 Ediacaran

4 3

525

L 534

,

9

545 21 590

Varangian

o* [ -610 -800

, ^

I 1050

Yurmatin Burzyan

[ ~

i

Neoproterozoic

10 190 --

1000 Mesoptz

1650 2200

~

2450

~

2800

-?- - -

,

1350

Animikean Huronian Randian Swazian Isuan

14

?--k--

Arenig

-C~

14

417

Tremadoc

Vendian

5

.k I "k 290 "k .k 303 Moscovian -k Bashkidan -k 323 Serpukhovian "k Visean "k Tournaisian -k 363 Famennian -k Frasnian "k 377 Givetian Eifelian ~, 391 Emsian -k

Wenlock Llandovery

s

6 4

Sakmadan Asselian Gzelian Kasimovian

S2 S1

Cambrian

1 t

6 13

Pridoli Ludlow

O1

2O8

Guadelupian -k , Kungurian W L! 256

S4 S3

Ma

3.5 18.3

J1 i Sinemurian

2500 Ma Neoarchean

Paleoarchean

0.01 1.63

35.5 t 56.5 65

Aalenian Toarcian -k Pliensbachian

Siderian

Eoarchean ...?...

Aptian Barremian Neocomian "rithonian

-Myr

23.5

Oligocene Eocene Gulf Albian

-Ma 0.01 1.64 5.2

Pliocene Miocene

Callovian Bathonian

(J

Orosirian Paleoproterozoie

Ct

Paleocene

1200 Ma Mesoproterozoie

Holocene Pleistocene

o

850Ma

Chronometric standard

Estimated calibration

Chronostratic standard

545 Ma

1600 Paleoptz 2500

Archean

3500 oonn

Fig. 3.7. Provisional time scale used in this book, the asterisks mark Svalbard strata with fossil record. Compiled from Harland, Armstrong, Cox, Craig, A. G. & D. G. Smith (1990) and modified from Tucker & McKerrow (1995) for Cambrian through Devonian numerical values.

SVALBARD'S GEOLOGICAL F R A M E ( F o r t e y e t al. 1995, b u t c o u n t e r e d by Basset & O w e n s 1996). A n o t h e r p r o b l e m is the status o f the latest P e r m i a n L o p i n g i a n division ( C h a p t e r s 17 a n d 18). N e w scales a p p e a r frequently, b u t are n o t i n t e g r a t e d into this w o r k (Shell 1995; G r a d s t e i n & O g g 1996).

3.2.3

Svalbard's chronometric record

A p p a r e n t n u m e r i c a l ages f r o m isotopic d e t e r m i n a t i o n s o f S v a l b a r d rocks are i n d i c a t e d against a c h r o n o m e t r i c scale (Fig. 3.8). Particular d e t e r m i n a t i o n s will be discussed in their historical c o n t e x t in P a r t 3 w h e r e they are critical (with their sources referenced). This p l o t s h o w s the range o f m o s t p u b l i s h e d results. Analytical a n d o t h e r critical d a t a are n o t r e c o r d e d here because in this general w o r k precise values are n o t relevant for the s t r a t i g r a p h y . T h e p i c t u r e that e m e r g e s reflects n o t only the available rocks a m e n a b l e to such analysis, b u t also the interest o f the investigators a n d the field a n d l a b o r a t o r y costs o f each d e t e r m i n a t i o n .

3.3

The rock frame

N e a r l y all k n o w l e d g e o f geological history, d e p e n d s o n the evidence p r o v i d e d by existing rock. I n d e e d (possibly differing) interpretations by m a n y w o r k e r s as to age, c o n t e m p o r a r y e n v i r o n m e n t a n d processes, p r e v i o u s l o c a t i o n a n d a t t i t u d e etc. m a y be referred to the s a m e r o c k s as p r i m a r y reference. It is t h e r e f o r e p a r a m o u n t to agree o n h o w all scientists m a y refer to p a r t i c u l a r r o c k in c o n v e n i e n t n a m e d r o c k units. F r o m the n a m e d units as listed, for e x a m p l e in section 3.4 a n d in t h e glossary a n d index in P a r t 4 it is e v i d e n t t h a t in even a small area such as S v a l b a r d the geologic c o m p l e x i t y is such t h a t s o m e h u n d r e d s o f units n e e d n a m e s . For many years, especially in the Old World, rocks were described as though their ages were known, or should be known, and this often depended on their contained fossils. The earlier descriptions in Svalbard focused on the fossil horizons, or niveaux, selected from the body of rock in which they occur. Nowadays the whole rock bodies are described. Hence a lithic (approximately, lithostratigraphic) code has developed, largely based on the early American codes. The trend is towards international standardization even for national surveys. This process is not yet complete. For example what is often taken as an international standard (Hedberg 1976) claims only to be a guide in which all contrary opinions expressed on controversial matters by the Subcommission were not referred (Harland 1977). So there is still some way to go. Having been party to other attempts at an international code (e.g. George et al. 1969; Harland et al. 1972) the principles adopted here and throughout this volume interpret the international consensus on matters which have hardly proved to be controversial. T h e r e l a t i o n s h i p b e t w e e n the r o c k (a) a n d the t w o time scales (b) a n d (c) is d e p i c t e d as follows. T h e r e is n o w a y t h a t (b) a n d (c) c a n be related except t h r o u g h (a). A n y o t h e r i n t e r p r e t a t i o n (x) m u s t also derive f r o m (a). Thus: (b)+-+(a)~(c) a n d ( a ) ~ ( x )

3.3.1

A lithic code

This section discusses a lithic c o d e - t o w a r d s an i n t e r n a t i o n a l c o d e for defining, n a m i n g a n d classifying local r o c k bodies or units. T h e c o n s i d e r a t i o n s are r e c o u n t e d n o t as a legal f i ' a m e w o r k c o m p e t i t i v e w i t h o t h e r codes, b u t r a t h e r to indicate t h o s e m a t t e r s w h e r e differences o f o p i n i o n or practice h a v e persisted a n d hence w h e r e this w o r k has m a d e choices a n d i n d e e d r e c o m m e n d a t i o n s . T o this e n d s o m e principles b e h i n d these choices are listed below. (a) The term litbic is used advisedly in preference to lithostratigraphic because in many minds the category 'lithostratigraphic' implies perhaps indefinite parallel systems of other units (biostratigraphic, magnetostratigraphic, chronostratigraphic etc.). The case here is that one neutral scheme only of rock units is necessary, indeed obligatory, and that all other geoscientific disciplines with their terminologies serve to qualify these lithic units in many different ways as in the above formula.

29

(b) The units should be capable of location in the field as mappable units and therefore recognisable to other workers. (c) The rock so classified should not be genetically based. Thus interpretation as to environment of formation (e.g. sedimentary, metamorphic, igneous) must not preclude any rock unit from the lithic code. (d) The units should be conterminous as in a map or section so that there is no overlap or gap between them. Consequently any observation could be related in space to a position in one unit itself identifiable geographically and in relation to other units. (e) Formal definition of a unit begins in some locality, large or small, with thickness and description of the boundary with adjacent units. Features that are convenient may be used to define and characterise a unit and distinguish it from adjacent units. Typically these are lithological (sandstone, limestone, basalt etc.) colour, resistance to denudation, obvious macrofossils, minerals, or geophysical parameters especially if the unit is not exposed or sampled. (f) The time-honoured principle of naming the unit from a local place name is appropriate. Once this has been done, unless there has been a radical weakness in the description, that name should remain attached to the package of rock originally intended whether or not it changes rank up or down from the primary formation. To allow the lithic system to be comprehensive, additional terms such as complex, suite, pluton, sheet may be useful and further division may be necessary by qualifiers (supergroup, subgroup). (g) In naming units or selecting named units some sympathy with those having used a name might well take some precedence over the absolute correctness of application of the geographical name. Brevity and ease of use in other languages are considerations. Nor should the temptation to 'correct' an established name be entertained. Thus the name should also be fixed from its first use and not changed with subsequent political, linguistic, genetic, chronostratic arguments or superior scientific knowledge. The name should thus not be translated or modified in another language other than by transliteration to a different alphabet. Thus once the name of a unit has been published with sufficient description to identify it that name shall have priority. Subsequent fuller descriptions, genetic interpretations, and minor modifications do not qualify to rename the unit. (h) Unpublished names in reports, dissertations etc. when significant work has been done should be used by later workers when publishing the work with formal names and then attached to the originally intended unit of rock as far as practicable, but the date of the unpublished work gives no priority. (i) The formation is the primary unit. A group can only be established from a combination of two or more formations from which it is defined. A member can only be a division of a formation. But greater knowledge may require more divisions which will probably enter at a lower rank and thus the rank of the superior units may be raised. The reverse process is also possible. (j) Hierarchy of named units is a convenient convention. Formations may be grouped in groups, supergroups or subgroups or divided into members or beds in which the division need not be exhaustive. One advantage of hierarchies of names is that each scientist may choose or discover at what level memory serves for the task in hand. (k) Formational boundaries may be expected to be diachronous, whether or not this can be demonstrated, and thus attempts to revise a lithic system to fit time intervals should be resisted not least because time correlation is a matter of changeable opinion. (1) On the other hand if two parts of a formation are shown to have widely discrepant ages it may be suspected that the body could not once have been contiguous so that an additional named unit may be necessary for that part not in the primary definition. In this case the original name should remain with the rock originally or significantly applied. (m) Multiplication of names in any discipline is unpopular and the limitations of memory are often quoted in favour of fewer items. There is a scientific principle in favour of splitting rather than lumping, at least in the first stages of description. That is because if later the splitting proves to have been mistaken then combination of entities is easily applied retrospectively. The other way round, at a later stage to split a lump, may require that the lump then needs redescription by characters not evident in the earlier literature. (n) Disuse of names may be recommended in favour of some better scheme. But names cannot be suppressed except within an organization. Falling into disuse is a more equitable fate. (o) Conversely the use of new names or schemes cannot be obligatory except within an organization. They are essentially recommendations whose use may depend on their perceived scientific merit.

30

CHAPTER

Ma

WJST

WJNT

NDKT

O2LT

BHFT Richarddalen

WNWT I (4) 325 ( ~

NFWT

NFET

NAET t

CHRONOSTRAT 332

I

Vis

-- 350 -- 360

(11)347

(3) 346 I ~ (3) 351 ~ - - 349

(11)358

(2) 358

-- 370 (1) 375 (1) 379 [1) 380(9) 38( (3) 380 (3) 390 (4) 389 (1) 390 (3) 394

(3) 382

-- 390

(3) 385

i (1) 392 ( ~ (1) 395 ( ~

(1) 397

-- 400 (16) 402

(31) 404

(11) 407 (6) 410

4 1 0

-- 420 -- 430

(6)431 15)433 22)436

-- 440

(3) 409.5 (33)413 ~ (16)413 (10) 414 ~_) (15) 420 (33) 4 2 3 (15)425 }16{ 428 (3) 429 429 (9) 430 (15)433 (~) (16)437 (1) 439 (4) 438.5 (3) 443

(16) 410 ' (16) 418 (16) 420 (16) 423 (16) 430 (1)433 (16) 443

(32) ?

- - 377 (2) 381 Giv (3) 385 (~) Eif (2) 387 - -

(2) 396

Ems

(1)413 ( ~

Pra

(27) 4 2 4 (4) 427 (4) 430 (4)434

4) 422 1)425 (1)426 ( ~ (4) 428.4 (32) 432 (~)

(2) 411 (2) 415 (4) 419.3

Lok

417pr i Lud Wen -

(4) 442.6

(34) 442

4 4 3 - Ash

- -

Crd 458 LIo

(16) 455

- -

(33) 461

(11)462 (17) 4 6 6

-- 470

(11) 481

02

Tin

- - 470

(11) 472

-- 480

S Lly

-- 450 -- 460

D2

3 9 1

_

(25) 410 (28)

141442444

(4) 390 (3) 395 (4) 398 (3) 4O0 (3) 405

(24) 4 7 6 (6) 479 (6) 484

Arg

(16) 481

O1

- -

Tre

-- 490

-- 495 -- 500 --

D3

Frs

(5) 376

!

O1

Tou

(3)361 ( ~ - - 3 6 2 . 5 ~ - - - (3)366 ( ~ - - 3 6 7 ram

(3) 370.5

-- 380

- -

NAWT

"]'ADLT 1 1(4) 3151

(11)337

-- 340

3

(16)500 (16)504

(29) 500

-

Mer

-'~3

5 1 0

StD -- 520

-'~2

--518 -

(12)520

-

- - 525 -- 530

Atd

-- 534 (1) 538 (16) 542

- - 540

Tom Man

-- 545 (4) 549

--550 i (33).56.1

555.55-'(4)565 --600 (4)594 -

(2) 556 (14)620 (14)661

(6) 631

"~ 1

(13)600

(23) 624

-

Edi

V2

-- 580 ~ 610

V,

-

(34)677

--700 ~

Stu (8) 766

(4) 789.5 (4) 822.5

--800

- -

8 0 0 -

z

--900

(33) 952 - - 1 0 0 0 - - - -(34) o (22) "~ (22) - - 1 2 0 0 ~ (34)

1100 1130 1135 1200

Kar

(25) 939 14) 955 14) 965

(33) 1050 (36) 1190"

/",11399 1435

-- 1400 i

(35) 1317"

- - 1 0 5 0 ~ Yur

(35) 1735 (28) 1737 ( ~ (18)

--1800 o

(4) 1937

R2

(7) 1275 - - 1 3 5 0 Bur

-- 1600--

R 3

970

R1

--1650--

1750

(31) 1766 (19) 1800

--2000

Animikean

(24) 2121 - - 2 2 0 0 ~ (34) 2200 - - 2400

--2200-Huronian

(20) 2400 -

(23) 2415

(20) 25o0

--2600

Randian

- - 2800

- -

3000~ <

- - 2 4 5 0 - -

- - 2 8 0 0 - (14) 3234 Swazian

--3200

SVALBARD'S GEOLOGICAL FRAME

3.3.2

Some practical stratigraphic conventions in this work

(a) Order of treatment. The primary source of data is the rock as it exists today. When it may be useful to distinguish observation from interpretation, the rock succession, especially if stratified, is described from the top down. This orders the observations as they are seen in the field, drawn in a section, tabulated, or taken from a well log. Descriptive prose may then merge into notes or tables. The order thus stands independently of where descriptive divisions happen to fall. This is applied in Part 2 (Chapters 4-11). However, for interpretation as to age, environment, province etc. the order is in time sequence as is applied in the historical Chapters 12-22. (b) Selection and simplification. Because of the thousands of descriptions of successions, often several for the same locality, the reader needing detailed information must go back to original sources. The key publications are generally cited. Here will be found only generalized sections described in tabular form rather than illustrated in sedimentary logs. (c) Lithic character. The dominant lithic character of a named unit is not a necessary part of its formal name, but is often as useful as the name for recognition in the literature. However, it adds to the wording and so may be included in parenthesis, or excluded for brevity; a consistent policy has not been practicable to adopt. Most lithological terms are commonly understood. Dolostone is preferred to dolomite for the rock rather than the mineral. Feldspathite has been used in the special sense of a rock with > 5 0 % feldspar to avoid implications as to the origin of rocks commonly referred to as gneiss. Palaeosome is the older element in a composite rock (e.g. migmatite) and protolith is the original rock from which a metamorphic rock was formed. (d) Stratigraphic lexicons. Perhaps most importantly, during the preparation o f this work the Committee on the Stratigraphy of Svalbard (SKS) from 1990 has been following such principles as indicated above to agree a list o f names with definitions. The scheme of names in this work has been adjusted to be consistent with the resulting recommendations so far as they have been decided. Happily few changes in this work have been necessary. The positive results of that exercise are indicated in the glossary and index of stratigraphic names in Part 4 by adding an asterisk to those names recommended by SKS. So far, however, those names include only units younger than Devonian. A more comprehensive yet incomplete list had been compiled by Gramberg, Krasil'shchikov & Semevskiy (1990) and this was translated as Norsk Polarinstitutt Report No. 74 in 1991 (Daltmann & M a r k 1991). This is a glossary or lexicon offering alternative names without preference and generally with useful information. Different rank or status of the same unit were often given separate

31

entries; with the exception of these alternatives the names are marked in the list in Part 4 by a dagger Cf)- A much earlier glossary of stratigraphic names in the literature was compiled by Major, Harland & Strand (1956) for the Lexique Stratigraphique International and the glossary was continued privately and formed the basis of the names listed in Part 4. (e) Where differences of opinion cloud the literature as to classification and nomenclature of rock units the principal justification leading to the favoured scheme should appear in an early section in the historical chapters, which scheme may be applied elsewhere in the volume without comment. Unless otherwise explained the latest name should have been applied even to rock units once named differently. (f) There is some confusion about palaeontology. It follows from the above (3.3.1) that palaeontological studies should neither lead to an alternative hierarchy of biostratigraphic units (as implied by some e.g. Hedberg 1976, pp.45-65, Nesten 1989 p. 30 and countered by Harland e.g. 1992) nor to the disqualification of lithic units if recognized in part by fossils. Palaeontology, like any scientific discipline, is liable to diverse applications (not least for biozones in chronostratigraphy), to new discoveries and to new interpretations. No more than sedimentology could it provide the basis for a stable system of lithic units.

3.4

Tectono-stratigraphic terranes and their sequences

This section attempts a comprehensive list of the principal lithic units and tectonic events in terranes that are distinguished for descriptive convenience. In this work the term terrane is used both in its original sense for 'a series, system or group of r o c k s ' . . . [of a region] (Oxford English Dictionary 1971) and for terranes that are also postulated to be allochthonous, or suspected to be so. Thus the terranes listed in this section are purely descriptive without palinspastic implication. In the following section (3.5) the same terranes are considered in combination as relatively far-travelled entities. There need be no confusion in general when the term is qualified e.g. basement terrane, metamorphic terrane, Jurassic terrane, exotic terrane, allochthonous terrane, or suspect terrane. Doren (1990) discussed the terminology arising from the terranological bandwagon. Earlier schematic plans for Svalbard geology may be mentioned. Notably Holtedahl's (1925) comparison of the structure of Britain and Spitsbergen in a prophetic map. Another quite different schematic representation by Sokolov et al. (e.g. 1973) typifies the traditional Russian approach.

Fig. 3.8. Svalbard chronometric record. Numerical age determinations plotted against three linear scales that change at 555.55 and 1000 Ma on the left, and on the right is the chronostratic calibration as used in this volume and given in Fig. 3.7. The eleven columns refer to the descriptive terranes as used in this work and as shown on the diagrammatic map (Fig. 3.9). Some of the earlier results are shown as individual determinations becaue of their wide scatter. Some later work with smaller errors are consolidated as in the original publication. These are relatively reliable and are printed in large digits. In consequence the number of entries plotted is not particularly significant. Indeed the plot is to indicate the data available. Interpretation is discussed in appropriate chapters. Therefore localities, errors, minerals analysed and analytic data with the necessary qualification are not copied from the source and only the isotopic methods are added to the list of references below. The references are given fully with all authors cited because the reference to each number is for the determinations rather than the interpretations. The numbers in brackets refer to the sources for the values given: (1) Hamilton, Harland & Miller (1962), Rb-Sr & K-Ar; (2) Hamilton & Sandford (1964), Rb-Sr; (3) Krasil'shchikov, Krylov & Aljapyshev (1964), K-Ar; (4) Gayer, Gee, Harland, Miller, Spall, Wallis & Winsnes (1966), compilation map and new K-Ar data; (5) Krasil'shchikov (1970), K-Ar; (6) Horsfield (1972), K-Ar; (7) Edwards & Taylor (1976), Rb-Sr; (8) Goroshov, Krasil'shchikov, Met'nikov & Varasavskaya (1977), Rb-Sr; (9) Ravich (1979), K-Ar; (10) HjeUe (1979), Rb-Sr; (11) Hauser (1982), K-Ar; (12) Ohta (1982b), Rb-Sr; (13) Lauritzen & Ohta (1984), Rb-Sr; (14) Peucat, Ohta, Gee & Bernard-Griffiths (1989), U-Pb, K-Ar, Sm-Nd; (15) Dallmeyer (1989), 4~ 39Ar; (16) Daltmeyer, Peucat & Ohta (1990), 4~ 39Ar; Rb-Sr; (17) Dallmeyer, Peucat, Hirajima & Ohta (1990), 4~ 39Ar; Rb-Sr; (18) Gee, Schouenborg, Peucat, Abakumov, Krasil'shchikov & Tebenkov (1992), U-Pb zircon; (19) Gavrilenko & Kamenskiy (1992); (20) Balashov, Fedetov, Skufkin, Sharkov, Kravchenko, Sherstobitova & Ul'yanenko (1992), Rb-Sr (in Russian); (21) Peucat, Dallmeyer & Tebenkov, in Ohta (1992), U-Pb zircon; (22) Ohta (1992), compilation and map; (23) Balashov, Larionov, Gannibat, Sirotkin, Tebenkov, Ryiingenen & Ohta (1993), U-Pb zircon; (24) Bernard-Griffiths, Peucat & Ohta (1993), U-Pb, Sm-Nd & REE; (25) Johansson (1994), U-Pb zircon; (26) Johansson, Gee & Larionov (1995), U-Pb zircon; (27) Gee & Page (1994), 4~ (28) Johansson, Gee, Bjrrklund & Witt-Nilsson (1995), U-Pb zircon; (29) Gee, Johansson, Ohta, Tebenkov, Krasil'shchikov, Balashov, Larionov, Gannibal & Ryungenen (1995), U-Pb zircon, Rb-Sr; (30) Balashov, Teben'kov, Ohta, Larionov, Sirotkin, Gannibal & Ryungenen (1995), U-pb zircon; (31) Larionov, Johansson, Tebenkov & Sirotkin (1995), U-Pb zircon; (32) Tebenkov, Ohta, Balashov & Sirotkin (1996); Rb-Sr; (33) Balashov, Peucat, Teben'kov, Ohta, Larionov & Sirotkin (1966), Rb-Sr & zircon; (34) Balashov, Peucat, Teben'kov, Ohta, Larionov, Sirotkin & Bjornerud (1996) Rb-Sr, U-Pb zircon; (35) Hellman, Gee, Johansson & Witt-Nilsson (1997), zircon Pb-evaporation*. (36) Gee & Hetlman (1996), zircon Pb-evaporation*; (numbers 35 and 36) refers to minimum age of detrital zircon--maximum age of metasediments.

32 3.4.1

CHAPTER 3 the Liefdefjorden Supergroup, which may contain Silurian rocks, and excludes latest Devonian strata that belong to the cover sequence.

The terranes and their sequences

The terranes are listed in two parts: pre-Carboniferous and postDevonian.

basement sequences. In this sense terranes are shown on the Fig. 3.9

The reason is that the post-Devonian strata, while varying in different areas, nevertheless form a coherent sequence that can easily be correlated, and is only significantly interrupted by Paleogene tectonism. It is referred to as the 'cover sequence'. On the other hand, the pre-Carboniferous rocks are often difficult to correlate and have been given quite different nomenclatures in different terranes. This is contrary to some usage in which basement commonly refers to the more highly tectonized pre-Devonian rocks. In that case the Devonian rocks are neither basement nor cover, forming during the later Caledonian movements. At the same time Devonian is used loosely for

with acronyms, a shorthand used in tables and maps in this work. The tectonic significance, if any, of these terranes will be discussed in the following Section 3.5. To complete this list for convenient stratigraphic reference the cover sequences are divided into four main terranes: the Eastern Platform, the Spitsbergen Basin, the Graben, and Bjornoya. The subterrane sequences are listed. To keep the list within manageable bounds, divisions of rank lower than formations are omitted as are supergroup names of the cover sequence. The latter are as follows: Van Mijenfjorden Group (Paleogene) Nordenski61d Land Supergroup Adventdalen Group (Jurassic-Cretaceous) Kapp Toscana Group (Triassic-Jurassic) Sassendalen Group (Triassic) Bfinsow Land Supergroup Tempelfjorden Group (Late Permian) Gipsdalen Group (Carboniferous-Permian) Billefjorden Group (Latest Devonian-Carboniferous) Liefde Bay Supergroup Andr6e Land Group (Early to Early-Mid-Devonian) Red Bay Group (Early Devonian) Siktefjellet Group (?Latest Silurian)

Kvitoya

v,

%"

T Z

BFZA'~'~NAWz"

The pre-Carboniferous successions are thus referred to here as

NAET

Nottvedt et al. (1993) gave an overview and correlation of the cover sequence with that beneath the Barents sea. Thicknesses are intended to give some idea of the nature of the successions. Similarly ages are for guidance and not for application. A. EASTERN BASEMENT TERRANES

NORDAUSTLANDET EASTERN TERRANE (NAET) Franklinsundet Gp Djevlaflota Fm Rijpdalen granites etc Kapp Hansteen Gp Svartrabbane Fm Brennevinsfjorden Gp Helvetsflya Fm Duvefjorden Cpx migmatites and protoliths of metasediments including amphibolites = Duvefjorden Complex.

ESP NDKTj

,,~.

ese

'(BEPT)'~

WJNT 0

4

IHoP?

WJST,

rW

B O] P~~BOB

9

T 121"

,

,1~, 124"

, 1

Fig. 3.9. Tectono-stratigraphic terranes of Svalbard as used in this work. Eastern basement terranes: (NAET) Nordaustlandet Eastern Terrane;

(NAWT) Nordaustlandet Western Terrane; (NFET) Ny Friesland (including Olav V Land) Eastern Terrane; (NFWT) Ny Friesland Western Terrane. Central basement terranes: (ADLT) Andr~e Land-Dickson Land Terrane; (BHFT) Biskayerfonna-Holtedahlfonna Terrane; (WNWT) Northwest Spitsbergen Terrane; (HSDT) Hornsund Terrane. Western basement terranes: (PKFT) Prins Karls Forland Terrane; (FSGT) Forlandsundet Graben Terrane; (O2LT) Oscar II Land Terrane; (NDKT) Nordenski61dkysten-Nordenski61d Land Terrane; (WJNT) NW Wedel Jarlsberg Land-North of Torellbreen Terrane; (WJST) SW Wedel Jarlsberg Land-South of Torellbreen Terrane. Southern basement terrane: (BOBT) Bjornoya Basement Terrane. Cover terranes (post-Devonian sequences): (CBT) Central Basin Terrane; (NBT) North Basin Terrane; (WBT) Western Fold Belt/Basin Terrane; (SBT) Southern Basin Terrane; (NAPT) Nordaustlandet Platform Terrane; (OVPT) Olav V Land Platform Terrane; (BEPT) Berentsoya and Edgeoya Platform Terrane; (KKPT) Kong Karls Land Platform Terrane; (HOPT) Hopen Platform Terrane; (BOPT) Bjornoya Platform Terrane; (MSB) Main Spitsbergen Basin; (ESP) Eastern Svalbard Platform.

NORDAUDSTLANDET WESTERN TERRANE (NAWT) Hinlopenstretet Supergp 2.4 km Oslobreen Gp 1 km Sparreneset Fm, carbonates (Ordovician) Krossoya Fm, carbonates, 800 m (Cambrian) Polarisbreen Gp 1.25 km Klackbergbukta Fm, 650 m shales (?Ediacara) Sveanor Fm, 300 m tillite (Late Varanger) Backaberget Fro, 290 m (Early Varanger) Murchison Bay Supergp, 6.5 km Roaldtoppen Gp, 1.25 km Rysso Fm 500 Celsiusberget Gp, 2.1 km Raudstup-Sfilodd Fm, 550 m Norvik Fm, 340 m Flora Fm, 1250m Franklinsundet Gp, 1.8 km Kapp Lord Fm, 1000m Westmanbukta Fm, 625 m Persberget Fm, 150 m Meyerbukta Gp in W; Austfonna Gp in E, 1.3 km Innvikhogda Fm, 400+ m Djevlaflora Fro, 800+ m basal quartzite Fro, 0-100+m Kapp Hansteen Gp, 2000 m Norgekollen Fro, quartz porphyrites, porphyrite Gerardodden Fm, andesites, tholiites, volcanics and intrusives Orogenic episode = Botniahalvoya unconformity

SVALBARD'S GEOLOGICAL FRAME Brennevinsfjorden Gp, 3000 + m arenites and argillites paragneiss and palaeosomes in migmatites and granites (ofmid-Paleozoicage) NY FRIESLAND (INC. OLAV V LAND) EASTERN TERRANE (NFET) (Tournaisian unconformable cover). Late tectonic granite plutons Ny Friesland Orogeny Hinlopenstretet Supergp, 2 km (Cambro-Ord.) Oslobreen Gp, > 1.2 km, carbonate: (Arenig to Early Llanvirn) Valhallfonna Fm, 220 (?Late & Mid-Canadian) Kirtonryggen Fm, 750 m (Early Cambrian) Tokammane Fm, 192m (Vendian) Polarisbreen Gp, 0.7 km (Ediacara) Dracoisen Fm, 245 m (Late Varanger) Wilsonbreen Fm, 160 m (Early Varanger) Elbobreen Fm, 362m Lomfjorden Supergp, 6 km, Akademikerbreen Gp, 2.0 km, all carbonates Backlundtoppen Fm, 360-700 m carbonates Draken Fm, 25-300 m carbonate conglomerate Svanbergfjellet Fm, 100-625 m (Sturtian) Grusdievbreen Fm, 865 m (700-800 Ma) Veteranen Gp, 3.8 km, mainly siliciclastic Oxfordbreen Fro, 550m Glasgowbreen Fm, 540m Kingbreen Fm, 1500m quartzites with limestones (800-900 Ma) Kortbreen Fm, 1200m conformable on Vildadalen Fm NY FRIESLAND, WESTERN TERRANE (NFWT) (Tournaisian unconformable cover) Ny Friesland (Caledonian) Orogeny Stubendorffbreen Supergp, 11 km+ Planetfjella Gp, 4.7 km Vildadalen Fm, 3250m Flgten Fm, 1500m unconformity Harkerbreen Gp, 3.5-4.0 km Sorbreen Fm, 250+ m, psam, qi & amph Vassfaret Fm, 600 m quartzites and amphibolites Bangenhuk Fm, 200 m granitoid Rittervatnet Fm, 350m semipelites, amphs, feldspathites Polhem Fm, 900+ m psammites unconformity Instrumentberget-Fl~ttan granitoid Finnlandveggen Gp, 2.7+ km Smutsbreen Fm, 1200+ m, peliles & marbles Eskolabreen Fm, 1500+ m gneissose feldspathites & amphibolites ?AustJjorden tectonothermal event

(1750 Ma) (<1317Ma) (1750 Ma) (< 1190 Ma) (1750 Ma) (?2415 Ma?)

B. CENTRAL BASEMENT TERRANES ANDRI~E LAND-DICKSON LAND TERRANE (ADLT) (Tournaisian unconformable cover) Svalbardian tectogenesis Liefde Bay Supergp Andr6e Land Gp, c. 6+ km (Frasnian, Mimer Valley Fm, 740 m in South Dickson Land, Givetian & Eifelian) (Givetian) Wijde Bay Fm, 500-600 m (Eifelian) Grey Hoek Fm, 1000m (Emsian, Late Pragian) Wood Bay Fm, 3000 m BISKAYERFONNA-HOLTEDAHLFONNA TERRANE (BHFT) Andr6e Land Gp Wood Bay Fm in south unconformity folding Red Bay Gp, 3.7+ km Ben Nevis Fm, 900 m Fr~enkelryggen Fm, 600-750m Andr6ebreen Fm, 1400m Rivieratoppen Fm, 500-700m

(Early Pragian)

Syn-depositional Haakonian Diastrophism

33

Siktefjellet Gp, c. 3.5 km (?Silurian) Albertbreen (sandstone) Fm, 1400-3050m Lilljeborgfjellet (conglomerate) Fm, 100-400 m Rabotpasset (conglomerate) Fm, ?100 m Siktefjellet and Red Bay Groups rest on unconformity represented by Smeerenburgian (Caledonian) Orogeny Krossfjorden Gp, 6+ km (Proterozoic) Lerneroyane Fm, 1500m mainly marble Biskayerhuken Fm, 3.5+ km, mainly pelites Montblanc Fm, 850-1000m pelites, qtz-amphibolites and gneiss pass laterally down into migmatites containing Smeerenburgian neosomes and minor intrusions Richarddalen Orogeny (970 and ?3234 Ma) Richarddalen Gp (Proterozoic-?Archean) complex of eclogite, mylonitic reworked metagranite, metabasic and ultrabasic rocks, gneiss and marbles WESTERN NORTHWEST TERRANE (WNWT) Andr6e Land Gp (Early Devonian) Wood Bay Formation - S of Kronebreen (Lochkovian) Red Bay Gp Conglomerates in graben N of Kongsfjorden unconformably on Generalfjella Fm (Devonian-Silurian) Hornemantoppen (granite) Batholith in N Smeerenburgian tectonothermal orogeny (Proterozoic) Krossfjorden Gp, 7.5-13 km Generalfjella Fm, 2.5 km, marbles and pelites Signehamna Fm, 2-2.5 km, mainly pelites Nissenfjella Fm, 2-3 km, pelites with amphibolites pass down into Smeerenburgian migmatite complex Kollerbreen Fm, 8-10 km Waggonwaybreen Fm, 3 km containing Smeerenburgian neosomes and intrusions HORNSUND TERRANE (HSDT) (E Wedel Jarlsberg Land, SW Torell Land, and E Sorkapp Land) incl. Gipsdalen Gp (Early Permian-Pennsylvanian) Hyrnefjellet Fm, 270+ m unconformity: Adriabukta Folding Billefjorden Gp (Mississipian) Adriabukta Fm, 300 m unconformably on [Andr~e Land Gp] (Mid-Early Devonian) Marietoppen Fm, 1100m (Emsian-Siegenian) tectonic lower contact Hornsund Supergp Sorkapp Land Gp, 1.4+ km Arkfjellet (lst) Fm, (age?) Hornsundtind (lst) Fm, 480 m (Late Canadian) Negerbreen (lst) Fm, 120 m Dusken (lst) Fm, 100 m ?Unconformity Luciapynten (lst) Fm, 400 m Wiederfjellet (qi) Fm 300 m ?Hornsundian unconformity Sofiekammen Gp, c. 1 km Nordstetinden (dst) Fm, 150 m Gngdberget (marble) Fm, 250-300 m Slaklidalen (lst) Fm, 10-120m Vardepiggen Fm, 130-215 m (Late Early Cambrian) Bfftstertoppen (dst) Fm, 100-150m ?Jarlsbergian unconformity [Sofiebogen Gp], c. 4.4 km (Vendian) G~shamna in S & Bogstranda in N (phyllite) Fm, 2.5-3.0 km, (Vendian) ?Ediacara Fannytoppen (dst) Fm, 100 m (?Ediacara) Fannypynten (tilloid) Fm, 500 m (Late Varanger) unexposed unit, 300 m Hansvika (tilloid) Fm, 500 m (Early Varanger) tectonic contacts with Gn~lberget (marble) Fm H6ferpynten (dst Fm) 710m (Late Sturtian) ?Orogeny Magnethogda Gp (Proterozoic)

34

CHAPTER 3 C. WESTERN BASEMENT TERRANES

PRINCE KARLS FORLAND TERRANE (PKFT) Grampian Gp, 2.7 km Geddesflya Fro, 1800 m quartz, siltstone, turbidites Fugelhuk Fm, 400 m massive quartzite Barents Fm, 500 m siltstone, slate turbidites Sutorfjella Conglomerate Mbr Conqueror Fm, 850m

(?Silurian)

Tectonic episode

Utnes Fm, 80 m mainly slate Scotia Gp, 1 km Roysha Fm, 400 m dark slate Kaggan Fm, 300 m green & purple slate Baklia Fm, 200-300 m dark slate & carb (Ediacara) (=Black Shale Fm of Knoll & Ohta 1988) Peachflya Gp, 1.3 km Knivodden Fro, 400 m grey & green phyllite Hornnes Fm, 350 m phyllite sandstone and 1st Alasdairhornet Fm, 190m tufts and lava flows Fisherlaguna Fm, 350m dark phyllite Geikie Gp, 0.8 km Rossbukta Fro, 300 m dark phyllite Gordon Fm, 470 m dst, 1st, phyllite Ferrier Gp, 1.1 km Neukpiggen Fm, 300 m Peterbukta Fro, 100m psam. sch. & stones (Late Varanger) Hardiefjellet Fm, 120-500 m psammitic schist & stones (Late Varanger) Isachsen, Fm, 150+ m quartz chlorite schist base not seen tectonic contact

Pinkie Fro, 200+ m metavolcanics

(?Early Varanger)

FORLANDSUNDET GRABEN TERRANE (FSGT) Buchananisen Gp, c. 6 km Balanuspynten Fm, 1650+ m Aberdeenflya Fm, 2800+ m McVitiepynten Subgp Marchaislaguna Fm, 55-600+ m Krokodillen Fm, 400+ m Reinhardpynten Fm, 210+ m Sesshogda Fm, 120+m Selvgtgen Fm, 40-170 m

(Late Paleogene)

OSCAR II LAND TERRANE (OIILT) Billefjorden Gp, c. 0.5 km Vegard Fm, 30-360 Orustdalen Fm, c. 100 m

(Mississipean)

Unconformity

Bullbreen Gp ?Sarsoyra Fm, 450 m Holmesletfjella Fm, 150+ m Bulltinden Fm, 60 m Motalafjella Fm, 260 m

(?Silurian) (Early-mid Silurian) (Mid Late Ordovician)

unconformity = Eidembreen tectogenesis

Vestg6tabreen Complex tectonic contact

Comfortlessbreen Gp, c. 6 km Aavatsmarkbreen Fm, I km, phyllite Annabreen Fro, 2 kin, quartzite Haaken Fm, 2~3 km, tillite conformable contact St Jonsfjorden Gp, c. 4 km Alkhorn Fm, 1 km Lovliebreen Fm, 1 km, Moefjellet Fm, 500-800 m Trondheimfjella Fm, 1300 m

(Vendian) (?Ediacara) (Late Varanger)

(Early (Early (?Early (Early

Varanger) Varanger) Varanger) Varanger)

NORDENSKIOLDKYSTEN (NORDENSKIOLD LAND) TERRANE (NDKT) Kapp Linn6 Fm, 2.5+ km, granitoid tiUite (Late Linn~fjella unit, 2+ km, ph.qi & 1st Malmberget unit, 1st marbles, semi-pelites, qi (Early Lhgnesbukta Gp, ?3+ km (Early Lgtgneset Fm, schistose tillite, 350-450 m, Gravsjoen unit various metasediments & basites Lgtgnesrabbane Fm, 1-2km, (Early Kapp Martin Fm, 800 m, cgls & phyllite

Varanger) Varanger)

Varanger)

NW WEDEL JARLSBERG LAND (NORTH OF TORELLBREEN) TERRANE (WJNT) (Late Varanger) Kapp Lyell Gp, 3 km, (Late Varanger) Lyellstranda Fm, 1.3 km, Logna Fm, 0.2km, phyltite (Late Varanger) Dundrabeisen Fm, 1.4km, Konglomeratfjellet Gp----(Early Varanger) Dunderdalen Fm in W phyllites & minor olistoliths = Chamberlindalen Fm, 2 km, in E phyllite & basic volcanics Slettfjelldalen Fro, in W = Solhogda Fm, in E Floykalven Fm, in W 0.5 kin, diamictite = Gaimardtoppen Fm, in E 0.7 km, cgl, sst, 1st Thiisfjellet Fm, 0-100m black pyritic 1st 0-100 m in E local basal cgls 0-50 m in W unconformable base seen in W resting on Torellian Orogeny

(pre-Vendian)

Nordbukta Gp, c. 4 km Dordalen Fm, 150+ m banded dst, 1st marble Thiisdalen Fm, 200 m dark phyllite Trinutane Fm, 380m Seljehangfjellet Fm 700 m sandy dst Botnedalen Fm, 300 m play 1st, dst & phyllite Peder Kokkfjellet Fm, 60 m sandy dst Evafjellet Fm, I km, qi & phyllite Kapp Berg Fm, 1+ km, ph + qi

SOUTHWEST-WEDEL JARLSBERG LAND (SOUTH OF TORRELLBREEN) TERRANE (WJST) (modified from Birkenmajer 1993, Czerny et al. 1993, Harland et al. 1993) (Early Varanger) Aust Torellbreen Gp Slyngfjellet Fm Deilegga Subgp 3.5 km Bergskardet Fm 500+ m Bergnova Fm 1800 m Tonedalen Fm 1200+ m Vimsodden Subgp, 2 km Jens Erikfjellet Fm l l00m Elveflya Fm 900 m Tectonothermal event c. 950 Eimfjellet Gp (Czerny et al. 1993), 4+ km Pyttholmen Fm [Nottinghambukta Fm] 1550 m (Mesoproterozoic) Gulliksenfjellet Fm, 500-850 m Bratteggdalen Fm Steinsvikskardet 100~50 m Sk~lfjellet Fm, 950-1400 m (Mesoproterozoic) Eimfjellbreane Fm Skjerstranda Fm Isbjornhamna Gp, 2850+ m (Mesoproterozoic) Revdalen Fm, 250-350 m Ariekammen Fm, 1500+ m Skoddefjellet Fm, 1000+ m Tectonic contact

Dunoyane Fm, 750m D. SOUTHERN BASEMENT TERRANE

?concordant contacts

Kongsvegen Gp Mtillerneset, 2 km, semi-pelite, south of St Jonsfjorden North of Engelskbukta are Bogegg Fm, 1.5 km, semi-pelites with dol-qi. Steenfjellet, Fm 0.1 km, marbles, N of Engelsbukta Nielsenfjellet Fm, 2.5 km, schistose, base not seen

Varanger)

(Late Sturtian)

BJORNOYA BASEMENT TERRANE (BOBT) Caledonian tectogenesis

Ymerdalen Gp, c. 0.65 km Antarcticfjellet Fm, 240+ m Perleporten Fm, 400+ m unconformity

(Canadian) (Early Caradoc)

SVALBARD'S GEOLOGICAL FRAME Bjornoya Gp, c. 0.6+ km Sorhamna Fm, 175+ m Russhamna Fm, 400+ m [part of Barents sea] E. COVER TERRANES (post-Devonian sequences) CENTRAL BASIN TERRANE (CBT) Van Mijenfjorden Gp, 1.5-2.5 km Aspelintoppen Fro. 1000+ m (CB6) Battfjellet Fro, 60-300 m (CB5) Frysjaodden Fro, 200-400 m (CB4) Grumantbyen Fm, 45-200 m (CB3) Basilika Fro, 10 350m (CB2) Firkanten Fro, 100-170m (CB1) Adventdalen Gp, c. 2 km Carolinefjellet Fro, 270-1214+ m Helvetiafjellet Fro, 53-100 m Janusfjellet Subgp Rurikfjellet Fm, 176-342 m Agardhbukta Fm, 243 m Kapp Toscana Gp, 253 m Wilhelmoya Fm, 1-50 m De Geerdalen Fm, 190 m Tschermakfjellet Fm, 63 m Sassendalen Gp, 725 m Botneheia Fm, 157 m Sticky Keep Fm, 230 m Vardebukta Fm, 254 m Tempelfjorden Gp Kapp Starostin Fm etc. below surface

(late Varanger, Vendian) (earliest Vendian)

(Paleogene) (Eocene)

(Paleocene)

(Early Cretaceous)

(Rhaetian) (?Norian) (Triassic)

(Permian)

NORTH BASIN TERRANE (NBT) Sassendalen Gp, 316m (Triassic) Botneheia Fm, 100 m Sticky Keep Fm, 130 m Vardebukta Fm, 86 m Tempelfjorden Gp, 381 m (Permian) Kapp Starostin Fm, 381 m Gipsdalen Gp, 850 m (Permian-Pennsylvanian) Dickson Land Subgp Gipshuken Fm, 211 m Wordiekammen Fm, 180 m Campbellryggen Subgp (Pennsylvanian) Minkinfjellet Fm, 156 m Ebbadalen Fm, 281 m Hultberget Fm Billefjorden Gp (Mississippian) Mumien Fro, 127 m H~rbyebreen Fm, 189 m resting unconformably on (Svalbardian deformed rocks) Andr6e Land Group in W and Stubendorffbreen Supergp in E WESTERN (FOLD BELT) BASIN TERRANE (WBT) (NORTHERN) Van Mijenfjorden Op (Paleocene) Ny-Alesund Subgroup, 240 m Broggerbreen Fm, 120+ m Kongsfjorden Fm, 120 m Sassendalen Gp (Early Triassic) Vardebukta Fm, 0-50 m Tempelfjorden Op (Late Permian) Kapp Starostin Fm, 1200m Oipsdalen Gp (Early Permian-Pennsylvanian) Dickson Land Subgp Gipshuken Fro, 88-146 m Wordiekammen Fm, 160-290 m Morebreen Mbr, 130m Charlesbreen Subgp (Pennsylvanian) Scheteligfjellet Fm, 153 m Br;~ggertinden Fm, 360 m Billefjorden Gp. (Mississippian) Vegardfjella Fro, 30 m Orustdalen Fm, c. 100 m resting unconformably on Kongsvegen Gp and Comjortlessbreen Gp

35

WESTERN (FOLD BELT) BASIN TERRANE (WBT) (CENTRAL) Van Mijenfjorden Gp (Paleogene) Firkanten Fm, 100+ m Adventdalen Gp, c. 1 km E. Cret.-L. and M. Jurassic) Carolinefjellet Fm, 180 m Helvetiafjellet Fm, 150 m Janusfjellet Subgp, 710 m Rurikfjellet Fm, 400m (Early Cretaceous) Agardhfjellet Fm, 310 m (Late and Mid-Jurassic) Kapp Toscana Gp, 330m (Late Triassic) Wilhelmoya Fm, 30 m De Geerdalen Fm, 300 m [Tschermakfjellet Fm, 0 m?] Sassendalen Gp, 1.4 km (Mid- and Early Triassic) Botneheia Fm, 400 m (Middle Triassic) Sticky Keep Fm, 400 m (Early Triassic) Vardebukta Fm, 600m Tempelfjorden Gp, 500 m Kapp Starostin Fm, 500m (Permian) Gipsdalen Gp Dickson Land Subgp, 400-600 m (Early Permian Late Permian) Gipshuken Fm Workiekammen Fm Charlesbreen Subgp, c. 600 m (Early Pennsylvanian) TSrnkanten Fm, 251 m Petrellskaret Fm, 350 m Billefjorden Gp, 1.1 km (Mississippian) Vegardfjella Fm, 358 m Orustdalen Fm, 759 m resting unconformably on basement SOUTHERN BASIN TERRANE (SBT) Kapp Toscana Gp (Late-Mid-Triassic) Wilhelmoya Fm, 60 m De Geerdalen Fm, 31 m Tschermakfjellet Fm, 16 m Sassendalen Gp (Mid-Early Triassic) Botneheia Fm, 60 m Sticky Keep Fm, 90 m Vardebukta Fm, 60 m Tempelfjorden Gp (Late Permian) Tokrossoya Fm, 300+ m Gipsdalen Gp (Early Permia~Pennsylvanian) Treskelen Subgp Treskelodden Fm, 170 m Hyrnefjellet Fm, 270 m Billefjorden Gp (Mississippian) Sergeifjellet Fm, 260 m Hornesundneset Fm, 720 m Adriabukta Fm, 300m NORDAUSTLANDET PLATFORM TERRANE (NAPT) Kapp Toscana Gp (Late Triassic) De Geerdalen Fm, 50+ m Sassendalen Gp (Mid- and Early Triassic) Barentsoya Fm, 118 m Tempelfjorden Gp (Permian) Kapp Starostin Fm, 91 m Gipsdalen Gp (Early Permian-Late Pennsylvanian) Dickson Land Subgp Gipshuken Fm (Sorfonna Mbr and Zeipelodden Mbr), 121 m Wordiekammen Fm (Idunfjellet Mbr), 150 m Harbardbreen Fm, 15-50 m OLAV V LAND (& WILHELMOYA) PLATFORM TERRANE (OVPT) Janusfjellet Subgp Agardhfjellet Fm, 50+ m (Late and Mid-Jurassic) Kapp Toscana Gp (Late Triassic) Wilhelmoya Fm, 119 m De Geerdalen Fro, 254m Tschermakfjellet Fm, ?34+ m Sassendalen Gp (Mid-Early Triassic) Barentsoya Fro, ?

36

CHAPTER 3

Tempelfjorden Gp Kapp Starostin Fro, 140+ m Gipsdalen Gp Dickson Land Subgp Gipshuken Fm, 140-179m Wordiekammen Fm, 170 m Maltebrunfjellet Fm, 60-70 m

(Late Permian) (Early Permian-Pennsylvanian)

BARENTSOYA AND EDGEOYA PLATFORM TERRANE (BEPT) Kapp Toscana Gp (Late Triassic) Negerfjellet Fm, 400+ m Edgeoya Fm, 130-165 m Sassendalen Gp (Triassic) Barentsoya Fro, 300 m Tempelfjorden Gp (Late Permian) Kapp Starostin Fm (Kapp Ziehen Mbr), 75+ m (Permian) deep wells: Plurdalen-1 Raddedalen- 1 Kapp Starostin Fm Gipsdalen Gp, c. 430 m (Early Permian Pennsylvanian) Gipshuken Fm Wordiekammen Fm Campellryggen Subgp, c. 1.9 km and ?Billefjorden Gp. (Mississippian) KONG KARLS LAND PLATFORM TERRANE (KKPT) Adventdalen Gp Kong Karls Land Fm, 72 m (Barremian) Kongsoya Fm, 170 m (Hauterivian-Pliensbachian) Kapp Toscana Gp Wilhelmoya Fm (= Svenskoya Fm), 196+ m (?Sinemurian-Rhaetian) HOPEN PLATFORM TERRANE (HOPT) Kapp Toscana Gp (Rhaetian) Wilhelmoya Fm = Lyngefjellet (sandstone) Mbr, 80+ m Flatsalen (shale) Mbr, 55+ m (?Norian) Iversenfjellet Fm, 290+ m = c. De Geerdalen Fm 270+ m deep wells: Hopen-I and Hopen-2 Tchermakfjellet Fm, c. 350 m Sassendalen Gp (Mid Early Triassic) Barentsoya Fm, c. 320 m Tempelfjorden Gp Kapp Starostin Fm, c. 230 m (Early Permian Pennsylvanian) Gipsdalen Gp Gipshuken Fm Wordiekammen Fm, c. 800 m Minkinfjellet Fm Ebbadalen Fm, 500m (Mississippian) Hultberget Fm BJORNOYA PLATFORM TERRANE (BOPT) (Triassic) Sassendalen Gp Skuld Fm, 135m (Late Mid-Triassic) (Mid-Early Triassic) Urd Fm, 65 m (Late Permian) Tempelfjorden Gp Miseryfjellet Fm, 115 m (Permian) group undecided Hambergfjellet Fm, c.100 m (Early Permian-Pennsylvanian) Gipsdalen Gp Kapp Duner Fm, 75 m Kapp Hanna Fm, 150+ m Kapp KSre Fm, 215 m Landnordingsvika Fro, 200 m (Mississippian) Billefjorden Gp Nordkapp Fm, 230 m (part Famennian) Roedvika Fm, 360 m

3.4.2

Combined sequence for Svalbard

From the successions listed above a number of tectonic episodes may be taken separately or listed together. By combining the diastrophic events it does not follow that they all occurred in a single Svalbard sequence, but it does open the mind to possible cot-

relations and connexions both within Svalbard and elsewhere, and it closes the mind to tectonic events elsewhere that appear to have left no mark in Svalbard. An example of such a negative conclusion is that Svalbard appears to show little evidence of the Finnmarkian phase (Early Cambrian) of the Caledonian Orogeny in Scandinavia (Sturt, Pringle & Ramsay 1978), if indeed such a phase is significant in this respect it sides with Greenland west of Iapetus. Archean and early Paleoproterozoic events are recorded in zircons in proto-basement rocks, but there are too few records to generalize. They are discussed in Chapter 12. Leaving these aside the following tectonic or thermal episodes are established. Late Paleoproterozoic igneous rocks systematically dated by zircons around 1750Ma are found in northeastern Svalbard (Ny Friesland and possibly in Nordaustlandet). These events might correspond to the Rinkian of East Greenland. Early Neoproterozoic zircons in volcanic and igneous rocks approximate 950 M a from northeast, north central and southern Svalbard. This widespread evidence suggests a late Grenvillian correlation in Laurentia. Undated diastrophism, certainly pre-Vendian, might correspond to the above or to later tectonic episodes in southwestern Wedel Jarlsberg Land and have been referred to Torellian and Werenskioldian events. Slight, late Vendian or early Cambrian, tectonism (Jarlsbergian) is recorded in the middle Hornsund region. Early to mid-Ordovician tectonism (the Eidembreen phase) is characteristic of central western Spitsbergen and appears to correlate with the M'Clintock orogeny of Pearya in Northern Ellesmere Island. Mid-Silurian time was the climax of a general Silurian tectonism (Ny Friesland Orogeny) in both northeast and northwest Svalbard and corresponds to the main Caledonian orogeny that united Baltica and Laurentia. Latest Silurian and Early Devonian events continued the Caledonian evolution as are evident in northern Svalbard. (a) (b) (c)

Ny Friesland granite emplacement; Smeerenburgian migmatic invasion of northwest Spitsbergen rocks followed by granite emplacement; disturbed sedimentation and tectonism in central north Spitsbergen (Haakonian).

These ?latest Silurian-earliest Devonian events may correlate with events in the Queen Elizabeth Islands (Trettin 1991, p. 337) where late Silurian sinistral transpression accreted Pearya to the Clements Markham, Northern Heiberg and Hazen fold belts. Similar deformation episodes took place in the Boothia and Inglefield uplifts where continued deformation is recorded into Lochkovian and Pragian time. The southern Urals witnessed strong compression about that time (Korinevskiy 1988). (d)

A pre-Wood Bay folding episode has been demonstrated by A. M c C a n n (pers. comm.) but not yet named.

Late Devonian (Svalbardian) tectonism affected much of north Spitsbergen. This Svalbardian episode may be related to Phase 5 and/or Phase 6 of Trettin (1991, p. 338) in the Innuitian Orogen as follows. (5) A Givetian(?)-Frasnian uplift of northwestern Hazen Fold Belt... is tentatively attributed to renewed sinistral strike-slip, and correlated with a second, poorly dated episode of compressional deformation in northern Axel Heiberg Island. (6) Extensive compressive deformation, known as the Ellesmerian Orogeny s e n s u s t r i c t o , occurred throughout the Franklinian mobile belt.., in latest Devonian-Early Carboniferous time .... The rocks deformed by the foregoing events are referred to as basement. The overlying rocks are cover and may be in basin or platform mode. Some would restrict the term basement to pre-Devonian rocks, whether or not Devonian strata with thicknesses up to 8000 m are present, and so match the earlier successions which are variable and often expose more than 8000 m.

SVALBARD'S GEOLOGICAL FRAME However, the cover sequence embraces all of Svalbard in a relatively uniform and coherent succession. It begins with the Billefjorden Group (Late Famennian through Serpukhovian), with minor basin formation associated with the earlier fault zones with sedimentary thicknesses up to 1250 m of grey fluvial/alluvial clastics. The mixed sequence of the Gipsdalen Group (Bashkirian to Artinskian) followed, totalling up to 1800 m. The earlier Subgroup (Campbellryggen) begins with red beds followed by evaporites continuing the separation into fault-bounded basins. This was followed by more extensive carbonates of the Dickson Land subgroup deposited over a more stable platform. That sequence reflected a transition from humid non-marine environments through red clastic and sabkha sedimentation and, with rising sea level, to shallow marine carbonates. The Tempelfjorden Group (up to 460 m Artinskian to Wordian) of silicified marine clastics with some carbonates reflects widespread stable conditions, with marine transgression promoting mature cool deep shelf environments. Minor diastrophism is evident especially in the Carboniferous sequence. It may be regarded as the waning phases of Caledonian tectonism or as a weak correlative of the Variscan movements. Svalbard, in its Arctic context, was remote from Variscan tectonism far to the south but possibly southern Spitsbergen recorded these effects more than further north. Birkenmajer (1994) noted Devonian-Carboniferous, Mississippian-Pennsylvanian and midPermian unconformities. The following three groups of Mesozoic strata continued relatively stable marine platform deposition, but with invasion by advancing deltas. The Sassendalen Group (latest Permian through Ladinian) comprises marine shales, verging on anoxic environments, upwards coarsening into sandstones in several episodes. The Kapp Toscana Group (Ladinian through ToarcianBajocian and little more than 500m thick) is characterized largely by deltaic sandstone incursions from the north and east into a marine environment. The Rhaetian-Liassic story differs in that the main sedimentation occurs in eastern Svalbard while most of Spitsbergen became a positive area recording only thin deposits. The Adventdalen Group is more complex (c. 550 to c. 1700m) beginning in the west with a Bathonian basal conglomerate the Jurassic strata are marine clastics. Around the Jurassic-Cretaceous boundary and well into Neocomian and even Barremian time minor diastrophism, renewing older fault activity, caused local disconformities after which basic igneous intrusion and volcanic activity was widespread especially in the east. The Aptian-Albian phase was one of major deltaic advance. Further south in the Barents sea floor 'Cimmerian' disturbances have been identified, especially by the petroleum industry. Strictly Cimmerian refers to the Tethys, but has been used loosely for almost any Mesozoic unconformity. Late Cretaceous slight tilting up to the north and erosion truncated the upper Adventdalen Group strata making a peneplain for the deposition of the basal conglomerates of the ensuing Van Mijenfjorden Group (Paleocene through Eocene and up to 3000m preserved (and ?2000m lost). Dominantly continental deltaic clastics with Paleocene coals prevailed but with a marine basin developing in central and west Spitsbergen. The West Spitsbergen Orogeny (mainly Eocene) is reflected in its early stages by the main sediment sources coming from new uplift in the west which then dominated the eastern deltaic advance. The orogen forms a belt in the west with thin-skinned thrusting and folding extending eastwards and causing renewed compressional structures along the ancient fault zones in the east. The orogeny was preceded and followed, if not accompanied, by graben formation along the west coast with sediment thicknesses up to more than 5000 m. Thereafter the main sedimentary record is confined to the sea and reflects the uplift and erosion of Svalbard. Quaternary deposits appear as a transient record in the dominantly denudational final chapters.

3.4.3

37

Sequence stratigraphy

The sequences outlined above are tectonically controlled. Sea level changes, of course, have tectonic and climatic origins; but sequences related to eustasy are on a finer scale. These already serve to distinguish some beds and members, but global correlation is generally inadequate to relate such relative changes of sea level to global changes and so to distinguish local diastrophism from the eustatic component. However, there are some notable global effects and these are mentioned elsewhere leaving the detailed discussion to the later chapters. In due course with finer discrimination such changes may aid in correlation; but that is perhaps for later work to accomplish. At present there is little obvious correlation between the sequence stratigraphy and eustatic curves of Shell's (1995) G e o l o g i c a l D a t a T a b l e - M e s o z o i c . In their Paleozoic table major anoxic events are noted (i) for Europe in Early Capitanian time (i.e. ?post-Kapp Starostin Fm) and the Svalbard hiatus may correspond to the southern hemisphere glaciation with reduced sea levels (ii) for Laurussia and N Africa in Late Frasnian time; and for earlier events not easy to relate to the Svalbard record. At a more local level sequence stratigraphy is a new name for current refinements in stratigraphic (sedimentological-tectonic) description.

3.5

Geotectonic interpretation

This section addresses some controversial matters of interpretation. Discussion with evidence will come later. The purpose here is to identify the problems and outline some possible solutions. This gives fair warning to sceptics to look closely at the evidence as it unfolds. It may be worth repeating that in this book, as well as in this chapter, description generally precedes interpretation, so that the information presented is not intended to be structured to favour one viewpoint. However, after discussion, working hypotheses are arrived at that are intended to be consistent throughout the work. The following discussion is against a background in which majority opinion opposed any idea of continental drift until about 1964 after which the Bullard et al. (1965) model, and its successive modifications, to restore the spreading of the Arctic and Antarctic oceans were widely accepted. Thereafter most geologists assumed that Svalbard had remained in its pre-Cenozoic position as an indivisible unit throughout its history and this led to elaborate assumptions about correlation of pre-Devonian successions. The most fixist (as distinct from mobilist) school remained in Russia. A typical interpretation of the structure of Svalbard is seen in that by Sokolov et al. (1973) in which its geological history is interpreted in global evolutionary phases based on Russian experience.

3.5.1

Provinces and allochthonous terranes

Historically Spitsbergen was a key element in some of the earliest speculations of continental drift. One problem was that geometrically by restoring the Spitsbergen and Greenland continental shelves to a pre-Atlantic fit two configurations were possible with Spitsbergen against Central East Greenland, as in Wegener's reconstruction (e.g. 1924, fig. 20/24) or against northern Greenland as in Taylor (1928) and du Toit (1937, p. 169). Although their maps were not precise, when the first detailed fits of the continental shelves were attempted as by Carey (1958, pp. 207-209) who placed Svalbard to the east, and Bullard et al. (1965) who placed it to the north, the ambiguity remained as was illustrated in Harland (1965, figs 1 & 2). The geometrical ambiguity was compounded by competing stratigraphic affinities. Having visited Eastern Greenland with Lauge Koch, after working on the pre-Carboniferous rocks of Ny Friesland, it was confirmed forcibly in my mind (as already

38

CHAPTER 3

indicated by Kulling) that the two sequences were too similar to be an accidental coincidence. This favoured the east Greenland location (e.g. Harland 1959, 1961). However, the work in CSE moved up the stratigraphic column in Svalbard. It then became equally impressive that the cover sequence of Svalbard showed very close affinity with that of the Queen Elisabeth Island sequences in the Canadian Arctic. This favoured a position north of Greenland. Moreover, it precluded an East Greenland connexion with Svalbard because of the contrasts between the Mesozoic, especially Triassic successions known personally in each place. Indeed the North Greenland position for post-Devonian time met so many other requirements that it was readily accepted by most scientists. The conflict of evidence was then resolved by moving Spitsbergen from off East Greenland by strike-slip motion (a late Caledonian episode) the 1000 or so kilometres to the preferred later position off north Greenland as was then proposed (Harland 1965). The Cambridge work then moved from eastern and central to western Spitsbergen to attempt the correlation of the Hecla Hoek succession in Ny Friesland with that of older rocks along the west coast. The contrasts were formidable and credibility had to be stretched if detailed correlation was to be entertained. Not only did the western older rocks contrast with eastern Spitsbergen, but also with eastern Greenland. They could not then have been between the two. Therefore extensive strike-slip within Spitsbergen seemed to be necessary, not only along the Billefjorden Fault Zone (Harland 1969), but also along a postulated fault running south from Kongsfjorden (Harland 1975c). The hypothesis was thus of three provinces in Svalbard separated by two major sinistral fault zones (Harland & Wright 1979). I had already suggested at the San Francisco Arctic Geology meeting (1972 and 1973b) that as a general possibility Paleozoic faults could have bounded ancient slices of lithosphere, as in the Western Cordillera of North America. For example Cenozoic strike-slip was later based on tectono-stratigraphic comparisons for displaced 'terranes' in western North America. We had used the term province and American geologists adapted the term terrane for this concept. Subsequently the term terrane has become fashionable. Thus the postulated three Svalbard provinces are allochthonous terranes with respect to each other and to Greenland. Nevertheless the original use of province has a distinct significance that may be worth preserving, albeit with some qualification. The Svalbard hypothesis was not only that the terranes were relatively far travelled, but by their affinity with now distant terranes, their provenance was specified. They had in common certain characteristics with those distant terranes which is the criterion of a province. Therefore our palinspastic hypothesis for pre-Carboniferous Svalbard is restated as follows. Three parts of Svalbard in late Proterozoic time belonged to three Greenland and Canadian provinces. (i) A Central East Greenland Province united the Central East Greenland terrane and the East Svalbard Terrane. (ii) A North East Greenland Province united a North Greenland terrane and a Svalbard Central Terrane. (iii) A North Greenland-Pearya Province united Pearya in Ellesmere Island, terranes of North Greenland and the Svalbard Western Terrane. During Paleozoic time, and related to the M'Clintock, Caledonian and Ellesmerian orogenies, sinistral strike-slip motion brought the three Svalbard terranes together, docking in Late Devonian time so forming a new Svalbard composite terrane that has persisted to this day except t h a t i t drifted from north of North Greenland through Cenozoic time to the present position. Many details and modifications will unfold in the following chapters (especially Chapters 15 and 16), including the probability of at least two subterranes for each major terrane and possibly a further terrane to the east. (Fig. 3.10a & b) A further modification may now be necessary with the work of Smith & Armstrong (1997) who find such similarity between Ordovician faunas in Bjornoya and in northeast Greenland that the fourth enigmatic southern (Bjornoya) terrane may have been attached to Greenland through Paleozoic time and only joined Svalbard as it progressed away from Greenland in Cenozoic time.

3.5.2

Differential horizontal lithospheric motions

The relationship, fit and misfit, of terranes with characteristic tectonostratigraphic sequences through Late Proterozoic and Phanerozoic time was the most powerful motivation in proposing major sinistral strike-slip components of Paleozoic horizontal motions between lithospheric plates. The sedimentological argument came into play with respect to the Billefjorden Fault Zone (Harland 1969). The eastern margin of the Devonian graben was conceived as a Late Devonian strike-slip fault truncating the original wider fluviatile apron (Harland 1969; Friend & Moody-Stuart 1972). The palaeomagnetic argument either way has proved too crude or uncertain, The kinematic argument is that differential motions between irregular plates throughout the Earth require not only opposing motion of convergence and extension, but strike-slip and oblique motions combining components of strike-slip, convergence or extension. It was thus necessary to reinterpret the remarkable linear structures of western Ny Friesland from the hypothesis of compression and escape tectonics (Harland & Bayly 1958; Le Pichon e t al. 1977; Ohta 1994) to a mechanism of transpression once significant strikeslip motion was required. Transtension, with pull-apart basins was a natural complement (Harland 1971). The argument for Cenozoic dextral strike-slip to separate Svalbard and the Barents Shelf from Greenland began with the need to bring Svalbard to its present position from its Mesozoic position along the De Geer Fault. This had the additional and rather precise support from magnetic signatures plotting the course of ocean spreading. Both transpression for the West Spitsbergen Orogeny and transtension for related pull-apart basins have been invoked, accepted by most and resisted, for a time at least, by others. In this connection it should be reported that, against prevailing opinion, papers by Hanisch (1984) and Lyberis & Manby (1993a, b) have argued that the structures of the West Spitsbergen Orogen were formed not by Eocene transpression during the dextral translation of Svalbard from north of Greenland to its present position but in Late Cretaceous time by the earlier compression of Svalbard by a northward moving Greenland. A consequence of their hypothesis is that the orogenic structures do not deform Paleogene strata, but are unconformably overlain by them. This can be settled by simple inspection at critical localities as pointed out by Lepvrier (1994), Harland (1995) and Maher et al. (1995) which give more detail to support the original opinions of Hoel & Orvin (1937), Orvin (1934, 1940) and more recently of Dallmann et al. (1993) and Maher et al. (1996). This contentious matter is regarded here as settled, in spite of a partial retreat by Lyberis & Manby (1996), and need not complicate discussions of Paleogene tectonics in the remainder of this work. Strike-slip for hundreds of kilometres, to be energy efficient, requires relatively straight or regular curvature of the fault zone and that it be steeply dipping or near vertical. Once formed such a fundamental fault is a continuing source of weakness. It is therefore not unreasonable to invoke the reverse argument that straight fault zones that persist were probably once strike-slip zones and especially so if shear zones (often mylonitic) have survived denudation and can be observed as in some Svalbard faults. It may be impertinent to suggest that the reason why some structural geologists have been quite sceptical about transpression in Svalbard (whether Paleozoic or Cenozoic) is that whereas the compressive component is always evident, the evidence for a strikeslip component is generally not obvious. The case for strike-slip need not rely on structural evidence; indeed, as indicated above, it depends mainly on an appreciation of the whole regional tectonostratigraphic history. Structures have often been explained by tectonic history and not vice v e r s a . Indeed, the strike-slip component in transpression and transtension may not be obvious because the oblique motion is commonly resolved, or partitioned into compressive or extensional structures and strike-slip faulting (e.g. Harland 1971). A Geological Society of London symposium meeting 5-6 March 1997 amply confirmed the general acceptance of these processes.

SVALBARD'S GEOLOGICAL FRAME

(a)

AGE Q

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Fig. 3.10. (a) Simplified stratigraphy and geological evolution of Svalbard, reproduced with permission from Harland (in press), Svalbard in Encyclopedia of World Regional Geology. Formation names are in lower case, Group names are in upper case. Tectonic episodes in upper case italics. Numbers (not boxed) are thicknesses in km. AV, acid volcanics; BV, basic volcanics.

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Figure 3.11(a-h) reproduces the eight sketch maps published (1966) in a journal that hardly survived the second issue and so is not generally available (although in outline in Nature Harland 1967a). It gives an indication of early thinking along these lines. This was at a time when the major change in many minds was to recognize Mesozoic-Cenozoic continental drift (e.g. for the formation of the Atlantic Ocean). At the first Geology of the Arctic symposium held in Calgary in 1960, ocean spreading was already nascent (e.g. Heezen & Ewing 1961) even though the mid-ocean ridges were not thought by those protagonists to favour the concept of continental drift. But the debate was on (e.g. Harland 1961); but not concluded till the body of earlier opponents were converted

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0.1 I= . ~ ~ r 7.5 A, 0.5A. V var Alkhorn Lst -I A o . u / ~Dunderdalen Lovliebr. BV I ST JONS- Z ~ =Chamberlin. "~ 0,5 Moefjellet DstI FJORDEN ~ = ,~eHegga,, .~ Trondheimfja A B o g e g g1 - -. . . .I. ~. /// ~0~ Fl~yKalvenZ~=vimsodden' ~v "u-' Hansvika 0 . 5 ~ / ......

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STRATIGRAPHY OF SVALBARD by W.B. Harland drawn by P.A.D & C.S. Cambridge Arctic Shelf Programme Key (see also caption} * Biostratlgraphlc a g e of older rocks A. LateVarangertillites A EarlyVarangertillites @ Isotopic a g e in Ma Estimated biostratigraphic age, Mc I l l l Gap in stratal record

I g r a b e n deposlts

i. i.i. . ~\ BUCHANANISEN

Pg 2

p

SCHEMATIC (SIMPLIFIED)

{offshore Neogene)

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39

Im

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I I

I I"~' I s. I TER.

(e.g. Bullard et al. 1965). The palinspastic sequence in Fig. 3.11 amplified that of Harland (1965) and may have been the first modelling of continental drift in pre-Mesozoic time. Plate tectonics evolving as the concept for continental drift perhaps too long focused on Mesozoic and Cenozoic ocean spreading so it took some time for Palaeozoic plate motions and their related terrane contrasts and palaeo-oceans to be generally considered. Modifications, of course, were necessary as with the Iapetus Ocean in the Arctic (Harland & Gayer 1972, 1973) and the two and then three province concept (Harland 1975). These ideas were applied by some (e.g. Ziegler 1988), but they were mostly ignored or opposed but have remained with little challenge to the evidence.

40

CHAPTER 3

(b)

Fig. 3.10. (b) Schematic map of Svalbard to illustrate the hypothesis, referred to in this work, of Svalbard as a composite terrane derived from three or four Greenland provinces. Acronyms refer to fault zones: BBF, Breibogen; BFZ, Billefjorden; KHFZ, Kongsfjorden-Hansbreen; LFZ, Lomfjorden; RFZ, Raudfjorden; VL, Veteranen Line. Early Cretaceous dolerite sills are widespread and indicated on the map as blacked-in islands. Kong Karls Land (not indicated) is Triassic, and Kvitoya (outside the frame to the east of Nordaustlandet) is dominated by Caledonian metamorphic basement.

Late Devonian transport and arrival of Svalbard by Carboniferous time and the accompanying Ellesmerian Orogeny is shown in Fig. 3.1 l(d). Trettin (1991, p. 338) on the origin of the Ellesmerian Orogeny suggested 'Convergence of North America with another plate.., but that plate has not been identified with any assurance .... The convergence may have been orthogonal or oblique, and, in the latter case would have been accompanied by strike-slip, but pure strike slip without a component of convergence could not have caused such extensive deformation.' The Ellesmerian Orogeny was suggested (Harland 1965) to have resulted from the impact of Svalbard arriving by Devonian strike-slip and at the same time rucking up the Lomonosov Ridge by direct compression in its front against an ocean floor.

3.5.3

Polar and lithosphere wander, palaeoclimates

The palaeolatitude and relative longitude of points o f the Earth's crust, as well as their orientation have c h a n g e d t h r o u g h time. To distinguish polar a n d lithosphere w a n d e r i n g depends on having some global reference frame which, while difficult to argue, is not necessary for the p u r p o s e here. It is of especial interest to plot the

progress of Svalbard, and indeed its constituent parts, with respect to the N o r t h Pole at least t h r o u g h P h a n e r o z o i c time. F o r this purpose the figure by H a r l a n d , P i c k t o n & Wright (1976) has been r e d r a w n in Figure 3.12. It shows the progress of Svalbard n o r t h w a r d s t h r o u g h Silurian to Pleistocene time with palaeolatitudes changing from 10~ to 76~ The points for a curve show sudden shifts n o r t h w a r d of a b o u t 15 ~ near the S i l u r i a n - D e v o n i a n b o u n d a r y and a b o u t 20 ~ in Late Triassic time. This means only that there was a general shift related to g r o w t h and disintegration of Pangea. M o r e should not be read into it because the points were obtained often indirectly f r o m successive palinspastic maps. They say little a b o u t the m o t i o n s relative to n e i g h b o u r i n g lithosphere. The curve could be extended b a c k w a r d s to a near-equatorial position for V e n d i a n and C a m b r i a n time which simply makes the average n o r t h w a r d w a n d e r of say 75 ~ t h r o u g h say 500-600 million years. The evidence for Svalbard in tropical latitudes, say 500-600 Ma ago, was early suggested by sedimentological indicators in the whole Greenland, Svalbard, Scandinavian region (e.g. Bain 1960). Palaeomagnetic evidence for near equatorial latitudes, was first put forward for Greenland and Norway to support a low latitude in spite of extensive Early Vendian glacial

SVALBARD'S GEOLOGICAL FRAME

41

Cambrian and early Ordovician (500-470 Ma). The situation depicted here had probably already existed for some hundreds of millions of years, because in the dashed areas sediments commonly up to 20 km thick accumulated and only the uppermost beds are Cambrian and Ordovician. This is commonly known as the Caledonian geosyncline. Immediately preceding mountain belts are shown by vertical shading, with ancient continental areas blank.

Late Ordovician to Silurian (470- 400 Ma). Caledonian movements deformed the sedimentary and volcanic rocks of the geosyncline, with accompanying metamorphism and plutonism, to form the mountain belt shown here.

Mid-Devonian (c. 360 Ma). In the north by Devonian time the main compression was complete. Some plutonism continued, while uplift resulted in erosion, and deposition of the Old Red Sandstone in intermontane troughs (fine horizontal lines) which are related to fault zones (bold dashed lines) along which horizontal movements later occurred. In the Appalachian area widespread and intense deformation, metamorphism and igneous activity took place (the Acadian Orogeny).

Late Devonian to early Carboniferous (c. 350 Ma). At a a time not clearly defined, a series of parallel horizontal (transcurrent) fault movements took place. These have been demonstrated in Scotland, have been claimed in Newfoundland and are postulated in and near Spitsbergen. They all had the same sinistral (anti-clockwise) sense of movement, resulting in eastern Newfoundland, Europe and Spitsbergen moving north with respect to America and Greenland. There was probably also some sinistral rotation along this belt. From palaeomagneticevidence, Newfoundland turned through 30 ~ about this time (Black 1964), and the author tentatively suggests a similar rotation of Breggerhalveya (a smaller mass) in Spitsbergen. In addition to strike-slip movement, some minor compression affected the Spitsbergen area in late Devonian time (the Svalbardian folding). In East Greenland rather more disturbance is evident through Devonian and Carboniferous time. The Franklinian geosyncline of the Canadian Arctic was deformed in late Devonian and/or early Carboniferous time to form the Innuitian mountain belt (vertical shading).

.M.~

Fig. 3.11. Sequence of palinspastic reconstructions for the North Atlantic and Arctic from Cambrian to the present-day. Maps and captions are reproduced from Harland (1966) 'A hypothesis of continental drift tested against the history of Greenland and Spitsbergen', in Cambridge Research, 2, pp. 18-22, possibly the last publication of that journal. (a) Cambrian and early Ordovician; (b) Late Ordovician to Silurian; (c) Mid-Devonian; (d) Late Devonian to early Carboniferous; (e) Triassic; (f) Early Tertiary; (g) Mid-Tertiary; (h) present day.

Triassic (c. 210 Ma). The transcurrent faulting depicted in (d) resulted in the above relationships in the Arctic at latest by mid-Carboniferous time (c. 325 Ma). Whereas conditions in the (present) Arctic lands may have remained relatively stable until about 100 Ma (mid-Cretaceous time), a span of nearly 250 million years the Upper Paleozoic geosyncline in the Appalachians and central Europe was compressed in late Carboniferous and Permian time. This area (dashed) had achieved some stability by Triassic time. Thereafter it is possible that the Atlantic separation commenced; marine conditions appear to extend through the Arctic zone of potential separation. Extensive (Late Jurassic) dolerite intrudes earlier rocks in Spitsbergen and Canadian Arctic. The Lomonosov Ridge was still part of the Barents Shelf margin.

Early Tertiary (c. 50 Ma). (1) Cretaceous sediments, the oldest identified (marked K on the map), show the proto-Atlantic was already in existence, at least in the south, before Tertiary time. (2) The Brito-Arctic igneous province was active from end-Cretaceous to Early Tertiary time in the present continental margins (crosses). (3) Palaeomagnetic evidence suggests that Greenland moved away from North America (Labrador) in post-Triassic time. (4) Lower Tertiary rocks are folded in the intense orogenic belt of western Spitsbergen, probably in northeast Greenland, and also in the Canadian Arctic Islands (ornamented). This compression resulted from the northward movement of Greenland. (5) Continued northward movement of Greenland further separated the volcanic provinces of the British Isles and East Greenland and also of Disko and Baffin Islands. Sinistral movement on the Wegener Fault between Ellesmere Island and northwest Greenland and dextral movement now inferred in west Spitsbergen, separated Spitsbergen from northeast Greenland along the De Geer line (bold lines). (6) The resultant separation between Spitsbergen and Ellesmere Island accompanied a separation of the Lomonosov Ridge from the Barents Shelf by the formation of new Arctic ocean along a mid-Arctic zone of growth. (7) All of the above movements were accompanied by the growth of new ocean floor (shaded) along the mid-oceanic zones (small dashed lines); older oceanic crust is present in the North Candian Arctic Basin (stipple).

Mid-Tertiary (c. 3 0 - 2 5 Ma). The situation depicted in (f) of a separation of continental masses by the formation of new ocean floor (added along the mid-oceanic zone) continued throughout Tertiary time. Activity continued within the Brito-Arctic volcanic province with the growth of Iceland, Jan Mayen and Faeroe Islands.

.M,~ Fig. 3.11. (continued).

Present configuration of the continents and oceans. The North Canadian (Arctic) basin is the oldest, with the The North Eurasian and Atlantic basins being late Mesozoic to Cenozoic age. The short dashed lines indicate zones of present volcanic and seismic activity, i.e. active spreading zones.

SVALBARD'S GEOLOGICAL FRAME deposits (Harland & Bidgood 1959; Bidgood & Harland 1961; Harland 1964). Later palinspastic continental reconstructions supported this position (e.g. Smith, Hurley & Briden 1980). However, Smith (in press) suggests higher latitudes notwithstanding related halite indicators.

43

detail in Chapter 19 (Section 19.6.3). Jurassic temperatures were recorded as somewhat higher (16-10 ~) than Cretaceous (10-6~ The Early Cretaceous marine temperatures could be compatible with the evidence of the later glacial dropstones of Aptian-Albian becoming more abundant in Paleocene strata (Pickton 1981).

The climatic implications are significant for sedimentation in Svalbard. Harland, Pickton & Wright used the data to illustrate the latitudes of coal formations in Svalbard, from Late Devonian through late Eocene-Oligocene occurrences with at least ten intermediate stages with coal swamps, whenever other environmental factors were appropriate. Steel & Worsley (1984) and Worsley in Aga et al. (1986, pp. 22-23) adapted this same curve to explain other aspects in the sequence of sedimentation such as Bashkirian to Artinskian sabkha environments, at e. 30~ and high organic silica production at c. 40~ The only significant carbonate production in a clastic dominated sequence was in 'later Carboniferous and early Permian time' 'when Svalbard may have lain in the northern arid climatic belt'.

Pchelina (pp. 60-66 in Krasil'shchikov 1996) abstracted unpublished reports on Mesozoic Svalbard. She postulated four sedimentary cycles. (1) Early and Mid-Triassic time when the climate was hot and sufficiently arid so that vegetation cover played an insignificant part in the source area. Deposition took place in warm shelf seas. In postDevonian time high salinity of basin water decreased and transgression peaked in Anisian time with phosphate formation. Late Ladinian uplift took place. (2) Late Triassic and Early-Mid-Jurassic time when hot but intermittently humid climate prevailed. Carnian humid but cooler climate and lagoonal coal accumulation prevailed. (3) Late Jurassic to Berriasia~Barremian time with a humid but cooler climate and coal accumulation. (4) Aptian and Albian stages witnessed cool humid conditions accompanied by extensive transgression.

Renewed palinspastic map sequences by the Chicago group were plotted on a north polar projection (Rowley & Lottes 1988). These figured reconstructions at intervals, only from initial Cretaceous time, show latitudes for mid-Spitsbergen at 75~ rising to 76~ Paleogene time up to 78~ in Neogene time. A longer map series beginning at initial Triassic time by Smith et al. 1994 on a Molleveide equatorial projection has Spitsbergen in a marginal position and not so precisely located. Moreover, throughout Mesozoic time Svalbard was depicted there as separated from North Greenland. By adjusting Svalbard to a more likely position its latitudes (from 31 stage maps) show a rapid northward movement from 45 ~ to 60~ in Triassic time, Jurassic latitudes change from 60~ to 66~ Early Cretaceous 67 ~ to 70~ and Neogene to maximum at 80 and then back to about 78~ as at present.

3.5.4

Differential vertical lithosphere motions

Thickness of strata generally measures subsidence, especially when shallow water facies prevail at least at the beginning and end of the sequence. In a marine succession accumulating during many millions of years, the eustatic changes are probably reflected by changes in facies or gaps in the succession and so may be averaged out. Only by comparing successive isopach maps can the overall pattern of the subsidence be assessed. However, allowing that basins develop in contrast to neighbouring zero subsidence, it is meaningful to compare maximum or typical thickness for comparison through time. These are plotted on a linear time scale in Fig. 3.13 as was first attempted with much less data (Harland 1961). Evidence of deformation for tectonic activity is also indicated, but the older rocks need at least three separate columns for the different terranes and only some better known ones are selected here. It has been argued that at least two components in relative sea level change (in addition to eustatic changes) are necessary, namely subsidence due to lithosphere spreading e.g. in pull-apart basins with local cooling contraction and/or due to regional lithosphere contraction through cooling. A preliminary study of these problems concluded that the very long continued subsidence during Hecla Hoek deposition and in the accumulation of later platform sediments required regional lithospheric cooling. Similarly subsequent differential Late Cretaceous uplift required a thermal expansion mechanism in the mantle (Harland 1969). Figure 3.13 illustrates the contrast in a diagram from which precise quantitative conclusions are not permissible. However, three contrasting orders of magnitude are evident. The long narrow

Direct palaeomagnetic studies of Svalbard rocks (Harland 1959) have generally yielded disappointing results. An extensive sampling of pre-Devonian strata in 1958 seemed to be unrewarding because of later tectonism. Devonian strata were unstable and methods of washing were not then sufficient when Greenland and Norway indicated low latitudes in Vendian-Cambrian time. Watts (1985) investigated Early Carboniferous sandstones. Briden et al. (1988), without Svalbard data, concluded that relative E - W motion between Laurentia and Baltica is not discernible while differences of pre-Carboniferous (N-S) strike slip of more than 1000 km may be entertained but 'later strike-slip on this scale is no longer considered likely'. Watts's conclusions from Early Carboniferous Svalbard data are similar and palaeolatitudes of 14 ~ to 18~ were suggested. Other palaeomagnetic studies have been reported (e.g. Storetvedt 1972; Sandal & Halvorsen 1973; Levlie et al. 1984; Torsvik, Lovlie & Sturt 1985; Jelenska 1987, 1988-1989; Jelenska & Zawandowski 1986; Jelenska & Vincenz 1986). The palaeoclimatic implications of these palaeolatitudes are discussed in some of the historical chapters. Positive palaeotemperature determinations of sea water from stable oxygen and carbon isotopes (180 & ~3C) gave the results for Jurassic and Cretaceous fossils (Ditchfield 1996 et seq.). They are listed in some

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44

CHAPTER 3 CENTRAL BASIN

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vertical strips as in the p r e - D e v o n i a n Eastern terranes and in the Central Basin succession indicate slow subsidence averaging 25 m per million years (c. 0.025 m m a - l ) . This represents the consequence o f long c o n t i n u e d m a n t l e cooling in a stable tectonic environment. The m o r e rapid subsidence, at least 10 times that rate characterises a tectonically m o r e mobile e n v i r o n m e n t possibly with pull-apart basin subsidence. The extreme subsidence evident in the F o r l a n d s u n d e t G r a b e n is a syntectonic p h e n o m e n o n . Uplift is n o t so easy to m o n i t o r , but there is a parallel contrast between, for example, the slow tilting up to the n o r t h in Late Cretaceous time leading to an u n c o n f o r m i t y truncating Albian strata at an angle o f less t h a n 1~ within a time span of perhaps 35 million years a n d the orogenic uplift in a m u c h shorter time interval r e m o v i n g m a n y kilometres o f strata. The former was the result of m a n t l e heating in anticipation o f the thermal break up of L a u r e n t i a and caused Svalbard to rise above sea level at the N W corner of the Barents shelf exposing the strata that continue b e n e a t h the Barents sea.

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Fig. 3.13. Plot of subsidence against time for western, central and eastern areas. The linear time-scale is taken from Fig. 3.7 and is extrapolated. Three pre-Carboniferous terrane and two post Devonian terrane successions are selected and depicted diagrammatically. One square indicates approximate net subsidence of 250 m as measured by stratal thickness and the side of the sequence represents 10 million years. It does not indicate sediment volume. Because shallow water facies recur at intervals average sediment thickness thus represents net subsidence with respect to sea level. The diagram shows differences of an order of magnitude in subsidence rates. Lesser discrimination is not significant because of uncertainties in the time scale, age of sediments and the rough selection and plotting of thickness. A continuous vertical line implies one succession, sketched for this work.

PART 2 Regional descriptions Chapter Chapter Chapter Chapter

4 5 6 7

The Central Basin, 47 Eastern Svalbard platform, 75 Northern Nordaustlandet, 96 Northeastern Spitsbergen, 110

Chapter Chapter Chapter Chapter

8 9 10 11

Northwestern Spitsbergen, 132 Central western Spitsbergen, 155 Southwestern and southern Spitsbergen, 179 Southern Svalbard: Bjornoya and submarine geology, 209

Camp in snow on the southwestern flank of the icefield Lomonsonfjonna. In the distance the glacier Wilsonbreen flows down between Backlundtoppen on the right and Gotitsynfjellet on the left. The cliffs are mainly of late Neoproterozoic carbonates and tillites. Lomonsovfonna is a large snowfield in central Ny Friesland providing access by sledge down the many valley glaciers which it feeds. Photo M. J. Hambrey CSE 1981. (SP. 985a).

View from the icefield Lomonsovfonna, looking north to the high mountains of Ny Friesland from which the glaciers flow westward down to Wijdef]orden. The cliffs expose Proterozoic metamorphic Caledonian basement. Many mountains carry a snow cap resting on an uplifted and exhumed dissected preCarboniferous peneplane. The lone sledger (his companion being the photographer) demonstrates transport on a light-weight, sortie from a main camp. Photo M. J. Hambrey, CSE 1982 (SP 1257).

Typical view in the middle reaches of the glacier, Tryggvebreen, showing present-day transport by (Bombadier) snow scooters. The cliffs are of 'lower Hecla Hock' (Stubendorffbreen Supergroup) Proterozoic Caledonian basement. Snow scooters now provide basic transport, especially in the winter and spring months. In summer they are limited to high snow fields and the upper reaches of the glaciers they feed. Photo M. J. Hambrey, CSE 1982 (SP. 1351).

Cliffs of Akademikerbree dolostone/limestone, at Draken in Olav V Land (SE of Ny Friesland). The eight-wheel, tracked, amphibious vehicle is hauling a train of sledges over hard snow and ice; but it travels not so well in deep snow. It was mainly used for crossing marine mud flats from a supply boat, travelling up braided streams or across rotten bay ice. Routine man-hauling also favoured a train of sledges especially across uneven ground to spread the impact of obstacles. Four men would routinely haul two lightly laden 12 foot Nansen sledges and a pulka, divisible into two independent two-man parties. Photo M. J. Hambrey, CSE 1981 (SP10.70).

Chapter 4 The Central Basin W. B R I A N SIMON

R. A. K E L L Y ,

HARLAND ISOBEL

4.1 4.1.1 4.1.2 4.1.3 4.2 4.2.1 4.2.2 4.2.3 4.2.4 4.3 4.3.1 4.3.2 4.3.3 4.3.4 4.3.5 4.3.6 4.3.7 4.3.8 4.3.9 4.3.10 4.3.11 4.4

Geological frame, 47 Stratal succession, 47 Structural setting, 48 Geomorphology, 48 Van Mijenfjorden Group (Paleogene), 48 History of research, 50 Sedimentary-tectonic interplay, 50 Succession of the main outcrop, 51 Isolated outliers, 52 Adventdalen Group (Cretaceous-Jurassic) (S.R.A.K.), 52 Lithic units, 52 Eastern Nordenski61d Land and southwestern Sabine Land, 53 Sabine Land, 53 Heer Land, 55 Eastern Torell Land, 55 Sorkapp Land, 55 Wedel Jarlsberg Land and western Torell Land, 57 Western Nathorst Land, 57 Western Nordenski61d Land, 58 Central Nordenski61d Land, 58 Oscar II Land, 59 The Kapp Toseana and Sassendalen Groups (Liassic, mainly Triassic) (W.B.H. & I.G), 59 4.4.1 Lithic scheme for Kapp Toscana and Sassendalen groups in the Central Basin, 59

Svalbard rocks conveniently divide into younger and older rocks at about the initial 'Carboniferous' boundary. There are, however, latest Devonian strata in places continuous with Carboniferous sedimentation. The older rocks are tectonically as well as stratigraphically complex. Beginning with the sub-Carboniferous (peneplane) unconformity resting variously on Devonian and preDevonian strata, it expressly excludes any older rocks. The term basin as in Central Basin applied here is used in a structural sense for what amounts to a broad brachysyncline. The accumulated strata were also formed in sedimentary basins with shifting depocentres. The most obvious is the Paleogene sedimentary and structural basin commonly referred to as the Tertiary Basin. The Central Basin excludes the western and southwestern areas (Chapters 9 and 10) where older and younger rocks are caught up in the Paleogene West Spitsbergen Orogeny. It also excludes the areas, mainly in the islands in the east, where subsidence was less marked at first and tectonic platform conditions prevailed. The younger succession, Tournaisian through Paleogene (a span of about 330million years) has suffered only minor diastrophism in contrast to earlier events. Central Basin thus refers to the whole post Devonian cover or platform sequence in this study area. Most mineral prospects of economic interest in Svalbard belong to these younger rocks, from the many coal deposits of which Early Carboniferous and especially Early Paleogene horizons have been exploited. Furthermore, in the search for petroleum, source rocks of Late Carboniferous-Early Permian, Early to Mid-Triassic and Jurassic age have been identified and Late Permian, Late Triassic to Early Jurassic reservoir rocks. Official geological maps were available on three principal scales covering the Central Basin as follows: 1:1 M Series: Bedrock Map of Svalbard and Jan Mayen. Winsnes 1988. Sheet (Temakart No. 3). 1:500000 Series: Sheet 1 G. Spitsbergen, southern part. W. K. Dallmann (1993). 1 : 100 000 Series: Sheets B.7.G. Trekroner B.8.G. St Jonsfjorden. Bergh et al. (1993)

with contributions with

GEDDES

& PAUL

A. D O U B L E D A Y

4.4.2 Sassendalen to Storfjorden (southern Sabine Land), 61 4.4.3 Nordfjorden (S Dickson Land and E Oscar II Land), 62 4.4.4 Western Isfjorden (SW Oscar II Land and NW Nordenski61d Land), 62 4.4.5 Van Keulenfjorden (W Nathorst Land and N Wedel Jarlsberg Land), 62 4.4.6 Wedel Jarisberg Land, mid and southeast, 62 4.4.7 Sorkapp Land, 63 4.4.8 Kongsfjorden, 63 Biinsow Land Supergroup (Permian-Devonian) 4.5 (W.B.H, I.G. & P.A.D.), 63 Tempelfjorden Group (Permian) 4.6 (W.B.H, I.G. & P.A.D.), 63 4.6.1 Kapp Starostin Formation, 63 4.7 Gipsdalen Group (Carboniferous) (W.B.H, I.G. & P.A.D.), 66 4.7.1 Gipshuken Formation (Dickson Land Subgroup), 66 4.7.2 Wordiekammen Formation (Dickson Land Subgroup), 68 4.7.3 Minkinfjellet Formation (Campbellryggen Subgroup), 70 4.7.4 Ebbadalen Formation (Campbellryggen Subgroup), 70 4.7.5 Hultberget Formation (Campbellryggen Subgroup), 71 Billefjorden Group (Early Carboniferous), 71 4.8 4.8.1 Mumien Formation, 72 4.8.2 Horbyebreen Formation, 72 4.9 Structure and development of the Central Basin, 73

B 9.G. B 10.G. B.11.G. B.12.G. C.7.G. C.8.G. C.9.G. C.10.G. C.11.G. C.12.G. C.13.G.

Isfjorden, Ohta et al. (1991) Van Mijenfjorden, Hjelle et al. (1986) Van Keulenfjorden, Dallmann et al. (1990) Torellbreen, Ohta & Dallmann (1992+updated 1996) Dicksonfjorden, Dallmann et al. (1994) Billefjorden, Lauritzen et al. (1989) Adventdalen, Major et al. (1992) Breganzav~tgen, Salvigsen & Winsnes (1989) Kvalvagen, Dallmann (1991) Markhambreen, Birkenmajer et al. (1992) Sorkapp, Winsnes et al. (1993), description Dallmann et al. (1993) D.7.G. (not yet published) D.8.G. Negribreen, Miloslavskiy et al. (1992) D.9.G. Agardhfjellet, Miloslavskiy et al. (1993) Titles of map sheets in bold indicate that text accompanies the published map. Some of the titles were provisional at the date listed. 4.1 4.1.1

Geological frame Stratal succession

The Central Basin includes the main development of Carboniferous to Paleogene strata. The somewhat elliptical Central Tertiary Basin provides its southern focus. The succession may be simplified in seven groups (and two supergroups) as follows. Van Mijenfjorden Group, 2.5+ km (Paleogene) mainly continental clastics with some coal and some marine incursions. Nordenski61d Land Supergroup (defined here by the three groups) Adventdalen Group c. 800 m (Early Cretaceous-Jurassic) mainly marine clastics with continental horizons. Kapp Toscana Group, c. 250+ m (Early Jurassic-Late Triassic and latest Permian) mainly continental sandstones with condensed marine deposits.

48

CHAPTER 4

Sassendalen Group, c. 725 m (Mid- and Early Triassic and latest Permian) mainly marine shales. Biinsow Land Supergroup (defined here by the 3 groups:) Tempelfjorden Group, c. 380 + m (Late Permian) mainly marine shales. Gipsdalen Group, c. 850 m (Early Permian and Late Carboniferous and latest Devonian) marine carbonates and evaporites. Billefjorden Group, 316m (Early Carboniferous and latest Devonian) continental sandstones and shales with coals. It so happens that a major hiatus representing at least all of Late Cretaceous time, followed by a distinctive Van Mijenfjorden Group basal conglomerate, makes the Mesozoic-Cenozoic division easy to identify. Similarly a Late Permian hiatus of uncertain span followed by a dramatic change of facies, from Tempelfjorden Group with hard, pale, siliciclastic and chert facies to Sassendalen Group with soft, dark shales, allows an unusually clear division between traditionally Paleozoic and Mesozoic rocks. In each case the break is marked by only slight angular unconformity, but traces of diastrophism can be inferred. Indeed the whole succession has been referred to as an extensive platform sequence in contrast to the pre-Carboniferous strata and structure, but the Central Basin is distinguished from the Eastern Platform, as the names suggest. It is a region of greater subsidence during which the successive depocentres have moved around. Therefore the whole sequence described here and in later chapters in both basin and platform is referred to as the cover sequence. It overlies the mainly Devonian Liefde Bay Supergroup and the pre-Devonian basement. The classic section through much of the cover sequence is the Festningen profile (Festungs Profil) along the south coast of Isfjorden between Kapp Linn6 and Gronfjorden (Fig. 4.1).

4.1.2

Structural setting

As with most regional chapters here the limits are somewhat artificial, for descriptive convenience. The boundary to the north is simply stratigraphical. The 'postDevonian' platform cover is included here and the 'pre-Carboniferous' Old Red Sandstone and basement are excluded. The north of Svalbard was tilted upwards during Mesozoic time which resulted in the exposure of the older rocks to the north and their preservation in the Central Basin. The low dips result in a topographically controlled outcrop pattern. The western limit is complex with at least two boundaries. The later one is the fold and thrust front of the West Spitsbergen Orogen that postdates almost all the cover sequence. Cover strata are deformed within the fold and thrust belt, but to the west, uplift of the horst graben belt has allowed almost entire removal of the cover. However, the pre-orogenic platform sequence clearly extended westwards and there is some evidence of a NNW-SSE lineament affecting some sedimentation during that long interval. Lineaments have been referred to by various authors which may or may not refer to the same features. (i) Harland & Wright (1979) postulated a strike-slip fault boundary (the Central West Fault Zone) between their western and central provinces in preCarboniferous time, later redefined by Harland, Hambrey & Waddams (1993) as the Kongsfjorden-Hansbreen Fault Zone. Other fault zones with a similar early history, notably the Billefjorden Fault Zone continued intermittent dip-slip movement at least through Jurassic time. (ii) Mork and others (e.g. Mork et al. 1982) argued that the Pretender Fault east of Kongsfjorden extended southwards and became a significant sedimentary control in Triassic time. (iii) The southward extension of the Breibogen Fault has been suggested to exercise a similar, if not identical, control. All three fault proposals in this middle area have no direct observational support. The preference here is for continuing a postulated fault based on quite different and earlier evidence rather than inventing a new one for this function only. Without deciding

this question the lineament may be referred to as the Western Spitsbergen Fault Zone. The eastern boundary is less clear. It has been provisionally taken at the Lomfjorden-Agardbukta Fault Zone, which, while not an obvious boundary between allochthonous terranes, nevertheless continued in activity at least through the cover interval. The southern boundary is at the coastline. Even so this may not be entirely arbitrary because the Central Basin seems to close southwards as indicated by some isopachs and the greater thicknesses of less dense strata may have something to do with this particular elevation. One quite essential and unambiguous feature within the Central Basin is the Billefjorden Fault Zone which can be documented both in pre-Carboniferous rocks and in post-Devonian strata when it continued activity intermittently. Thus we have at least three N-S lineaments that traverse the platform. The Western Spitsbergen Fault Zone, the Billefjorden Fault Zone and the Lomfjorden Fault Zone. These played significant roles during different intervals within the cover sequence. In the nomenclature of this work the Spitsbergen Basin as a whole extended (at times) to the Lomfjorden Fault Zone in the east, east of which is the Svalbard Platform. It may be divided by the Western Spitsbergen and Billefjorden fault zones into the Western, Central and Eastern Basins. It is in this area that the Central Basin is named here and almost coincides with the 'Central Tertiary Basin' of many authors. However, this chapter includes the Eastern Basin as far as the Lomfjorden Fault Zone.

4.1.3

Geomorphology

The most obvious feature as seen on a map is the fjord pattern. Isfjorden from a relatively narrow gateway through the West Spitsbergen Orogen opens eastwards into a large branching sea. Similarly Bellsund divides inland into two large fjords and to a lesser extent Hornsund also. These in part reflect the softer Mesozoic strata dipping to sea level in the basin. On the other hand, the relatively consistent summit heights do not suggest that the Basin structures survived peneplanation in later Cenozoic time. De Geer (1909) and others have argued that the minor fault patterns defined the fjords. In so far as they can be identified this relationship is not obvious.

4.2

Van Mijenfjorden Group (Paleogene)

Paleogene strata are found in three main basin areas. (i) A western offshore wedge of sediment thins from the Knipovich ridge and thickens eastward towards the Hornsund Fault Zone. How much of this submarine succession is Paleogene and how much (probably the major part) is Neogene remains uncertain. This linear wedge extends along to the west of the West Spitsbergen Orogen and was most probably supplied by its erosion. (ii) A zone of graben extends just inshore and parallel to the coastline and appears to have formed within the orogen. Naturally enough it has a long and complex history, being best known in the Forlandsundet Graben and further south in the Calypsobyen outcrop south of Bellsund. Zones (i) and (ii) are treated in their regional context in Chapters 9 and 10. (iii) The Central Basin is the principal onshore outcrop of Paleogene strata and is the subject of this section being the uppermost unit of the Basin: the Van Mijenfjorden Group. Indeed it is this Paleogene group that conspicuously defines the brachysynclinal core of the Central Basin. It is bounded on the west by the West Spitsbergen Orogen which is intimately bound up with the sedimentary sequence. The Van Mijenfjorden Group was originally thicker and extended further west than the present outcrop. However there is one outlier to the northwest, the Ny-Alesund coalfield, exposed just under the thrust front of the orogen where it curves round and is

T H E C E N T R A L BASIN

49

CAROLINEFJELLET FORMATION

Das Festungsprofil (after Hoel & Orvin 1937) GRC)NFJORDEN

HELVETIAFJELLEI FORMATION "t3 .m (1)

(3_ O n," (.9 s

RURIKFJELLET FORMATION

0O I-UJ

Elatidesniveau

._1

uJ

Festning',

LI_

cO ARGARDHFJELLET FORMATION Z < .-)

Festningskjoeret~ "4%

!...

:3

(~.~ ~9,~'~~'~'~

~Festningen

- W I L H E L M O Y A FM

DE GEERDALEN FORMATION

~,~~~

9 o~ ~'~6~'~

BOTNEHEIA FORMATION .,.fee C6e's

CO

STICKY KEEP FORMATION

Ostre

,m !,...

\,o,~e'{~ Vestre

( Tvillingodde

VARDEBUKTA FORMATION

C3 O

E 1,...

(D

co

n

KAPP STAROSTIN FM cO .Q L_

/ N -4

i

Kapp Starostin( 0

500

I

I

1000m

GIPSDALEN AND BILLEFJORDEN GROUPS

I

Fig. 4.1. Reproduction of the Festningen profile as figured by Hoel & Orvin (1937), Das Festungsprofil auf Spitzbergen. Karbon-Kreide. Part 1. Vermessungsresultate. Skrifter om Svalbard og Ishavet 18, Plate 4. The current rock unit names have been added.

50

CHAPTER 4

overthrust towards the north or northeast. This curvature, convex to the NE, separates the Ny-Alesund Basin from the main Central Basin. By its location it is treated in Chapter 9 but it is probably an extension of the Central Basin and most authors include the strata within the Van Mijenfjorden Group.

4.2.1

History of research

Because the principal coalfields of Spitsbergen are Paleocene, as exposed in zones (ii) and (iii) above, the rocks have attracted attention from the earliest days and not least because the N-S basin is truncated by E-W fjords where the coal seams may be seen in cliff sections above sea level near the outer rim of the basin. Therefore even the earliest geological accounts refer to coal. Hoel (1920) wrote the first systematic descriptions of coalfields in Svalbard. The age of the deposits was subject to long-continued uncertainty as is discussed in Chapter 20. The plant remains were correlated with similar floras in the British Isles, Greenland and the Canadian Arctic all of which were first thought to be Miocene (e.g. Heer 1866-1880; Nathorst 1910) and then debated as Eocene and only later this century were correlated by marine fossils as Paleocene (Ravn 1922; Vonderbank 1970). The floras were thus eventually accepted as Paleogene rather than Neogene (e.g. Manum 1954-1966; Manum & Throndsen 1978-1986). For many years the succession of the Central Basin followed the early description given by Nathorst (1910). Indeed the same units were described in those terms by Orvin (1940) under the following heads: (6) (5) (4) (3) (2) (1)

Upper Plant-bearing Sandstone Series Flaggy Sandstone Series Upper Black Shale Series Green Sandstone Series Lower Dark Shale Series Lower Light Sandstone Series.

These six divisions formed the basis of the current lithic scheme with new nomenclature as introduced by the Norsk Polarinstitutt in the early 1960s (Major & Nagy 1964, 1965). Major & Nagy 1972 and largely confirmed by the SKS) (Fig. 4.2). Modifications were introduced from work by Russian geologists especially Livshits (1964-1974). The sequence of nomenclature is discussed in Chapter 19 and adopted in Section 4.2.3 below. The minor differences stem from the different facies as developed, for example, in the east and west of the basin. The tectonic setting, and especially the relationship between the long established Central Tertiary Basin and the newly elucidated West Spitsbergen Orogen was shown to be a product of oblique compression between Greenland and the Barents Shelf as they separated along a dextral shear zone (Harland 1965, 1966, 1969) to which the concept of transtension alternating with transpression was introduced (Harland 1971) and applied to the orogen (Lowell 1972). The West Spitsbergen Orogen itself being defined (Harland & Horsfield 1974), and related to the sedimentation (e.g. Kellogg 1975). The latest phase in these investigations has been the application of sedimentological principles to the successions with the publication of detailed logs from which the interplay of sedimentation source, supply and subsidence was related to the tectonic development of the basin. A series of studies indicated a close correlation between these events and the transtensional, then transpressional phases of the dextral shear zone (Steel 1977; Steel et al. 1981; Nottvedt 1985; Steel & Worsley 1984; Steel et al. 1985). Climatic and palaeolatitudinal considerations have been the subject of further studies as summarized (Harland, Pickton & Wright 1976; Worsley in Aga et al. 1986).

4.2.2

The sedimentary-tectonic interplay

The Central Basin and the West Spitsbergen Orogen provide an excellent example of how regional tectonics can throw light on the

Fig. 4.2. Map of the Paleogene outcrops in the Central Basin. Adapted with permission from SKS proposals for Lithostratigraphical Nomenclature o f the Tertiary Rocks of Svalbard (Dallmann et al. 1995) Figure 1. development of a sedimentary basin, and how in turn the facies within the basin can elucidate the related earth movements. The model proposed by Steel and others follows Harland's transtension-transpression model for the West Spitsbergen Orogen with

THE CENTRAL BASIN detailed sedimentological interpretation. Their conclusions are outlined below (Steel, Dalland et al. 1981; Steel & Worsley 1984; Steel, Gjelberg et al. 1985). The Paleogene succession thickens from 1.5 km in the northeast to 2.5 km in the southwest reflecting the greatest thickness where it is truncated by the orogenic sheared margin. A further 1.5 km of sediment may have accumulated on top of the preserved deposits and eroded as indicated by vitrinite reflectance studies. (i) The initial phase represented by the Paleocene Todalen (coal-bearing) Member, of the (lower) Firkanten Formation, was probably formed in a semi-enclosed embayment. Coal seams are abundant throughout the basin, being exposed above sea level at the rim of the basin where the formation rests unconformably on Early Cretaceous strata. (ii) The succeeding phase is one of transgression reflected by the two facies of the interfingering Endalen and Kalthoffberget members of the Firkanten Formation. This phase concludes with the pro-delta-shelf sandstones and siltstones of the Basilika Formation. The transgressive phase is thus marked by a sequence from coaly, through wave-dominated shelf, to pro-delta environments. Tectonically this was interpreted as a transtensional phase, so deepening the basin, with an axis approximating to the shear zone. This deepening reflected excess of subsidence over sedimentation in the absence of a compressive element that would provide an erosive uplifted source. The excess deepening probably exceeded any eustatic rise of sea level. These two phases were well understood from the thorough investigations of the coal-bearing strata, whereas the later story has less detail to support it. (iii) The following phase was clearly regressive (e.g. Kellogg 1975; Steel et al. 1981). The infill of the basin continued to thicken towards the shear zone, but with some sediment arriving from the direction of the shear zone rather than solely from the northeast. This situation is reflected in the shallow marine sequence of the Grumantbyen Formation to the N W and the offshore Basilika Formation to the SW. Sedimentation probably kept pace with slow subsidence as indicated by extensive bioturbation so heralding the latest Paleocene-Eocene orogenic uplift. (iv) The final phase is dominated by the Eocene transpressive regime which is indicated by upward coarsening successions, the marked and exclusive influx of sedimentation from the west and abundant syn-sedimentary deformation. The Gilsonryggen Formation comprises 2 0 0 - 4 0 0 m of black shales and occasional siltstones giving place to the Battfjellet Formation scenario as indicated above and capped by the Aspelintoppen Formation in which occurs the conspicuous liquefaction and soft-sediment deformation that indicates extreme instability in a coastal deltaic plain. Such observations were also noted by unpublished fieldwork in central Nathorst Land in 1974 (Pickton & Wright CSE).

4.2.3

51

Fig. 4.3. Stratigraphic units of the Van Mijenfjorden Group, with nomenclature recommended by SKS. Redrawn from SKS proposals for the Lithostratigraphical Nomenclature of the Tertiary Rocks o f Svalbard (Dallmann et al. 1995). Figure 2a which was revised from Steel et al. (1985). Central Basin units (CB1-6) are used in this work.

The succession of the main outcrops

The stratigraphic succession as recommended by Dallmann et al. (SKS, 1995) is summarized in Fig. 4.3. Van Mijenfjorden Gp (Major & Nagy 1964, 1972) comprises six formations, modified in detail. (6) Aspelintoppen Fm (Major & Nagy), >1000m (CB6). Poorly sorted sandstones, siltstones, calcareous shales, clay ironstones, thin coals and plant beds, altogether exhibiting soft sediment deformation, occur mainly in hill tops in the centre of the Paleogene basin. (5) Battfjellet Fm (Major & Nagy), 60-300 m (CB5). Well-laminated fissile and cross-bedded alternating grey-green to whitish sandstones interbedded with siltstones and minor black shales, some with marine bivalves. (4) Frysjaodden Fm (Livshits 1967), 200-400m (CB4a). This formation between CB5 the Battfjellet (sandstone) Formation and (CB3) the Grumantbyen (sandstone) Fm exhibits different successions between the NE and SW developments which has caused some confusion between Russian workers in the west and Norwegian in the east. The complex interdigitation of the strata reflects a changing pattern of sedimentation and provenance and the nomenclature has been resolved accordingly by SKS (1995) as follows.

In the NE the original Gilsonryggen Fm (of Major & Nagy 1964) is typically a black silty-shale succession with some chert pebbles and marine bivalves and it should be referred to as the Frysjaodden Fm (SKS 1995). In the SE the Hollendardalen (sandstone) Fm (Livshits 1967), (CB4), is a wedge of sandstone thickening to the SW and dividing the lower part of the Frysjaodden Fm. It was given formation rank because of the history of its name and its significance as indicating the first major sedimentation source in the west. A new name, Marstranderbreen Mbr (SKS 1995), was proposed for the shales of the Frysjaodden Fm beneath the Hollendardalen Fro. The shales above it being referred to as the Gilsonryggen Mbr up to another sandstone wedge from the west: the Bjornsonfjellet Mbr (Steel et al. 1981). The shale between this member and the Battfjellet Fm has no separate name and is presumably a digitation of the Gilsonryggen Mbr. The Sarkofagen Fm (Major & Nagy 1972) corresponding to part of the Hollenderdalen and probably the Morstanderbreen units is relegated to disuse. Hollendardalen Mbr, in the lower part which corresponds to the upper part of the green sandstone of the earlier Sarkofagen Fm. (3) Grumantbyen Fm (Livshits 1964), 200 45 m (CB3). Replaces the lower part of the earlier Sarkofagen Fm as defined further east (Major & Nagy 1964). It is a greenish (glauconitic) bioturbated sandstone.

52

CHAPTER 4

(2) Basilika Fm (Major & Nagy 1964, 1972), 10-350m (CB2). Mainly black and dark grey shales with occasional well-rounded pebbles of quartzite and chert and interbedded siltstones and sandstones near the base. (1) Firkanten Fin (Major & Nagy 1964), 100-170m. A coal-bearing sandstone unit interbedded with marine and non-marine siltstones and shales with a basal conglomerate resting with sub-parallel unconformity on Carolinefjellet Formation members. It has been divided into four members. Endalen Mbr (Steel et al. 1981, SKS), 40-100m (CBI.d) of stacked 4-5m bioturbated sandstone, cliff-forming strata with interbedded thin conglomerates, clay ironstones and minor shales, interfinger with underlying member. Kolthoffberget Mbr (Steel et al., SKS), up to 120 m (CBI.c) is a fine-grained lateral equivalent of the above member comprising organic-rich shales and fine bioturbated sandstones. Todalen Mbr (Steel et al., SKS), 60 m comprises three to five sequences of shale-siltstone-sandstone-coal. Gronfjorden Mbr (SKS), 4.5m is the irregular basal conglomerate with conglomeratic sandstones.

4.2.4

Isolated outliers

Southwest Sorkapp Land Oyrlandet Formation.

This is a poorly exposed sandstone, with some fault contacts, occurring at the southwestern tip of Sorkapp Land. It was regarded by Atkinson as part of the Central Basin succession and was correlated by Livshits (1992) with the Firkanten Formation and so mapped by SKS (fig. l a) and therefore part of the Van Mijenfjorden Group. The above name may be useful unless or until it is established as Firkanten Formation. It occurs well to the west of the main foldbelt which normally defines the western margin of the main Paleogene outcrop, yet it is still within the orogenic zone.

Eastern Outliers.

Whereas the Van Mijenfjorden Group main outcrop is bounded in the west north of Sorkapp Land by the eastern margin of the orogenic fold and thrust belt so forming a sharp, often vertical, limb to the Central Basin, its eastern boundary merges eastwards into the relatively flatlying platform mainly of Mesozoic strata. Consequently the Paleogene strata pass eastwards from the main outcrop into many outliers in the tops of the higher mountains and there is no knowing how far the Paleogene strata extended.

The Ny-,~lesund coalfield.

The outlier of undoubted Paleocene strata (Chapter 9) probably correlates with the one or two of its lower formations. Its Ny-Alesund Subgroup is classed within the Van Mijenfjorden Group of the Central Basin (SKS).

4.3

The Adventdalen Group ( C r e t a c e o u s - J u r a s s i c )

The Adventdalen Group of the Central Basin of Spitsbergen is up to 1800 m thick. Early, Mid- and Late Jurassic, and Early Cretaceous deposits are present. It rests on the Kapp Toscana Group with varying degrees of minor unconformity. In contrast the overlying Firkanten Formation of the Van Mijenfjorden Group, of Paleogene age, rests with increasing unconformity northwards on different members of the Carolinefjellet Formation; parts of the Mid-Albian and the whole of the Late Albian and Late Cretaceous deposits are missing (Nagy 1970). The Adventdalen Group forms a NNW-SSE-striking asymmetric syncline, which plunges gently to the SSE. Dips in the eastern outcrops are at a low angle and in the western outcrops are variable to steep. The main outcrop lies south of Isfjorden,

Sassendalen and Agardhdalen and runs south to Sorkapp Land, with outliers between Agardhbukta and Wichebukta. For convenience the minor outcrops on the north side of Isfjorden, southern Oscar II Land, are also included here.

4.3.1

Lithic units

Jurassic and Cretaceous strata of Svalbard are treated as a whole in Chapter 19. The following outlines the lithic units of the Adventdalen Group of the Central Basin which for this chapter is extended to the west and south to the outcrop limits.

Adventdalen Gp: Bathonian-Mid-Albian (Parker 1967). Carolinefjellet Fm, 1200+m marine shales to sandstones; Aptian to Albian (Parker 1967). Schiinrockfjellet Mbr, 70+ m, sandstones with minor shales and siltstones; Middle Albian (Nagy 1970). Zillerberget Mbr, 375+ m (Nagy 1970), shales and siltstones often with clayironstones and with minor sandstones; Early to Mid-Albian. Langstakken Mbr, 208m (Parker 1967), sandstones with minor siltstones and shales; Early Albian. Innkjegla Mbr (Parker 1967), 430 m mainly shales and siltstones in the upper part with shales and clay-ironstones in the lower part; Aptian-Early Albian. Dalkjegla Mbr (Parker 1967), 131 m laminated to thin bedded sandstones with alternating shales and siltstones; Aptian. HelvetiafjeHet Fm (Parker 1967), 53 m continental sandstones with coals and minor shales; erosive base; Barremian. Glitrefjellet Mbr, 69 m cross-bedded and rippled sandstones, carbonaceous shales, clay-ironstones and thin coals; Barremian (Parker 1967). Festningen Mbr, 30 m massive sandstones, often conglomeratic, with minor shales; Barremian (Parker 1967). Janusfjellet Subgroup, (Parker 1967): marine, predominantly argillaceous; ?Bajocian-Barremian Rurikfjellet Fm (Parker 1967), 176m shales to siltstones; BerriasianBarremian. Ullaberget Mbr (Rozycki 1959), sandy shales and siltstones with clayironstones and local calcareous sandstone; Valanginian?-Hauterivian. Wimanfjellet Mbr (Dypvik et al. 1991), silty shales with sideritic and calcareous concretions; Berriasian-Barremian. At the base in eastern Nordenskioid Land is the Myklegardfjellet Bed (Birkenmajer 1980), a glauconitic plastic clay with erosive base; Berriasian. Disturbed sedimentation has been related to the effects of an impact (Chapter 19.5.2) At the base in western Torell Land is the Polakkfjellet Bed (Birkenmajer 1975), conglomeratic sandstone; Volgian. Agardhfjellet Fm (Parker 1967), 243 m at type locality to 115m to west but > 49 m locally sandy-conglomeratic base. Revidalen, (Lindstromdalen), thickening but otherwise mainly shales to siltstones and fine sandstones; Bathonian Volgian. Slottsmoya Mbr (Dypvik et al. 1991), grey organic-rich shales with dolostone concretions; Kimmeridgian-Volgian. Oppdalshta Mbr (Dypvik et al. 1991), silts to fine sandstones; Oxfordian. Lardyfjellet Mbr (Dypvik et al. 1991), grey organic-rich shales with dolostone concretions; Bathonian-Callovian. Oppdalen Mbr (Dypvik et al. 1991). This basal unit of the Agardhfjellet Fm is generally calcareous and contains coarse clastics with conglomerates, sandstones, and siltstones, and locally phosphoritic and glauconitic, oolites; Bathonian-Callovian. It includes three beds. Dronbreen Bed (Dypvik et al. 1991), fine sands to silts; BathonianCallovian; Marhogda Bed (B/ickstr6m & Nagy 1985), with a maximum thickness of 1.5 m at the type locality near Diabasodden, south of Sassenfjorden. It is a microsparitic limestone, partially dolomitised and seriticized with quartz grains, chert ooids and glauconite. Brentskardhaugen Bed (Parker 1967), is at the very base of the member, with type locality on the south side of Sassendalen. It contains rounded fossiliferous phosphoritic, chert and quartz pebbles in a microsparitic ferruginous dolomitic cement. It reaches a maximum thickness of 1.35m east of Konusdalen, just west of Marhogda (B/ickstr6m & Nagy 1985). The base is erosional but without angular discordance on the Wilhelmoya Fm. The age is Bathonian. The nodules contain a diverse assemblage of bivalves, ammonites, belemnites and vertebrate bones of Toarcian-Aalenian age (B/ickstr6m & Nagy 1985). The erosive base.rests on the Kapp Toscana Group, whose youngest age is Toarcian (see below, 4.4).

THE CENTRAL BASIN The above units are described briefly from eastern Nordenski61d Land through the main outcrop clockwise along the east coast, where the sequence is only mildly deformed, south to Sorkapp Land, and then northwards through more disturbed strata of the western outcrops within, and in the vicinity of, the western deformation zone.

4.3.2

Eastern Nordenski61d Land and southwestern Sabine Land

In eastern Nordenski61d Land, the Adventdalen region and the mountains to its east, including Helvetiafjellet and Janusfjellet, are characterized by subhorizontal strata, with gentle westerly inclination. The original mapping by Major & Nagy (1964) of the area has been substantially revised and reinterpreted (Sheet C9G, Major et al. 1992). The readily weathered Janusfjellet Subgroup occupies the lower gound with a more intact outcrop pattern and the higher ground is characterized by the Helvetiafjellet Formation with Carolinefjellet Formation above, frequently isolated as outliers (Fig. 4.4). Cliff-forming sandstones crop out clearly in the Festningen Member of the lower part of the Helvetiafjellet Formation, and less prominently in the Sch6nrockfjellet, Langstakken and Dalkjegla members of the Carolinefjellet Formation. This pattern of outcrop continues southeastwards through Lardyfjellet in southwest Sabine Land to Rurikfjellet and Kapp Dufferin in northern Heer Land. The higher members of the Carolinefjellet Formation are progressively cut out northwards under the base of the Paleogene Firkanten Formation, which rests on the Langstakken and Zillerberget members; the latter is only represented in the very southeast of Nordenski61d Land. Thrusting from the west penetrates the Adventdalen Group, particularly at Arktowskyfjellet and Juvdalskampen where it affects the shales of the Agardfjellet Formation. The continuation of the Billefjorden and Lomforden lineaments affect especially the Janusfjellet Formation, causing thinning of sediment, and giving anomalous NNW-SSE striking anticlinal axes running under Bergmannhatten and just to the east of Tronfjellet. East of the Billefjorden lineament, the Agardhfjellet Formation is locally absent. Parker (1967) interpreted this as erosional, but it is at least in part due to decollment/thrusting (Parker 1966; Andresen, Haremo & Bergh 1988; Andresen e t al. 1992). A dolerite sill complex penetrates Triassic sediments around Diabasodden.

Carolinefjellet Fm at Langstakken, the type locality, is 768.5m (Nagy 1975), only the Dalkjegla, Innkjegla and part of the Langstakken members are represented and share the same type locality. Immediately under the Firkanten Formation is the: Langstakken Mbr, 208 m with eroded top; Dalkjegla Mbr, 131 m; Innkjegla Mbr, 429.5 m. Heivetiafjellet Fro. At Helvetiafjellet 54m of non-marine sediments (Parker 1967) comprise: Glitrefjellet Mbr, 49m sandstones to shales, thickening to 66m at Carolinefjellet; Festningen Mbr, 4m massive coarse grained to conglomeratic sandstones. Thickens to 14m on Carolinefjellet. Janusfjellet Subgp. The type section on Janusfjellet, 502 m comprises principally shales and siltstones (Parker 1967). It is marine throughout: Rurikfjellet Fro, 342m at Wimanfjellet is mainly argillaceous; contains two members: Ullaberget Mbr, sandstones with shales are thickest and more sandy in the northwest at Janusfjellet, 160m and generally thin to the south west, e.g. Lardyfjellet, 60m although are even thinnner in association with the Billefjorden and Lomfjorden faults (Dypvik et al. 1991). Between one and five coarsening upwards cycles are recognized. Bioturbation is characteristic, with some ammonites and belemnites; bivalves include mainly Buchia. Wimanfjdlet Mbr, grey shales with sideritic and calcite concretions, 182 m thick at the type locality; relatively poor in fossils; the base is formed by the: Myklegardfjellet Bed, thin plastic glauconitic clay crops out in eastern Nordenski61d Land including Lardyfjellet (40cm) and Glitrefjellet (50 cm) (Dypvik, Nagy & Krinsley 1992) and contains rare belemnites and Berriasian foraminifera (Nagy et al. 1990). The base is erosive. Possibly coeval with Mjolnir impact.

53

Agardhfjellet Fm (Parker 1967) is predominatly argillaceous, but two of the four members are sandy. Generally just over 200 m thick at Janusfjellet and Glitrefjellet, but thins to 100 m on the Billefjorden Fault lineament. Slottsmoya Mbr, grey organic-rich shales with siderite concretions (Dypvik et al. 1991), 90 m thick at the type section, siltier units in the upper part are characterized by ammonites, including Dorsoplanites and benthos. Oppdals~ta Mbr, silts to fine sandstones in three coarsening-upward cycles (Dypvik et al. 1991), 28 m thick at the type locality. Lardyfjellet Mbr, 35 m grey particularly organic-rich shales with dolostone concretions (Dypvik et al. 1991) at the type locality, macrofauna occasional. Oppdalen Mbr, 60m is the basal unit of the Agardhfjellet Formation, generally calcareous and containing coarse clastics, but locally oolitic (Dypvik et al. 1991), it includes three beds. Dronbreen Bed of fining upward sandy to silty clay with sideritic horizons, up to 60m thick (Dypvik et al.1991). Marhogda Bed with a maximum thickness of 1.5 m at the type locality near Diabasodden, south of the mouth of Sassenfjorden, a microsparitic calcarous sandstone, partially dolomitized and sideritized, with quartz grains, chert, ooids and glauconite (B~ickstr6m & Nagy 1985). Brentskardhaugen Bed (Parker 1967) forms the base of the member. At the type locality it is 130cm thick. It contains richly fossiliferous reworked phosphoritic concretions with cherts and quartz in a microsparitc ferruginous dolomitic cement (B/~ckstr6m & Nagy 1985). The base is erosional but without angular discordance on the Wilhelmoya Fro.

4.3.3

Sabine Land

The near horizontally bedded outliers northeast of Agardhbukta include the principal exposures on Agardhfjellet, Myklegardfjellet and Holmgardfjellet (Miloslavskiy 1993, D9G), where there is a complete sequence through the Janusfjellet Subgroup, capped with minor sandstone outliers of the Helvetiafjellet and Carolinefjellet formations. Agardhfjellet lies on the axis of a N N E - S S W minor syncline and Holmgardfjellet on a gentle anticline. The easternmost outcrop just east of Eistraryggen shows an overturned N N E - S S W striking syncline adjacent to a normal fault. There are extensive dolerite sills in the lower part of the Janusfjellet Subgroup in the west, north and east (Birkenmajer 1979). The lower part of the Janusfjellet Subgroup is similarly exposed to the north at D o m e n and Krogfjellet (Miloslavskiy e t al. 1993) and also Teistberget (Miloslavskiy 1992, D8G). At the last locality, N - S monoclinal flexuring and W S W - E N E normal faulting occur. The complete sequence from Glitrefjellet Member to Brentskardhaugen Bed (502 m) has been described from Myklegardfjellet (Birkenmajer 1980). His figure is comparable to a value of 555 m by Pchelina (1967) and of 473 m (based on Parker 1967 and additional data) from the same area.

Section at Myklegardfjellet (Birkenmajer 1980) Carolinefjellet Fm basal unit is present only on Agardhfjellet where carbonate-rich Dalkjegla Member crops out (Bjoroy & Vigran 1979). Helvetiafjellet Fm was formerly over 5 5 m thick and represents an overall fining-upward sequence on Myklegardfjdlet (Birkenmajer 1984) comprising: Glitrefjellet Mbr, 32 m comprizes sandstone shale alternations with minor conglomerates, coal shales, thin coal seams, rootlet horizons representing minor distributaries, channel lags, and interdistributary deposits, with a current direction from the northeast; Festningen Mbr, (c. 23 m) containing large-scale cross-bedded quartz sandstones and lag conglomerates with a sharp erosive base. The cross bedding is mainly planar, with planar and occasionally concave erosional surfaces with megaripples and some slumping. Together with current orientations these features indicate a fluvial system with source from the west. Janusfjellet Subgp, 417.5m is well exposed in Myklegardfjellet and contains eight macrofaunal horizons (Birkenmajer, Pugaczewska & Wierzbowski 1982). Rurikfjellet Fm, with type section on Agardhfjellet, 176m (Parker 1967), also on Myklegardfjellet, 203 m (Birkenmajer 1980), is predominatly shales with common sideritic and dolomitic concretions. It has not been subdivided north of Agardbukta. At the base is: Myklegardfjellet Bed plastic clay, 0.5-1.0 m with erosive base.

54

CHAPTER 4

Fig. 4.4. Geological map and cross-section of eastern Nordenski61d Land and Sabine Land, drawn by S. R. A. Kelly, based on Dallmann (1993) Geological Map of Svalbard 1.'500000, Sheet 1G. This legend serves also for Figs 4.5, 4.6, 4.7 & 4.8.

THE CENTRAL BASIN

55

AgardhfjeHet Fm is 245m on Myklegardfjellet (Birkenmajer 1980) and 241.5 m on Agardhfjellet (Parker 1967)). The section of Birkenmajer (1980) can be subdivided according to Dypvik et al.'s (1991) scheme: Slottsmoya Mbr, 110 m grey organic-rich shales with dolostone concretions; contains Fauna 8 including bivalves and the ammonite Pectinatites of Early Volgian age; Oppdalsfita Mbr, 61 m silts to fine sandstones with faunas 4, 6, 7, mainly of bivalves and 5 of belemnites; LardyfjeHet Mbr, 72.5 m return to grey organic-rich shales with Faunas 1 and 2 mainly of ammonites; Oppdalen Mbr shows a fining-up sequence; Dronbreen Bed, 40 m sands and silts overlying Brentskardhaugen Bed, 0.5m containing fossiliferous phosphoritic and quartzitic pebbles in a dark clayey matrix, resting with erosion on the Wilhelm6ya Formation.

4.3.4

Heer Land

A l t h o u g h m u c h o f the inner part of H e e r L a n d is ice covered, Helvetiafjellet a n d Carolinefjellet f o r m a t i o n s crop out extensively and almost horizontally f r o m the coast westwards, just reaching V a n Mijenfjorden, with only a small a m o u n t of Tertiary cover in the west (Salvigsen & W i s n e s 1989, C10G; Steel, Winsnes & Salvigsen 1989, C10G) (Fig. 4.5). The Janusfjellet F o r m a t i o n has a n a r r o w coastal o u t c r o p reaching s o u t h w a r d s to Kv~lv~gen ( D a l l m a n n 1991, C 11G), forming the base of the cliffs w h i c h are c a p p e d by Cretaceous strata. Extensive dolerite sills occur f r o m K a p p Dufferin n o r t h w a r d s , and affect the Janusfjellet Subgroup. Pavlov & P a n o v (1980) s u m m a r i z e d the geology of H e e r L a n d , recognizing some 971 m o f Cretaceous a n d 240 m of Jurassic strata. The V a l a n g i n i a n / H a u t e r i v i a n - A l b i a n sequences of K j e l s t r 6 m d a l e n , originally described by H a g e r m a n n (1925), and Kvalv{tgen and have been described within a biostratigraphic f r a m e w o r k by Pchelina (1967). The s o u t h e r n m o s t effects of the Billefjorden and L o m f j o r d e n F a u l t Z o n e s are seen in K j e l l s t r 6 m d a l e n a n d on Rurikfjellet respectively.

Carolinefjellet Fm reaches its maximum differentiation in southern Heer Land and northern Torell Land and all five members are recognized; the highest, the Sh6nrockfjellet Formation is restricted to this area and is of Mid-Albian age (Nagy 1970). Helvetiafjellet Fm (100 140m) fluvial sandstones of Kvalvfigen are characterized by quartzose lithic arenites with the quartz derived from the west and volcanics showing affinity with those of Kong Karls Land (Edwards 1978). At least four coals exist up to l m thick, of fusainsemifusainous durain (Pavlov & Panov 1980). Dinosaur footprints, attributed to a carnosaur, occur at Boltodden (Edwards, Edwards & Colbert 1978) in emergent point bar sandstones. Festningen Mbr sandstone forms a 20 m thick channel complex of planar to trough cross-bedded sandstones. The junction deposits of the HelvetiafjeHet Fm and the Janusfjellet Subgroup shows the existence of an unstable delta front which is affected by gravitational movement of slide blocks and is spectacularly exposed at Kv~lvagen (Nemec et al. 1988a). Whole blocks up to 80 m across and including both units have broken away from an arcuate scarp and rotated during down-slope movement from a delta-front. Janusfjellet Gp outcrops. Ullaberget Mbr a generally coarsening upwards sequence of shaley mudstones with thin massive, cross and plane bedded sandstones.

4.3.5

Eastern Torell Land

L o w westerly dips in the Helvetiafjellat and Carolinefjellet f o r m a t i o n s continue in eastern Torell L a n d . Janusfjellet S u b g r o u p no longer crops out on the coastal cliffs, whose base is n o w Cretaceous from Kvalvftgen south to H a m b e r g b u k t a . The higher parts of the coast a n d m o s t of the inland o u t c r o p is Paleogene (Birkenmajer, N a g y & D a l l m a n n 1991, C12G) (Fig. 4.6).

Carolinefjellet Fm is fully developed as in southern Heer Land and reaches 810m at Sch6nrockfjellet a near maximum recorded thickness of 840m at Kostinskifjellet and thickens further southwards beneath the Firkanten Formation unconformity (Nagy 1970).

Fig. 4.5. Geological map of the east coast of Spitsbergen from Agardhbukta to Hambergfjellet, drawn by S. R .A. Kelly, based on Dallmann (1993) Geological Map o f Svalbard 1:500 000, Sheet 1G (see Fig. 4.4 for key).

Schiinrockfjellet Mbr, 83m at the type locality on Sch6nrockfjellet, predominantly cliff-forming fine grained sandstones, with rare bivalves and crinoids. Becomes muddier southwards and passes laterally into the Zillerberget Mbr (c. 350 m). Langstakken Mbr, up to c. 50m but passes laterally into Innkjegla or Zillerberget Mbr southwards. Innkjegla Mbr, c. 120 m. Dalkjegla Mbr, c. 50 m. Helvetiaqellet Fro. 4.3.6

Sorkapp Land

The o u t c r o p p a t t e r n in S o r k a p p L a n d increases in complexity s o u t h w a r d s and westwards, whose interpretation is h a m p e r e d by considerable ice cover e.g. in the central S o r k a p p f o n n a (Winsnes et. al. 1993, C 13G). In the northeast, b r o a d N N W - S S E fold axes are

56

CHAPTER 4

Fig. 4.7. Geological map and cross sections of the Adventdalen Group in Sorkapp Land, drawn by S. R. A. Kelly, based on Dallmann (1993) Geological Map o f Svalbard 1: 500000, Sheet IG and Winsnes et al. (1993) Geological Map of Svalbard 1 ."100 000, Sheet C13G.

Fig. 4.6. Geological map and cross sections of the Adventdalen Group in Wedel Jarlsbert Land and western Torell Land, drawn by S. R. A. Kelly, based on Dallmann (1993) Geological Map of Svalbard 1-500 000, Sheet 1G.

seen in Cretaceous rocks, but dips remain low and there is a small a m o u n t of n o r m a l faulting. In the south of Sorkapp L a n d N W - S E normal faulting and associated folding cause disjunct outcrop pattern. At K i k u t o d d e n on the coast and inland on Keilhaufjellet, E-dipping (20-45 ~) Jurassic and Cretaceous rocks are exposed. The top of the Cretaceous rocks crops out on the west and n o r t h flanks of D u m s k o l t e n , where a small synclinal fold again brings the Tertiary to sea level and Cretacous outcrop is interrupted on the coast. The Cretaceous-Jurassic sequence next appears in a comparable situation, although steep and overturned in proximity to a N N E - S S W - s t r i k i n g thrust, from Gideanoyfjellet and Smalegga to the south coast of inner H o r n s u n d at Brepollen (Fig. 4.7).

A series of small outliers is largely controlled by normal faulting in south and central western Sorkapp Land. Janusfjellet F o r m a t i o n outliers resting on K a p p Toscana G r o u p occur on the summit of Kistefjellet, Oyrlandssleira (with Helvetiafjellet Formation), and Stormbukta. In northeast Sorkapp Land, a Cretaceous-Jurassic sequence resting on Triassic, crops out in a series of thrust slices on Lidfjellet. In a largely biostratigraphical account, Pchelina (1967) described the whole Jurassic and Cretaceous sequence, based on a generalized section t h r o u g h eastern Keilhaufjellet, eastern foot of Kistefjellet and shore cliffs at Austerbogen. Only in parts can this be related to m o r e recent lithic schemes.

Carolinefjellet Fm reaches its greatest measured thickness under the Firkanten Formation erosion at Tromsobreen where 850m have been recorded (Nagy 1970). Here the the Zillerberget Member is the highest unit recognized. The sandy Sch6nrockfjellet and Langstakken Members do not reach this far south. Zillerberget-Innkjegla Mbr undifferentiated shales and siltstones, c. 850 m at Havkollen and thins to 630 m at Keilhaufjellet. Dalkjegla Mbr sandy siltstones and argillite alternations thin southwards from c. 40 m to 60 m. Late Aptian heteromorph ammonites occur (Pchelina 1967).

THE CENTRAL BASIN

Helvetiafjellet Fm, 58 m comprises fining-upward cycles at Kikutodden (Edwards 1976). Pchelina (1967) identified macrofloras of Barremian to probable Aptian age. Glitrefjellet Mbr, 33 m two principal sand-mudstone cycles occur representing channel to floodplain deposits. Festningen Mbr, 25 m two alluvial channel sandstone cycles with conglomeratic bases occur, with transport direction principally from the NW and SW-W. Janusfjellet Subgp Rurikfjellet Fm is not clearly divided. Pchelina (1967) recognized three lithofacies in the Hauterivian part: at the top sandy siltstones (c. 45 m), in the middle a carbonate siltstone (c. 15 m) and at the base mudstones (30 m). The middle calcareous unit may well be related to calcareous units at comparable levels in Kong Karls Land and offshore. Clayey siltstone with carbonate concretions occupy c. 175m of Valanginian to Volgian strata. There is possibly a sandy mid-Volgian interval (c. 15 m). Agardhfjellet Fm, c. 170m mudstones to muddy siltstones with early Volgian to Callovian (probably also Bathonian) fossils. It may be possible to recognize a slightly coarser median. Oppdalsfita Mbr, with Oxfordian fossils, of c. 60 m thickness. Brentskardhaugen Bed, 0.2-0.3m (Pchelina 1967) overlies c. 10m of arenacous and conglomeratic Kapp Toscana Group sediments.

4.3.7

Wedei Jarlsberg Land and western Torell Land

J u r a s s i c - C r e t a c e o u s strata strike N N E - S S W f r o m inner H o r n s u n d in western Torell L a n d , to V a n K e u l e n f j o r d e n n o r t h e r n Wedel Jarlsberg L a n d , with o u t c r o p interrupted by ice cover and m a d e complex by N N W - S S E thrust-faulting ( D a l l m a n n et al. 1990a, b B l l G ) . M u c h of the central to n o r t h e r n part o f the area was m a p p e d originally at 1:50000 by Rozycki (1959). The broadest outcrops are of Cretaceous strata at the west flank o f the Central Basin and include Zillerberget at the north. H e r e easterly dips are m o d e r a t e to low. Except in the north, Jurassic outcrops are n a r r o w a n d dips are steep to overturned. A r o u n d P e n k b r e e n and R e i n o d d e n in the north, Jurassic strata are repeated twice because of faulting. The f o r m e r wider distribution of Jurassic outcrops is shown by the outliers west o f P e n k b r e e n and Finsterwalderbreen. The outcrops of n o r t h e r n W e d e l Jarlsberg L a n d are all influenced by thrusting. T h e wide Janusfjellet o u t c r o p is related to the m a i n o u t c r o p of H u m p v a r d e n a n d is caused by a series of folds. The outcrops of Tilaberget a n d Leinbreen are outliers directly affected by thrusting, while the R e i n o d d e n o u t c r o p is a n o r m a l faulted outlier with an o v e r t u r n e d Janusfjellet a n d Helvetiafjellet sequence. Elsewhere dips are n o r m a l l y low a n d only locally are steep to overturned. Small Janusfjellet S u b g r o u p inliers occur west o f Storbreen (Birkenmajer, N a g y & D a l l m a n n 1991) at south Grimfjellet and west M e z e n r y g g e n in gently folded strata c o m p a r a b l e to that o f Cretaceous strata in n o r t h e a s t S o r k a p p Land. Intrusive dolerite dykes occur on the south o f Bellsund (Hauser 1982). General descriptions of the J u r a s s i c - C r e t a c e o u s sequence in southwest Torell L a n d have been given by R o z y c k i (1959) a n d Birkenmaj er (1975).

Carolinef]ellet Fm totals about 700m thickness in northern Wedel Jarlsberg Land (Nagy 1970), with the four lower members represented on Zillerberget. Major sections have not been measured in the south, although the base is recognized at Polakkfjellet where dark arenaceous shales of the Dalkjegla Member occur, and equivalent strata crop out on Blfikettane and Isskiltoppane (Birkenmajer 1975). Zillerberget Mbr, 210 m at the type locality comprizes distal shelf shales and siltstones with minor sandstones and clay-ironstone concretions. The top of the member contains Middle Albian ammonites and is eroded under the Firkanten Formation unconformity. Langstakken Mbr, 40 m but passes laterally into Innkjegla or Zillerberget Member southwards. Innkjegla Mbr, 321m shales to shales with siltstones containing Early Albian ammonites, including Arcthoplites and Freboldiceras faunas. Dalkjegla Member, c. 130m sandy siltstones. Helvetiafjellet Fm comprizes three principal coarsening-upward cycles in western Torell Land (Birkenmajer 1975, 1984).Typical Glitrefjellet and Festningen member lithologies are present in some localities, not so clearly

57

demarcated at Cholmfjellet where thick alluvial channel facies in the upper part of the Formation (as opposed to the base), indicate the proximity of an easterly source for clastics from the Hornsun&Sorkapp High. The base of the Helvetiafjellet Formation is generally marked by erosion and at Bendefjellet the top of the Janusfjellet Subgroup is penetrated by rootlets from above, suggesting subaerial conditions. The basal Helvetiafjellet Formation unit in the area is usually a non-marine shale-sandstone unit. Festningen Mbr where it can be recognized, varies in thickness at Hyrnefjellet (50-60 m), Bendefjellet (45 m) and Polakkfjellet (20 m).

Janusfjellet Subgp Rurikfjellet Fm thickens northwards. There is marked thinning to less than 100m centering on southern Wedel Jarlsberg Land, and forming the Serkapp Hornsund-High. In northern Wedel Jarlsberg Land thicknesses increase to over 200 and over 400 m respectively in these formations. Ullaberget Mbr comprizes regressive sandstones of the Formation. In the southwest at Bendefjellet the member is only 6 m thick, comprising a single unit of bituminous and glauconitic sandstone with plant detritus; at Hyrnfjellet it is 10-20m and 65m at Polakkfjellet. Northwards it reaches c. 150m at Reinodden and 119.5m at Jurakammen. At Bendefjellet it is penetrated by rootlets originating in the Helvetiafjellet Fm. Wimanfjellet Mbr was originally recognized in this area as the Tirolarpasset Mbr (Rozycki 1959), with type section at Jurakammen where it is 187.5m thick. It comprizes uniform siltstones and shales with clay-ironstones. The base of the Member is the: PolakkfjeHet Bed, which is only recognized in Wedel Jarlsberg Land, a conglomerate of clasts of ferruginous sandstones and quartz pebbles, which rests on a significant erosional base. The break probably lies within the Volgian stage or at its base on an eroded Kimmeridgian surface (Birkenmajer 1975; Birkenmajer & Pugaczewska 1975). The bed is 5m thick at Polakkfjellet and stated to be 46.34m in the Jurakammen section (Birkenmajer 1975). Dypvik et al. (1991) correlate this bed with comparable sandstones in the formation below. Agardhfjellet Fm corresponds in this area to the Ingebrigtsenbukta Mbr of Rozycki (1959) with type section at Ingebrigtsenbukta on the south coast of Van Kuelenfjorden. At Jurakammen the unit is 285 m thick comprising shales and siltstones with clay ironstone concretions. It is widely exposed, but thins southwards to Polakkfjellet (150m), Hyrnefjellet (110 m), south Fonnryggen (60 m), Somovfjella and Somovaksla (both 40 m) (Birkenmajer 1975). Although the upper members of the formation have not been identified in the area, the Oppdalen Mbr is recognized at the base. Forming the base of the Agardhfjellet Fm is the Brentskardhaugen Bed which varies locally in lithology: at south Fonnryggen it is a poorly cemented fossiliferous phosphorite pebble concentrate (0.1-0.2 m); at Hyrnefjellet it contains black phosphorite pebbles in black shale matrix or is a wellcemented conglomerate of quartz, fossiliferous phosphorite and ferruginous ooids with siderite, grading up into sandstone (0.2-0.5 m). The latter may indicate existence of the Marhogda bed. At Skiferkammen the Brentskardhaugen Bed shows reverse grading and at Tilasberget in the lower part it is normally graded and in the upper part reverse graded (Maher 1989) with no angular discordance at its base. No positively Jurassic fossils have been reported from this area, (Krajewski 1992).

4.3.8

Western Nathorst Land

In M i d t e r h u k e n , west N a t h o r s t L a n d ( D a l l m a n n et al. 1990, B11G; Hjelle et al. 1985, B10G), a simple, m a i n l y easterly dipping o u t c r o p of A d v e n t d a l e n G r o u p lies between the K a p p T o s c a n a a n d V a n M i j e n f j o r d e n groups with several m i n o r Helvetiafjellet F o r m a t i o n outliers resting on the Janusfjellet Subgroup. The o u t c r o p is u n i n t e r u p t e d between V a n K e u l e n f j o r d e n and V a n Mijenfjorden. The b r o a d JanusfjeUet S u b g r o u p o u t c r o p is caused by strikeparallel N - S fold axes, a syncline o f w h i c h passes t h r o u g h the Helvetiafjellet o u t c r o p on A n n a b e r g e t . M u r o s k o has described dolerite intrusions into b a s e m e n t rocks on the M i d t e r h u k e n peninsula (Fig. 4.8).

Carolinefjellet Fro, although a relatively full sequence of the Dalkjegla to Zillerberget members is represented in western Nathorst Land, the youngest date is Early Albian (Nagy 1970). Helvetiafjellet Fm Festningen Mbr coarse massive sandstones rest sharply on the Janusfjellet Subgroup.

58

CHAPTER 4 ,,,,,,,,,,,,,,,,,,,,

,

Kvaevefjellet III~._~_oldiabukta

t!l!!

// ////

/,, OSCAR I I / / LAND

~ fjellei:ll'~r )

~

Ullaberget Mbr is 151.5m thick at the type locality on Ullaberget, and is at its maximum development. It comprizes regressive sandy shales and siltstones with minor micaceous sandstones. Janusfjellet Subgp Oppdalen Mbr is represented on Midterhuken by over 7m of calcareous sediments with ooliths and is comparable to the Marhogda Bed (Maher 1989) but in the middle of which there is the Brentskardhaugen Bed (1 m), immediately above a stromatolite rich layer. (Krajewski 1990, 1992).

o.e'aof, yal Bohemannesset

yf

~ //

Is fj o r d e n

Sylodden

Van

kk ~

Bellsund

Midterhuken ~ s

%

Western Nordenski61d Land

In western Nordenskiold Land, the Adventdalen Group crops out from between Berzeliusdalen on the north shore of Van Mijenfjorden, where it is largely obscured by drift, northwards to Gronfjorden, with the classic Festningen sequence on the south shore of Isfjorden. To the east the Cretaceous sequence dips at low angle, eastwards under the Tertiary unconformity. To the west the Janusfjellet Subgroup and the Helvetiafjellet Formation dip at moderate to high angle, and include the near vertical sandstones at Festningen itself. The Festningen section is one of the most accessable Jurassic-Cretaceous sections on Svalbard with an almost completely exposed sequence of Adventdalen Group strata exposed in low level coastal cliffs (Frebold 1928; Frebold & Stoll 1937; see Fig. 4.1).

k

A

4.3.9

Erdmanflya

Ramfjellet

Mijenfjorden ~

~ : : . j . . i.~LAN r

A' Erdmannflya 1000

~~l,,fr,1,

....

0m -1000 -2000

Gronfjorden

Carolinefjellet Fm is at its thinnest at Festningsodden, where only 180 m including only the lowermost two members occur under the basal Tertiary erosion surface. Steel, Gjelberg & Haar (1978) interpreted coarsening upwards cycles as of lower delta front facies. Inkjegla Mbr Dalkjegla Mbr Helvetiafjellet Fm non-marine sequence includes: Glitrefjellet Mbr, sands and silts are recessive. Steel, Gjelberg & Haar (1978) demonstrated distributary channel sandstones; Festningen Mbr, crevasse channel sandstones, levees, crevasse splays and interdistributary bays massive sandstones are well exposed in the, 29.5 m at Festningen itself. Frequent conglomerates indicate reworked earlier Jurassic, Permian, Carboniferous and possible Early Paleozoic deposits represented elsewhere on Spitsbergen (Parker 1967). Fossil footprints indicate the presence of a dinosaur, Iguanodon (de Lapparent 1962). Janusfjellet Subgp Agardhfjellet Fm Rurikfjellet Fm Marhogda Bed, 40 cm Brentskardhaugen Bed is only 5 cm thick although it thickens southwards to 45 cm at Vardebreen (B/ickstr6m & Nagy 1985) and crops out on the south coast at Flathaugen (Maher 1989). It occurs above transgressive sandstones of the Wilhelmoya Formation.

g w

1000 Om -1000 -2000

Fig. 4.8. Geological map and cross sections of the Adventdalen Group in Oscar II Land, Nordenski61d Land and Nathorst Land, drawn by S. R. A. Kelly, based on Dallmann (1993) Geological Map of Svalbard 1: 500000, Sheet 1G and for the Ramfjellet section, based on Ohta et al. (1991) Geological Map of Svalbard 1:100 000, Sheet B9G.

4.3.10

Central Nordenski61d Land

The relatively few published records of the sequence from the centre of the Central Basin beneath the Paleogene cover include the sequence of the Grumant borehole which was made on the north side of Colesbukta. Cretaceous to Jurassic rocks were encountered at depths from 4 5 0 m to 2620m and were described from a biostratigraphical basis by Shkola et al. (1980):

Early Cretaceous, 1000 m: Aptian-Albian, 120 m upward-fining sands to argillites. Barremian, 115 m sandstones with coals. Hauterivian, 115 m silts becoming sandier upwards. Valanginian, 220 m argillites. Berriasian, 160 m argillites with siderite. Jurassic, 350 m: Volgian, 165 m argillites Kimmeridgian, 110 m argillites Oxfordian, 45 m Callovian, 30 m sandy silts. Burial palaeotemperatures of the Early Cretaceous and Late Jurassic rocks were of 160-190~

THE CENTRAL BASIN

4.3.11

Oscar II Land

The outliers of Oscar II L a n d represent the relics of the n o r t h e r n closure o f the o u t c r o p o f the A d v e n t d a l e n G r o u p of the Central Basin. Jurassic strata rest on Triassic intermittently exposed from the west side of Y m e r b u k t a , t h r o u g h Ramfjellet and Syltoppen to Y o l d i a b u k t a , a n d is disrupted by faulting. Cretaceous rocks occur at a n d near the coast n o r t h of E r d m a n n f l y a and B o h e m a n n e s s e t a n d on Ramfjellet a n d Syltoppen (faulted) (Ohta et al. 1991, B9G). At B o h e m a n n e s e t coal was m i n e d in the early 1920s. The o u t c r o p p a t t e r n at Sylodden matches that at Festningen, on the south side o f Isfjorden, but is offset by thrust faulting in Isfjorden w h i c h strikes N N E - S S W . Here a complete Janusfjellet S u b g r o u p sequence, capped by Helvetiafjellet sandstones, occupies a syncline striking N N W - S S E , parallel to the b e d d i n g strike. The JurassicCretaceous sequence is repeated in the outliers by several thrust fault slices in the higher part of Ramfjellet, but separated by a thrust fault f r o m S - S E (5-20 ~ dipping Cretaceous, including Helvetiafjellet, sandstones. The most northerly outcrops are B o h e m a n n e s s e t a n d Kv~evefjellet where a low-dipping sequence of Janusfjellet a n d Helvetiafjellet is cut by a series of thrusts exposed on the higher ground.

Helvetiafjellet Fm Glitrefjellet Mbr, at Bohemanesset macroflora is abundant including Elatides, (Sveshnikova & Budantsev 1969) Ginkgo, Podozamites, Pseudotorellia and 'Sciadopitys-like' leaves (Bose & Manum 1990).

Festningen Mbr RurikfjeUet Fm Ullaberget Mbr, 100 m is predominantly sandstone, comprises two coarsening upwards cycles showing hummocky cross-stratification, followed by parallel lamination and intense bioturbation (Dypvik et al. 1991; Hvoslef, Dypvik & Solli 1986; Oxnevad 1985).

Wimanffjellet Mbr Mycklegardfjellet Bed is present (Dypvik et al. 1991). Agardhfjellet Fm is well exposed at Bohemanflya where it is particularly thick (260 m), Dypvik et al. (1991) gave the following sequence: Slottsmoya Mbr, 75 m upward-fining sands shales; Oppdalshta Mbr, 95 m paper shales and a 30 m thick organic-rich muddy sandstone; the latter generally macrofossil-rich, including bivalves, ammonites and belemnites; Lardyfjellet Mbr, 20 m paper shales; Oppdalen Mbr, 60m reaches its maximum thickness at Syltoppen, mainly Dronbreen Bed, sandy shales, becoming sandier upwards; and at the base, the Brentskardhaugen Bed, rests with erosion on the Wilhelmoya Formation.

4.4

The Kapp Toscana and Sassendalen Groups (Liassic, mainly Triassic)

Strata of the K a p p T o s c a n a a n d Sassendalen groups crop out extensively in S v a l b a r d - the larger area being in the east where they are described in C h a p t e r 5. H o w e v e r , the Central Basin contains the type sections for all except the u p p e r m o s t (Wilhelm o y a ) formations. W i t h the exception o f part of this f o r m a t i o n , w h i c h ranges up to T o a r c i a n age, the two groups are wholly Triassic in age. T h e n o m e n c l a t u r e a n d classification o f lithic units are discussed m o r e fully in C h a p t e r 18 a n d the f a v o u r e d scheme is a d o p t e d here. Place names are s h o w n on Fig. 18.1.

4.4.1

Lithic scheme for Kapp Toscana and Sassendalen Groups in the Central Basin

The distribution of rock units is s h o w n in the fence d i a g r a m (Fig. 4.9).

Kapp Toseana Group. This unit was originally defined as a formation with two members (Buchan et al. 1965) and they were raised in rank to

59

group (Harland et al. 1974) so that the Group was constituted by the two formations: De Geerdalen and Tschermakfjellet from which a third formation (Wilhelmoya) was distinguished at the top (Worsley 1973). The fence diagram (Fig. 4.9) shows the uniform strata throughout. Plant remains are common everywhere. Ammonites, bivalves and some gastropods occur in marine beds where also fish and reptile remains and trace fossils (Rhizocorallium and Diplocraterion) are found. Ages from Late Ladinian for the Tschermakfjellet Formation through Norian and Rhaetian for the Wilhelmoya Formation are indicated. Wilhelmnya Formation (Worsley 1973). Worsley included the Brentskardhaugen Bed at the top of his formation. It is not, however, described in the type section nor is it evident in the main development of the formation in the Eastern Platform (Chapter 5). Moreover that 'Lias conglomerate' was originally included in the Janusfjellet Formation (Parker 1966) and although subsequently taken within the De Geerdalen Formation (e.g. Buchan et al. 1965), it has latterly resumed its position as a basal conglomerate of the Janusfjellet Subgroup (e.g. Dypvik et al. 1991) and that is adopted here. The consequence is that whereas the restricted Wilhehnoya Formation is well developed in the Eastern platform and the Brentskardhaugen Bed is traceable through the Central Basin, the beds below it in the Central basin are not so easily distinguished lithologically in the Central Basin from the body of the de Geerdalen Formation as originally described. The age range of the Wilhelmoya Formation is probably Norian-Toarcian (Worsley 1973; Bjaerke & Dypvik 1977; B~ickstr6m & Nagy 1985). The Wilhelmoya Formation differs in its terriginous fraction from the rocks below being more mature in its sandstone content. It it much thicker in the Eastern Platform (Chapter 5). In the Central Basin its maximum thicknesses is in the south. It is much thicker in the Eastern Platform (Chapter 5). In the Central Basin its maximum thickness is in the south. De Geerdalen Formation (Buchan et al. 1965). Originally defined as a member this unit is largely a non-marine sequence of fine- to mediumgrained grey-green plant-bearing sandstones, weathering greenish and brown, laminated to massive, interbedded with varying amounts of grey silty shales, shaly siltstones and harder calcareous siltstones. It includes the Plateau flags of Gregory (1921) and possibly the Fosse Sandstone of Hoel & Orvin (1937). It was named from the valley (De Geerdalen) to the west of Botneheia. The composition is generally of immature sandstones with 50% or less quartz, 33% feldspar and up to 30% of rock fragments (Pchelina 1965a; Lock et al. 1978). Mork, Knarud & Worsley (1982) reported that the predominantly sandy De Geerdalen Formation consists of recurrent small and large scale sequences, upward coarsening from grey shale to very coarse grained sandstone, where at the top they were reworked by waves and bioturbated. They show channelling, hummocky and herringbone cross-bedding with many erosive contacts. Most types of ripples occur as well as lenticular, wavy and flazer bedding. A high energy environment is indicated by protective burrows and mud clasts. In the lower sandstones, cementing is by interstitial clay minerals. Tschermakfjeilet Formation (Buchan et al. 1965). Similarly, at first a Member of the Kapp Toscana Formation, this unit is distinctive but not uniformly extensive. It included the Oozy Mound Beds and Upper Nodule Bed of Gregory (1921), the Upper Daonella layers of Wiman (1910a). The upper part included the Halobia shales of Stolley (1911), his Nathorstites Niveau and his Lingula Sandstone. It is the upper Saurian Niveau of Wiman (1910b) and the Lindstroemi Sandstone of Frebold (1930b). This formation is indeed a richly fossiliferous unit with an age range from Late Ladinian to (Late) Carnian. This unit is recognized in the eastern and southern outcrops of the Central Basin and further east in the Eastern Platform. The dark shales, siltstones and fine sandstones are distinguished by their small red-weathering clay ironstone concretions which contain a rich ammonite and bivalve fauna. The unit is overlain by the lowest hard sandstone of the De Geerdalen Formation. It is underlain by the siliceous siltstone marker at the top of the Botneheia Formation. The unit also appears in southern Spitsbergen (shown as such in sections by Mork & Worsley 1979) and was then named the Austjokelen Formation by Mork et al. 1982). These southern facies differ in having fewer siderite nodules and occasionally none. It is noteably absent in the western fold belt where the thicker and sandier facies dominate. Sassendalen Group (Buchan et al. 1965). The Sassendalen Group was defined as comprising three formations: Botneheia, Sticky Keep and Vardebukta all from the Central Basin. The two upper formations comprised the Kongressfjellet Subgroup; but this is not often used. It is a clearly defined unit between the Kapp Toscana Group above and the

60

CHAPTER 4

Fig. 4.9. Fence diagram showing the distribution and thickness variation of the Sassendalen and Kapp Toscana groups, based on Buchan et al. (1965) except for section south of Kapp Lee. Tempelfjorden Group below except where there is a lithological gradation upwards into the Tschermakfjellet Formation. The three formations have been recognized satisfactorily throughout the Central Basin as was demonstrated by Mork & Worsley (1979). However, Mork, Knarud & Worsley (1982), in the course of a systematic sedimentological analysis, while adopting the same threefold classification, changed the nomenclature significantly, some aspects of which are not followed here. For example, because in Barentsoya and Edgeoya, where the three formations are not readily distinguishable and where Lock et al. (1978) for this reason introduced a single Barentsoya Formation (Section 5.7) Mork et al. (1982) reduced the three original formations to members within

the Barentsoya Formation which then became in effect the Sassendalen Group. The seven new names that were introduced for the other outcrops of the Sassendalen Group will be mentioned in the description of the three original Formations which defined the Group. Kongressfjellet Subgroup. The Subgroup comprises the Botneheia and Sticky Keep formations. Botneheia Formation, 157m (Buchan et al. 1965). The type section was measured at Vikinghogda and is well exposed to the west on Botneheia. The formation is traceable throughout Spitsbergen except that it is not so distinctive in the northeast (Section 5) and in Sorkapp Land. It is a dark grey shale sequence weathering blue black and dark grey.

THE CENTRAL BASIN The upper part is of papery, laminated, bituminous (2-11% TOC) shales or occasionally concretions of grey silty limestone (Daonellenkalk of Mojsisovics 1886). They form a distinctive escarpment (Escarpment Shales of Gregory 1921). They are equivalent to the Oil Shale Series in Edgeoya (Falcon 1928), and the Ptychites beds of Spath (1921). The lower part is of softer shales with siltstone interbeds and small phosphatic concretions, generally less than 2 cm diameter, weathering blue black, these increase to 50% of the rock at the base. Mork et al. refer to the upper part as Blanknuten Beds i.e Blanknuten Member of the formation. On the west coast they refer to the formation as the Bravaisberget Formation with an upper Somovbreen Member and a lower Passhatten Member. Their Bravaisberget Formation appears to be mainly represented by their Karentoppen Member. Bivalves are especially common and the age range would be Anisian to Early Ladinian. Sticky Keep Formation, 121 m (Buchan et al. 1965). In the type section on Vikinghogda and to the east in Sticky Keep this formation is distinguished from the softer Botneheia beds above by a cliff-forming yellow-weathering topographical ledge of siltstone. Septarian concretions (10cm to l m diameter) are common in the lower part. Ammonoids, bivalves and bone fragments occur throughout. A Smithian-Spathian age is thereby indicated. The formation includes the Posidonomya layers of Nathorst (1910) the same as the Posidonomya limestone of Mojsisovics (1886), the Fish Niveau of Wiman (1910, Arctoceras layers of Stolley (1911), the lower Posidonomya shales of Spath (1921), the Arctoceras horizon of Frebold (1930a) The upper part contains the lower Saurian Niveau and Grippia Niveau ofWiman (1910a) and (1928), and the Saurian Bed and the lower part of the Upper Posidonomya Shales of Spath (1921). The lower part contains the lowest Nodule Bed of Gregory (1921), the Anasibirites horizon of Spath (1921) and the Goniodiscus nodosus horizon of Frebold (1930a). There are thickness variations over the Billefjorden Fault zone. In the west coastal sections Buchan et al. (1965) distinguished two members at Iskletten in Oscar II Land. However two such members can be traced through most of the Central Basin though not into the Eastern Platform. Kaosfjellet Member, 76 m is named from the chevron folding at lskletten and fi'om Kaosfjellet. It is of laminated shaly siltstones alternating between softer yellow-weathering and harder grey-weathering. Iskletten Member, 154 m is the lower uniform shaly part of the Sticky Keep Formation and is characterized i.a. by grey septarian limestone concretions especially in the upper part. Fossils are not common except in the concretions. The Sticky Keep Formation is readily distinguished in the Festningen section at the south western entrance to Isfjorden, however, Mork et al. (1982) have used a local name for it (the Tvillingodden Formation). Above the Hornsun&Sorkapp High they gave a further name: the Kistefjellet Formation. The extra nomenclature was introduced to match their sedimentological interpretations of the sequence. Vardebukta Formation, 253.5m (Buchan et al. 1965). The lowest formation of the Sassendalen Group (and below the Kongressfjellet Subgroup) is best exposed at Vardebukta in the Festningen section to the west of the basin where the type section was described. It is characterised by sandstones with interbedded siltstones and shales. Similar lithologies are evident in Sassendalen and Dickson Land but the sections are often obscured by scree and float, from which a similar stratigraphy can be deduced. The best exposure in the east may be at Deltadalen which name Mork et al. introduced for a parastratotype section and named it there as a unit (member) in place of the original Vardebukta Formation as mapped there. The Vardebukta Formation has been divided into two members: Siksaken and Selmaneset. Siksaken Member, 104 m (Buchan et al. 1965) is named from Siksaken with its sharp folds in Oscar II Land and described from Iskletten composite section. The member consists of alternating grey calcareous, silty limestone, calcarenite, light grey and white sandstone, hard siltstones and calcareous shales. Fossils are common. It is distinguished by its contrasting hardness from the more shaly member below. The member includes the Pseudomonotis shale and Retzia limestone of Lundgren (1887) and the synonymous Hustedia limestone of Nathorst (1910). Selmaneset Member, 136m (Buchan et al. 1965) is named from the eastern promontory at the entrance to Trygghamna in Oscar II Land. It is of dark grey often calcareous silty shales and distinguished from the overlying member by its lesser resistance to weathering. Fossils are not common, however, the member was thought by Buchan et al. to include the Myalina Shale of Lundgren (1883) and the Claraia zone of Frebold (1936).

61

The Vardebukta Formation if present on the Hornsundet-Sorkapp High is very thin (28 m Worsley & Mork 1978) and may be represented by the Brevassfjellet Bed of Mork et al. (1982). In the following regional outline the lithologies as described above are sufficiently c o n s t a n t for the principal f o r m a t i o n s as described above to be recognized t h r o u g h o u t m o s t of Spitsbergen as d e m o n s t r a t e d by B u c h a n et al. (1965) a n d M o r k & Worsley (1979). C o n s e q u e n t l y to s u m m a r i z e the lithologies in each of the following areas w o u l d involve m i n o r variations on basic characteristics so similar as to confuse rather t h a n to clarify. There is, of course, far m o r e i n f o r m a t i o n in the original description of each section. B u c h a n et al. (1965) described the lithologies and the positions of fossil collected. M o r k & Worsley (1979) and M o r k et al. 1982 logged detailed sedimentary characters for sedimentological interpretations. The thickness estimates of each unit are derived from the published s e c t i o n s - the B u c h a n et al. values as recorded are in italics. The other values have generally been estimated f r o m the published sections.

4.4.2

Sassendalen to Storfjorden (southern Sabine Land)

F r o m Sassenfjorden along the cliffs and slopes of the m o u n t a i n s south of Sassendalen and t h r o u g h to A g a r d h b u k t a in S t o r f j o r d e n is the belt of outcrops w h e r i n the strata between the P e r m i a n K a p p Starostin a n d the Jurasssic A g a r d b u k t a f o r m a t i o n s are well displayed. T h e y are nearly fiat-lying and tectonically have suffered relatively m i n o r disturbances. M o r e o v e r their fossiliferous facies has c o n t r i b u t e d to this being a classic area of Triassic studies. In these circumstances it was n a t u r a l to establish the lithic scheme of rock units here as described above. In the stratigraphic history of Svalbard the Mesozoic interval was a time of relative tectonic stability with the result that the same lithic units can be m a p p e d t h r o u g h o u t Svalbard with only m i n o r variations. The Sassendalen G r o u p strata rest with slight disc o r d a n c e on the T e m p e l f j o r d e n G r o u p b e n e a t h a n d the K a p p T o s c a n a G r o u p strata are c o n c o r d a n t with the overlying Adventdalen G r o u p albeit with a distinctive n o n s e q u e n c e between them. These rocks crop out in a wide b a n d t o w a r d s the n o r t h e a s t (see Fig. 18.1). T h e y are less well k n o w n there except at W i l h e l m o y a and Hellwaldfjellet where the u p p e r part of the K a p p T o s c a n a G r o u p is especially well represented with the type section of the W i l h e m o y a F o r m a t i o n . But this is treated in the following chapter (5) as part o f the Eastern Platform. In addition to earlier investigations as by G a r w o o d & G r e g o r y (1896) and G r e g o r y (1921) there have been m a n y biostratigraphical and palaeontological studies, for example: the saurian w o r k s o f W i m a n (1910-1933), the a m m o n o i d studies o f L e h m a n n a n d colleagues (Weitschat 1986; Weitschat & L e h m a n n 1978, 1983; Weitschat & D a g y s 1989), and the bivalve studies of C a m p b e l l (1994) (see C h a p t e r 18). The following notes especially the thicknesses are based largely on the w o r k o f B u c h a n et al. (1965), M o r k & W o r s l e y (1979) a n d M o r k et al. (1982). F r o m these sources the succession in this Sassendalen to S t o r f j o r d e n sector is a p p r o x i m a t e l y as follows: Adventdalen Gp Kapp Toscana Gp Wilhelmoya Fm, in area c. 120 Tumlingodden Mbr, 60 m Transitional Mbr, 33 m Bjornbogen Mbr, 19 m Basal Mbr, 7 m De Geerdalen Fm, c. 380 m (at Wilhelmoya) 190m (at Botneheia) Tschermakfjellet Fro, c. 93 m at Vikinghoda, c. 63 m at Botneheia Sassendalen Group Botneheia Fm, 170-146 m at Sticky Keep, 157 m at Vikinghogda, 129 m at Botneheia Sticky Keep Fin, 120m to ?150m at Sticky Keep, 121 m at Vikinghogda, 70 m at Stensi6fjellet

62

CHAPTER 4

Vardebukta Fro, (Deltadalen Mbr of Mork et al.), 130m at Deltadalen, 115 m at Vikinghogda, 125 m at Stensi6fjellet, 129 m at Sticky Keep (102+m at Botneheia) Tempelfjorden Group. Kapp Starostin Formation

4.4.3

Nordfjorden (S Dickson Land and E Oscar II Land)

Successions thin over the old Nordfjorden Block as compared with both east and west. They are seen best to the east in the extensive and accessible outcrops of southern Dickson Land as at the classic Kongressfjellet section Tschermakfjellet and Rotundafjella but also to the west in eastern Oscar II Land at Bertilryggen and Sveaneset. In each case the regional southerly dip has the effect that the De Geerdalen strata have been mostly removed where they dipped into Isfjorden. Kapp Toseana Gp De Geerdalen Fm Tschermakfjellet Fm, 50 m at Tschermakfjellet, 70 m at Kongsressfjellet Sassendalen Group Botneheia Fro, 129 m at Tschermakfjellet, 126 m at Kongressfjellet Sticky Keep Fro, 133m at Rotundafjellet, 120 m at Tschermakfjellet, 112m at Kongressfjellet Vardebukta Fro, 61 m at Tschermakfjellet, 101m at Rotundafjellet, ?70m at Kongressfjellet Tempelfjorden Gp Kapp Starosfin Fro.

4.4.4

Western lsfjorden (SW Oscar II Land and N W Nordenskiiild Land)

West of the Nordfjorden area is the West Spitsbergen orogenic foldbelt which runs parallel to the coast from Kongsfjorden to Hornsund. In this the whole Late Paleozoic-Mesozoic successions are steeply dipping and so of narrow linear/',IS outcrop. Whereas this gives the opportunity in E - W coastal section often to traverse near-vertical strata there are also likely to be structural complications. Of these the section at the southern entrance to Isfjorden, the Festningen section (Hoel & Orvin 1937), is perhaps the best known stratigraphic profile in Svalbard with near-vertical mid-Carboniferous to Paleocene strata. The Triassic rocks being less competent than those below and to the west have therefore been somewhat thrust so that precise correlation and thickness are in question. A further consideration is the fact that the Paleogene orogen coincides approximately with a significant thickening and coarsening of the Triassic strata to the west so that the western margin of the basin has been uplifted and eroded. The fence diagram (Fig. 4.9) demonstrates this thickening with resumption of the Kapp Toscana succession at the top. It could be argued that the postulated Kongsfjorden-Hansbreen Fault which bounds the Nordfjorden High on its west has something to do with this thickening.That fault would have a long pre-Carboniferous history and possibly locate the eastern margin of the Paleogene Orogen. M o r k e t al., on the other hand, postulated an extension southwards of the Pretender Fault which extension seems to have no other supporting evidence. Indeed, there is no need for a fault to mark the thickening. The distance between the two contrasting stratal thicknesses used by M o r k e t al. is 40 or 50 km which, with a thickness difference of up to 500 m represents a maximum cumulative gradient of 1% (less than one degree). The slope could be increased by aligning the fault more closely to the two isopach points but then it would not align with the proposed faults. Moreover, M o r k e t al. did not use the southern Oscar II Land data of Buchan e t al. These gave intermediate thicknesses, i.e. not so thick values as at Festningen. Adventdalen Gp Kapp Toscana Gp. Formations are not distinguished. The group thickness at the northern entrance to Isfjorden is 207m (i.e in southern Oscar II Land) and at the southern entrance (Festningen section) is 327.5 m.

Sassendalen Gp Botnieheia Fm (= Bravaisberget Fm at Festningen of Mork et al.) Somovbreen Mbr is 262m at northern entrance and 243.5m at southern entrance to Isfjorden. Sticky Keep Fm (= Tvillingodden Formation at Festningen of Mork et al.) with a Skilisen Bed near the middle): 130 to 230m at northern entrance, 300.5 m at southern entrance to Isjforden. At the northern entrance two members were defined by Buchan et al. Kaosfjellet Mbr, 76m in N 122m in S Iskletten Mbr, 154m in N 178.5m in S Vardebukta Fin (Buchan et al. and Mork et al.), 233 m in the N 253.5 m in S. Two members were distiguished by Buchan et al. in southern Oscar II Land. Siksaken Mbr, 104m at Iskletten in N; 95.5m in S Selmaneset Mbr, 129m at Selmaneset in N; 158m in S.

4.4.5

Van Keulenfjorden (W Nathorst Land and N Wedel Jarlsberg Land)

The outcrops at the entrance to the two fjords branching eastwards from Bellsund similarly show thick successions within the foldbelt. In Western Nathorst Land at Bravaisberget north of Van Keulenfjorden is a key section measured by both Buchan e t al. and M o r k e t al. as follows and Buchan e t al. combined it with the section south of the fjord at Kapp Toscana. Adventdalen Gp Kapp Toscana Gp, 200 m Wilhelmoya Fm, c. 7 m De Geerdalen Fro, 193 m (Tschermakfjellet Fm not distinguished) Sassendalen Gp Botneheia Fm (= Bravaisberget Fm, Mork et al.), 215 m. Sticky Keep Fm 312m (Tvillingodden Fm of Mork et al. c. 280m). Kaosfjollet Mbr, 92 m Iskletten Mbr, 220 m Vardebukta Fro, 142-160m Siksaken Mbr, 62 m Selmaneset Mbr, 80 m

Tempelfjorden Gp. In northern Wedel Jarlsberg Land the cliff sections at Reinodden and at Ahlstrandodden were described in lithic and biostratigraphic terms by Nakazawa e t al. (1990). They followed and amplified in detail the Sassendalen units of Buchan et al. (1965). In broad outline the succession was given thus: Kapp Toscana Gp Sassendalen Gp Botneheia Fro, 175 m Sticky Keep Fm Kaosfjellet Mbr, 268 m Iskletten Mbr, 85 m Vardebukta Fm Siksaken Mbr, 68 m Selmaneset Mbr, 35 m Tempelfjorden Gp.

4.4.6

Wedel Jarlsberg Land, mid and southeast

The same strip of deformed Triassic strata continues parallel to the orogen. Sections were logged by Rozyicki (1959) at Passhatten and by M o r k & Worsley at Somovfjella and Tvittopane, both in mid Wedel Jarlsberg Land. Treskelen sections, north of inner Hornsund, have been available to many scientists in the Treskelodden promontory to the north of inner Hornsund. In mid Wedel Jarlsberg Land, the sequence from Rozycki (in Buchan e t al. 1965) follows. Kapp Toscana Gp, Rozicki c. 204 m Wilhelmoya Fm, c. 40 m (estimated) De Geerdalen Fro, c. 100 m

THE CENTRAL BASIN

Sassendalen Gp Botneheia Fm, 220m Sticky Keep Fm, ?83 m Vardebukta Fm, 65 m At Treskelen Kapp Toscana Gp, 150-160 m Wilhelmoya Fin, c. 23 m De Geerdalen Fro, c. 103 m Tschermakfjellet Fro, c. 34 Sassendalen Gp Botneheia Fro, 111 m or 105 m Sticky Keep Fin (85 m or 110 m) Vardebukta Fin (101 m or 80 m) Sticky Keep and Vardebukta Fms combined, 190 m

4.4.7

Sorkapp Land

Sorkapp Land contains interesting contrasts which may be summarised in four zones in all of which Sassendalen Group strata appear, it not being easy to ascertain whether or where Kapp Toscana rocks may occur. (i) In the eastern zone the Sassendalen Group rests on Tempelfjorden Group strata within the foldbelt as to the north. That is continuing the Treskelodden relationship to the SSE within the foldbelt. (ii) In the central zone relatively flatlying Sassendalen Group strata rest with sharp angular unconformity on deformed Precambrian to Early Paleozoic rocks. This zone has been referred to as the Hornsund High. (iii) In the west similarly flatlying strata rest with only minor discordance on similarly flatlying Billefjorden Group rocks. However this western zone did not escape Paleogene deformation because there are Klippen of relatively horizontal Mesozoic strata as illustrated in the Sorkapp Land map C13G (Winsnes et al. 1992). (iv) In Sorkappoya, the island south of Sorkapp Land Sassendalen Group strata are infolded in a steep syncline with Tempelfjorden Group rocks trending N W to N N W . If extended this fold belt would pass offshore west of Sorkapp Land as it parallels the West Spitsbergen Orogen. Zone (i) continues with that at Treskelen to the north with sections at Smalegga just south of Hornsund and at Austjokeltinden about 13 km south of Hornsund. Wilhelmoya Fm, c. 25 m at both localities De Geerdalen Fro, c. 40 m at Smelegga and 55 m at Ausjokeltinden Tschermakfjellet Fm( = Austjokelen Formation of Mork et al.) Sticky Keep Fm Vardebukta Fro. In zone (ii) two sections are available from Karentoppen and Kistefjellet

Kapp Toscana Gp, c. 60 m Wilhelmoya Fm at Kistefjellet, c. 35 m De Geerdalen Fin at Kistefjellet, c. 31 m Tschermakfjellet Fm at Kistefjellet, c. 16m Sassendalen Gp c. 100 m Botneheia Fm at Karentoppen, 65 m Kistefjellet 75 m Kistefjellet Fm (=Sticky Keep and part of Vardebukta) 50m at Karentoppen, 35 m at Kistefjellet. In zone (iii) No measured sections are recorded here. In zone (iv) in Sorkappoya the succession is upper strata lost to erosion Botneheia Fm, c. 60 m Sticky Keep Fro, c. 90 m Vardebukta Fro, c. 60 m Tempelfjorden Gp Kapp Starostin Fro.

4.4.8

Kongsfjorden

The coalfield at Ny-Alesund is described in Chapter 9. The Bottom Shale of Orvin (1934), beneath the coal-bearing Paleogene strata,

63

was correlated by Challinor (1967) with the Vardebukta Formation. This unit thins from 50 m at the SE of the coalfield to zero at the southwest which demonstrates the limit of Mesozoic strata of the Central Basin in that direction.

4.5

Biinsow Land Supergroup

Comprising Tempelfjorden, Gipsdalen and Billefjorden groups: Permian, Carboniferous, and latest Devonian. The cliff sections from Billefjorden through to Tempelfjorden provide excellent exposures of the whole Carboniferous through Permian succession (Fig. 4.10), and have become the type sections for central Spitsbergen, hence the Biinsow Land Supergroup. The sequence was deposited in the Billefjorden Trough, mainly situated to the east of the Billefjorden Fault zone, and an active basin from Tournaisian through Moscovian time. To the west of the fault zone lay the Nordfjorden Block/High, where sedimentary rocks of those ages are absent. Following Moscovian time, subsidence was regional and most formations are represented across both sides of the fault zone and throughout the central area. Early investigations on the succession focussed on the Billefjorden-Tempelfjorden region (Nathorst 1910). The first systematic description resulted from a measured study at the now classic Festningen section, located at the southern entrance to Isfjorden (Hoel & Orvin 1937, Fig. 4.1). Brief contemporary surveys were carried out and described by Frebold (1935) and Orvin (1940). In 1938 and from 1948 onwards many groups from Cambridge studied the exposures (for example: Gee, Harland & McWhae 1953; Forbes, Harland & Hughes 1958). Exploration by Amoseas (an industrial consortium, jointly with Cambridge University geologists in the 1960s and in consultation with Norsk Polarinstitutt, resulted in reclassification of the strata throughout Svalbard (Cutbill & Challinor 1965), using nomenclature in accordance with the N o r t h American Stratigraphic Code which was being widely adopted at that time. Several changes have been suggested since then, primarily to the Svenbreen and Nordenski61dbreen formations (Dallmann et al., SKS 1996). These and the scheme used here are shown in Fig. 4.11.

4.6

Tempelfjorden Group (Permian)

The Tempelfjorden Group in Spitsbergen comprises the Kapp Starostin Formation. It was defined by this and the Miseryfjellet Formation of Bjornoya.

4.6.1

Kapp Starostin Formation

The Kapp Starostin Formation is the main unit of the Tempelfjorden Group in central and western Spitsbergen. It consists of a thick siliceous sequence which is resistant to weathering, and hence is well exposed and a distinctive marker horizon throughout Spitsbergen, having softer Gipsdalen Group dolostones below and Triassic shales above. The type section is at Kapp Starostin (Festningen), Nordenski61d Land, where the formation is 380 m thick (Fig. 4.1). The formation mainly contains limestones, lutites, arenites and cherts, generally with sponge spicules. Sandstones are commonly cross-bedded, bioturbated and glauconite-bearing. The sequence is transgressive overall, with deposition occurring in a shallow shelf environment where shoals and reefs were present. An abundant fauna of brachiopods, bivalves, corals and others indicate a Kungurian-Ufimian age.

64

CHAPTER 4

Fig. 4.10. Geological map of Bansow Land showing the distribution of Permo-Carboniferous formations (Bfinsow Land Supergroup), adapted with permission from SKS proposals for Lithostratigraphical Nomenclature of the Upper Paleozoic rocks of SvaIbard, Part I (Dallmann et al. 1996, fig. 3d). White areas indicate fjords or (on land) supergroups younger (? Nordenski61d Land - mainly Mesozoic) or older Devonian (Liefdebay Supergroup) to the NW or pre-Devonian Hecla Hoek Complex to the NE. Place names are selected for their relevance to stratigraphic nomenclature in this classic area of north-central Spitsbergen. Those given by numbers are as follows: (1) Birger Johnsonfjellet; (2) Brucebyen; (3) Cadellfjellet; (4) Campbellryggen; (5) Carronelva; (6) Citadellet; (7) Ebbadalen; (8) Finlayfjellet; (9) Fortet; (10) Gerritbreen; (11) Gerritelva; (12) Gipshuken; (13) Hoelbreen; (14) H ultberget; (15) Minkinbreen; (16) M umien; (17) Odellfjellet; (18) Pyefjellet; (19) Pyramiden; (20) Sporehogda; (21) Svenbreen; (22) Templet; (23) Terrierfjellet; (24) Trikolorfjellet; (25) Triungen; (26) Tyrrellfjellet; (27) Wordiekammen. Definition: The formation was defined by Cutbill & Challinor (1965) and is the exact equivalent of the Brachiopod Cherts of Gee et al. (1953; Fig. 4.11). It is exposed along the west coast and extensively across northern Spitsbergen to Nordaustlandet. Small outcrops have been described from Barentsoya (Klubov 1965) and Edgeoya (Pchelina 1977). lsopachs for the formation (Cutbill & Challinor 1965) show that deposition was in the large Central Basin with thickest sedimentation in western Nordenski61d Land where up to 450 m are preserved. There appears to be a secondary centre of deposition in the Tempelfjorden area, which may, however, be due to differential pre-Triassic erosion. The formation thins rapidly onto the Hornsund High in the south. This was a positive feature during deposition and a site of pre-Triassic erosion. Southwest of the Hornsund High, Late Permian sediments are preserved in a somewhat separate basin. The top of the formation is a distinctive marker horizon, with the resistant siliceous deposits of the Hovtinden Member lying below soft shales of Early Triassic age. The base is also distinct, defined as a disconformity, overlying the less resistant gypsums, dolostones and calcretes of the Gipshuken Formation. Through many areas of Svalbard, the base is marked by a sandy bioclastic limestone, the Voringen Member, which rests with a sharp and erosive contact on the underlying Gipshuken Formation. A distinctive fauna of large thick-shelled spiriferid brachiopods gave this unit the name 'Spirifer Limestone'. It represents the transgression of a barrier sequence over the restricted marine platform and sabkha facies of the underlying group (Aga et al. 1986) and marks a clear change in environment (see below). Lithologies: The formation shows a variable development of tithofacies but in general four main lithologies are recognized: limestones, lutites,

arenites and cherts. Silicification of the limestones, shales and siltstones is characteristic and there is a continuous gradation into pure cherts, which are estimated to constitute about 50% of the rock. Indeed a distinctive feature of later Permian sediments is their high silica content and cherty rocks are the dominant lithology of the Tempelfjorden Group. About 50% of the cherts are of a massive type interbedded with shales. These consist of massive layers of dark grey or black, very hard rock, composed of sponge spicules, quartz grains and fossil fragments in a brown groundmass of authigenic silica. The sponge spicules may be calcified on diagenesis, and their axial canals are commonly filled with glauconite or silica. The brown colour of the chalcedony cement is probably due to the presence of carbonaceous matter. Finely divided hydromicas are also present. Finely crystalline cherts, consisting mainly of brown chalcedony with minor terrigenous quartz 'dust' (<0.03mm), hydromicas and carbonates, also occur, commonly containing a high proportion of glauconite in the form of rounded grains approximately 0.15 m m in diameter. Some beds are almost pure spiculite, consisting of closely packed and cemented light brown, chalcedonic sponge spicules. Much of the so-called massive chert is calcareous, suggesting that it may be diagenetic, replacing carbonate. Limestones form a marginal facies and make up about 25% of the formation. They occur in the northeast in the Hovtinden Member and in the north and south in the Svenskeega Member, while the basal Voringen Member is composed entirely of a white, brachiopod-bryozoan coquina. The limestones are usually calcarenites/biosparites with silica and calcite cement. They are invariably highly fossiliferous, with abundant silicified brachiopods and bryozoans. Chert bands and nodules also occur, which commonly show replacement structures of the original limestones and this

THE CENTRAL BASIN

Gee, Harland & McWhae (1953) Forbes, Harland & Hughes (1958) co

Cutbill & Challinor (1965) Holliday & Cutbill (1972)

Upper

z ~

Hovtinden Mbr

Lower

n" ~

Svenskeegga Mbr

Limestone A

~

Voringen Mbr

..z

,,z

m

UPPER GYPSIFEROUS SERIES

KAPP STAROSTIN FM

~; n. ,,c_ F-,,"

SKS Recommendations (Dallmann et el., 1996) adopted here

Dallmann (1993) McCann & Dallmann (1995)

Johannessen & Steel (1992)

Middle

"'

65

,,2 KAPP STAROSTIN

FM

~o

~-Z

Ho~indeo Mbr

~

nLU~ w w--.

n" ~ ~

I--LE

nO-

I--LC

~

GIPSHUKEN FM

GIPSHUKEN F M

GIPSHUKEN F M

~ 3~ n. u.I--.

Svenskeegga Mbr Veringen Mbr GIPSHUKEN F M

o Zn

Limestone B Upper

z

~ u,~

Middle

P3

~ .~ --~

L. . . .

~VLL = (,9 ~

Black Crag

z QO w J'

z

z

~ uJ

Cadellf]ellet Mbr

~

z

ca ._j ~7

~

m

_~

70

70

Trikolor~elIet

Mbr O<

~ ~VU. =

Cadellfjeltet Mbr

i

z

I Teltf]ellet

I

Odellf]ellet Mbr Tdkolorf]eUetMbr "~

~ u.I

I Sandstone Mbr

Ebbaelva Mbr

I

BILLEFJORDEN SANDSTONES (CULM)

z Cadellfjellet Mbr

Tyrrellf]ellet Mbr

u~z ~ ~

Z

J

Cadellf]ellet Mbr

~: D

~ Fortet Mbr AnsuivikaMbr Carronelva Mbr

~ ~ _~ ~ ,,~ :; ,7?

Ferret Mbr Terrie~ellet Mbr Carronelva Mbr

~

OdellfJelletMbr

z

:~

,~ ~ ~ uJ

Trikolo~ellet Mbr

a< ~ ~

~ O

(~

z QQs m~'_J

Trikolorf]ellet Mbr

Ebbaelva Mbr

:~z

Hultberget Mbr ww~ > ~ ~=

Tyrretl~ellet Mbr

Mbr

Ebbaelva I Gerritelva Mbr

~" L~ ~ ~ ~ 3; ~

Minkinfjellet Mbr

Minkinf]ellet Mbr

LOWER GYPSIFEROUS SERIES

Tyrrell~ellet Mbr

z

7~

Passage Beds

(=Pyramiden Conglomerate)

TyrerrelfJellet Mbr

Hultberget Mbr

Sporhogda Mbr

Cl wZ 8 ~ m~ ~J ~>m

u~ z >" w

Hoelbreen Mbr

"~' ~'

~ ~ LL

Triungen Mbr

Sporhogda Mbr

HORBYEBREEN FM

w w ..~

Sporhegda Mbr

~ O ~ ~,

Hultberget Mbr

~ z ~.~.m un~- tu nm~

Hoetbreen Mbr Triungen Mbr

HULTBERGET FM

~

MUMIEN FM

O

u~z

~

>'ILl mwmu_

~

~ =

Birger Johnsont]ellet Mbr Sporhegda Mbr Heelbreen Mbr

z O

~_ Triungen Mbr

,

Fig. 4.11. Summary of the stratigraphic schemes for Central Spitsbergen since 1950. For earlier schemes see review in Cutbill & Challinor (1965).

process has resulted in the formation of massive calcareous cherts. These are bituminous on Edgeoya (Pchelina 1977) Fine- to coarse-grained quartz sandstones are less important (about 18% of the formation). They occur in a widespread littoral facies in the Hovtinden Member and also in the Svenskeega Member. They contain cross-bedding and are commonly calcareous and bioclastic, with calcite or silica cement and are usually greenish coloured owing to the presence of appreciable quantities of glauconite (up to 3%). Porosity is generally low. These bioclastic sands, common in the middle of the group over eastern areas of Spitsbergen, can be distinguished from the major 60 m thick clastic wedge which is only seen in northwestern areas uppermost in this formation. These latter sandstones are immature and commonly contain 10-30% glauconite. Heavy bioturbation has destroyed primary bedding features. Shales and siltstones showing little or no silicification make up only 7% of the formation, occurring as thin interbeds between the limestones on the margins of the basin. They are commonly calcareous and pass laterally into limestones or arenites in the upper part of the formation. Silicification generally increases towards the centre of the basin with a gradation into cherts. Division: Cutbill & Challinor (1965) defined three members within the formation in the main Triassic outcrop of the Central Basin (Fig. 4.11): the Hovtinden Member; the Svenskeega Member; and the Voringen Member. Russian workers distinguished a separate, arenaceous 'Selander Suite' (Selanderneset Mbr), lying unconfomably above the 'Starostin Suite' in the northern sections (Burov et el. 1965). The Selander Suite is probably equivalent to the sandstone-limestone facies of the Hovtinden Member (see below), which pass laterally into shales, siltstones and cherts in Oscar II Land.

Hovtinden Mbr. This member, 203m thick in the Festningen section is present from Hornsund to Nordaustlandet though it is made up of a variety of complexly interdigitating facies. In northeastern and southern outcrops of Spitsbergen, this member lies directly on the Gipshuken Formation, the Voringen Member facies being absent. It is transgressive in southern Spitsbergen, overlapping progressively older rocks southwards towards the Hornsund High. In general, it consists of a central basinal facies of finely crystalline cherts, shales and siltstones, with arenaceous rocks and carbonates to north and south at the basin margins. The shale-chert facies in some sections is split by a limestone horizon and in north and central Spitsbergen, cross-bedded sandstones and arenaceous cherts also appear.

Svenskeegga Mbr. This member, 156m thick in the Festningen section, shows a similar facies pattern. The top is marked by the Jemtlandryggen Beds, made up of a yellow-weathering silicified limestone containing a prolific brachiopod-bryozoan fauna which is a distinctive marker horizon. Silicification locally results in true chert. There is also a sandstone or lutite interbed. Below are the Tornefjellet Beds, cherts with rare lutites, occurring in the central part of the Isfjorden Basin and Nordaustlandet. They pass both laterally and vertically into a more or less silicified limestone facies known as the Garwoodtoppen Beds which are widely developed in northern and southern Spitsbergen. The limestones are dark grey, weathering yellow, and commonly cyclically interbedded with lutites. A 10m thick breccia is present 20 m above the top of the Voringen Member of Bjorndalen (Sassenfjorden). It consists of nodular orange cherts which are commonly bioturbated and form lenticular blocks a few metres across. Bedding varies from horizontal to contorted and overturned. The basal contact of the breccia is erosive and marked by a shaly band. Voringen Mbr. This consists of 22-39 m of distinctive, light-coloured, coarse fragmental limestone with silicified brachiopods and bryozoans. It occurs at the base of the Kapp Starostin Formation from Bellsund to St Jonsfjorden and Nordaustlandet but is absent south of Bellsund and from most of Oscar II Land and is replaced by calcareous sandstones in Ny Friesland and southwest Nordaustlandet. It is the Spirifer Limestone and Brachiopod Limestone of previous authors and 'Limestone A ' of Gee et el. (1953) and is a useful marker horizon. Coal fragments are present in the lower part south of Sassenfjorden and in Nordaustlandet (Lauritzen 1981); this is probably an indication of erosion of the top of the Gipshuken Formation, as coaly shales are present in the topmost Gipshuken Formation in Nordaustlandet. The basal contact is erosive in Bellsund also, with clasts of micrite from the underlying Gipshuken Formation, which is extensively bored. Elsewhere on Svalbard, the contact is poorly exposed, owing to the susceptibility of the Gipshuken Formation to erosion, but there is further evidence for a disconlbrmity in the phosphatic nodule beds found at the base of the formation on the south side of Sassenfjorden. These may have been eroded from the underlying strata. Some were associated with glauconitic sands, a combination characteristic of episodes of slow sedimentation/non-deposition.

PNaeontology and age: The formation contains an abundant fauna, predominantly of silicified brachiopods, but also of bryozoans, bivalves, corals, sponge spicules, echinoderms, gastropods and foraminifers. Trace fossils abound, with Zoophycos, Teichichnus and Chondrites.

66

CHAPTER 4

Szaniawski & Malkowski (1979) distinguished two time-equivalent fossil associations which represent different depths: the bioclastic limestone facies of near-shore, shallow water, high energy thicker-shelled species and an offshore, low-energy, deeper water fauna dominated by sponges, with more fragile brachiopods and bryozoans, which occurs in the siliceous rocks associated with in-situ glauconite and pyrite. The brachiopod fauna is broadly comparable with the later Early Permian and Late Permian assemblages of Russia (Tschernyschew 1898, 1902). However, many of the species have long time ranges and show considerable intraspecific variation which has caused confusion over correlation. Biernat & Birkenmajer (1981) found that at the base of the Kapp Starostin Formation in Torell Land, two brachiopod species were the same as those in SakmarianEarly Kungurian rocks of Inner Isfjorden. Many species are closely related to the Artinskian or Kungurian species of the Soviet Union, but several genera characteristic of Late Permian also occur (Gobbett 1963). Ustritskiy (1962) and Burov et al. (1965) distinguished two separate faunas, both belonging to the Ufimian stage, in the 'Starostin Suite' (= Svenskeega/Voringen Members) and 'Selander Suite' (= Hovtinden Member), the latter being distinguishedby the presence of Cancrinelloides and Sowerbyna. These assemblages have not yet been recognized throughout Spitsbergen. A Kungurian age has been confirmed for the lowerpart of the formation (Nysaether 1977; Ustritskiy 1979) and a Ufimian age is indicated by the foraminifera for the small Permian inliers of Edgeoya, which are of the glauconitic chert facies (Pchelina 1977). The upper part contains brachiopods which extend into the Kazanian stage (Ustritskiy 1979) and Ustritskiy assigned the 'Starostin' (= the Voringen and Svenskeegga Members) and 'Selander' (= the Hovtinden Member) 'Formations' to Boreal stages (Paykhoyian and Early Novozeml'ian) which correlate with the Kungurian-Ufimian and Kazanian-?basal Tatarian respectively. Conodont assemblages also confirm a Kungurian-Ufimian age as they correspond stratigraphically to the Late Leonardian/Early Roadian of the USA (Szaniawskij & Malkowski 1979). As the formation is transgressive, lithological boundaries must be diachronous until open-sea cherty facies occur everywhere, i.e. at the top of the formation (Malkowski 1982). There is a stratigraphic gap in the Hornsund region, where the Voringen and Svenskeegga Members of the Isfjorden area are absent.

4.7

Gipsdalen Group (Permian-Carboniferous)

Cutbill & Challinor (1965) originally defined the Gipsdalen Group within the Billefjorden area to contain the Gipshuken, Nordenski61dbreen and Ebbadalen formations. However, the Nordenski61dbreen F m has been replaced by the Wordiekammen and Minkinfjellet formations. Hence now the group comprises the Gipshuken, Wordiekammen, Minkinfjellet and Ebbadalen formations. These four formations are (Dallmann 1996 SKS) combined in two subgroups thus: Gipsdalen Group (Cutbill & Challinor, 1965) Dickson Land Subgroup (SKS) Gipshuken Formation (Cutbill & Challinor, 1965) Wordiekammen Formation (Gee et al. 1952, SKS) Campbellryggen Subgroup (Forbes, Harland & Hughes 1958, SKS) Minkinfjellet Formation (Cutbill & Challinor 1965) Ebbadalen Formation (Cutbill & Challinor 1965) The upper subgroup extends from Btinsow Land to the west across Dickson Land. The lower one is confined approximately to the Billefjorden Trough. As elsewhere in Svalbard, the base of the group is marked by the appearance of red-beds; these pass upwards through terrestrial and marine restricted-basin deposits into platform carbonate sequences with increasing quantities of evaporites. Deposition of the group and the underlying Billefjorden Group occurred initially within distinct, small basins defined by faults (Fig. 4.12). Later deposits, however, blanketed the entire region. Each formation is described below.

4.7.1 Gipshuken Formation (Dickson Land Subgroup) Present across much of western and central Spitsbergen, the Gipshuken Formation is 150-250m thick, consisting mainly of carbonates and evaporites with minor quantities of sandstone.

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Fig. 4.12. Schematic west-east stratigraphic profile showing lateral variations and structural controls on Carboniferous stratigraphy. Simplified, and modified with later SKS nomenclature, from Cutbill & Challinor (1965) with permission of Cambridge University Press.

THE CENTRAL BASIN R h y t h m i c d e p o s i t i o n a l sequences o f l i m e s t o n e / d o l o m i t e a n d g y p s u m / a n h y d r i t e are c o m m o n , especially in central exposures. T h e f o r m a t i o n was d e p o s i t e d in w a r m , shallow seas a n d tidal flats w i t h restricted c i r c u l a t i o n t h a t allowed high salinity to develop. In general, the evaporites, w h i c h represent arid l a g o o n a l , tidal flat a n d s u p r a - t i d a l s a b k h a deposits, are m a i n l y f o u n d in central Spitsbergen. E a s t w a r d s they are replaced by limestones a n d d o l o m i t e s . Fossils are scarce, b u t those t h a t are p r e s e n t indicate an A r t i n s k i a n age. Definition: These strata were included in the Cyathophyllum Limestone of early authors (Nathorst 1910), but were distinguished as a separate unit in the Billefjorden region by Gee et al. (1953), whose upper Gypsiferous Series is an exact equivalent. The formation was defined by Cutbill & Challinor (1965) in Billefjorden, where the formation is 210 m thick. Lauritzen (1981) proposed a hypostratotype for the formation at Trollfuglfjella on Dicksonfjorden, where the formation is exceptionally well exposed. It is thickest in western Isfjorden (up to 350 m), but over much of the outcrop, it is between 150 and 2 5 1 m . It thins northwards, nearer the Northern Block and southwards towards the Hornsund High (about 70 m at Drevbreen in Torell Land). in the Hornsund area it is absent, where the Kapp Starostin Formation lies disconformably on the Carboniferous Treskelodden Beds, which were formerly correlated with the Gipshuken Formation (Cutbill & Challinor 1965). The present outcrop of the formation is largely confined to two belts. Along the west coast of Spitsbergen, outcrop is sporadic and largely controlled by the structure of the West Spitsbergen Orogen. The strata in central Spitsbergen are mainly flat-lying and relatively well exposed. The formation also crops out in eastern Ny Friesland and Nordaustlandet, bordering Hinlopenstretet, and to the south on Bjornoya. It is present beneath the younger strata of central Spitsbergen. The upper boundary of the Gipshuken Formation is mapped at the base of the distinctive siliceous deposits of the Kapp Starostin Formation. Some erosion of the top of the Gipshuken Formation took place before deposition of the Kapp Starostin Formation in marginal areas, hence its absence in the south. The base of the Kapp Starostin Formation is a marker recognized throughout Spitsbergen. The lower boundary is transitional with the underlying Wordiekammen Formation, where the formation is preserved from pre-Kungurian erosion. The base is therefore defined by the appearance of gypsum, where present, or by the widespread and distinctive Kloten Breccia Member. Where both are absent, the top of the underlying Tyrrellfjellet Member is marked by the distinctive cliff-forming 'Limestone B' (Finlayfjellet Beds). Lithologies: The formation is a major regressive sequence characterised by highly variable lithologies, dominated by carbonates and evaporites, of which approximately 60% are carbonates, 30% gypsum and 10% arenites. In the central part of the Isfjorden Basin, rhythmic deposition of dolostone/limestone and gypsum/anhydrite continued throughout the formation. The central zone of sulphate deposition is surrounded by a broad zone in which only the dolomite/limestone part of the evaporite cycle was deposited. These rocks consist predominantly of algal-laminated, locally gypsiferous, silt-textured dolostone (about 35% of the formation) formed by the trapping of lime-mud by mucilagenous green algae. Thin interbeds of silt-textured limestone occur locally. Some of the dolostones within the anhydrite zones of the lower part of the sequence in Torell Land are rich in quartz sand. Dolomitised ooids and pelloids occur with micritic dolomites in Dickson Land and Torell Land, where anhydrite nodules and cement are common in the anhydritic zones of the lower part. The gypsum/anhydrite horizons are locally massive and form relatively thick, continuous beds parallel or sub-parallel to the bedding. Elsewhere, the sulphate is laminated or finely interbanded with dolostone or rare limestone. It may also occur as nodules up to 1 m in diameter, separate crystals or infillings of cracks, fissures and stylolites (Lauritzen 1977). The gypsiferous deposits pass laterally into continuous dolostone. Laminated shales occur in units up to 2 m thick between the anhydrite beds. About 30 rhythms with anhydrite have been recognised in the Dicksonfjorden area by Lauritzen (1981), varying in thickness from 0.6 to about 9.5m. Each rhythm starts with a carbonate unit, which may contain ripples and cross-bedding or oolitic beds, followed by carbonates with anhydrite nodules, ending with chicken-wire anhydrite and commonly terminated upwards by a sharp, erosive contact with the base of the next cycle. Karstic surfaces have been observed in the anhydrite (Lauritzen 1983). Dolomitization is almost complete in this cyclic succession and is thought to be early diagenetic. Locally, in west Spitsbergen, dedolomitisa-

67

tion is well developed, with corroded clasts of yellow-weathering dolomicrite in a grey calcite matrix passing into uniformly grey calcitised rock. In the lower part of the formation, is a widespread group of carbonate breccias up to 30 m thick which make up about 13% of the formation. Two distinct types can be recognized- a hard, massive variety and a soft, porous, cellular type. The massive breccia is of rather limited occurrence in the northwest of the outcrop area, where it forms a resistant marker horizon. It consists of a complex of grey, laminated, silt-textured dolostone or limestone blocks, up to several metres in diameter, in a dolostone or limestone matrix. The dolostone weathers yellow and the limestone grey, but the unit is very hard and individual fragments are difficult to identify on unweathered surfaces. The fragments commonly show contorted lamination, indicating slumping prior to brecciation. In some cases dolomite is seen replacing calcite across fragment boundaries, whilst others show a sharp contact. Patches of dolomite crystals give a mottled effect in places. The cellular breccia has a wider distribution, and consists of brecciated silttextured limestone and dolostone. The interstices between the individual fragments may be filled by dolomite or calcite cement and calcite veining commonly gives a honeycomb structure. In places cement may be completely or partially absent, giving the rock a high porosity and permeability. Its cellular appearance is due to the variable weathering properties of calcite and dolomite. The breccias appear to pass laterally by way of sandy limestones and dolomites into arenites. In Bellsund, minor breccias are present in the upper parts of the Gipshuken Formation, where laminated dolomicrites occur with thin sandy interbeds, the relationships of which suggest that brecciation occurred prior to full lithification of the sand. Fossiliferous limestones, consisting of calcilutite and calcarenite, interdigitate with the dolostones in the upper part of the formation, making up about 8% of the sequence. In Torell Land they form the upper third of the formation and show a general increase in coarseness towards the top from dark grey micrites to grey-black biosparites. The darkening in the biosparites probably reflects increasing contents of organic matter. Fine laminations and small-scale ripple-marks and convolute bedding have been recorded (Nysaether 1977). Fossils are not common, but brachiopods do occur. Division: Gipshuken Formation deposits show a variation in facies, but only the distinctive breccias have been defined as members where they appear (see below). In Spitsbergen, in a general way, the sequence can be divided into: (5) The upper dolostone-limestone zone consisting of interdigitating dolostones and limestones. In Torell Land there is only limestone. (4) The upper gypsum zone comprising the evaporite deposits occurring in the centre of the basin, particularly on the west coast. North of Isfjorden, there are only nodules and thin beds of evaporites in a predominantly dolomicrite sequence. (3) The Kloten Breccia Mbr (Cutbill & Challinor 1965) containing the various types of limestone/dolostone breccia described above. It forms a conspicuous marker horizon 88 m thick in the type section at Scheteligfjellet in the northeast of Spitsbergen and similar breccias occur eastwards to Tempelfjorden and also in Ny Friesland and Nordaustlandet. The latter outcrop was named the Zeipelodden Mbr by Lauritzen (1981). (2) The lower dolostone zone consisting of dolostones transitional between the Kloten Breccia Member and the lower gypsum zone below. It is only recognisable in the area of northwest Spitsbergen (Colletthogda) where true brecciation has not taken place, but contortion and slumping has occurred. (1) The lower gypsum zone consisting of the evaporites occurring in the lower part of the formation, mainly in the Billefjorden and Nordfjorden regions. The zone is rather restricted in western Spitsbergen. The Zeipelodden Mbr is 8 m thick and contains a mixture of lithologies, limestone breccias occurring together with finely laminated algal limestones, one passing into the other. Irregularly bedded horizons are weathered into distinctive caverns up to I m high. Hemispheroids of algal build-ups 2-3 m across, algal mats and crusts have been identified. A mixture of white chert and calcite is found within some of the hollows of the rock. The rocks are highly porous and dominantly calcitic, with clear evidence of dedolomitisation. This unit is, however, best considered in Chapter 5. Palaeontology and age: The bulk of the Gipshuken Formation appears to be unfossiliferous. Dolomitization has destroyed much of the evidence of fauna but algal lamination is extremely common in the micrites, caused by mucilaginous blue-green algae (Lauritzen 1981). Another prominent feature observed in thin-sections from the upper part of the succession (Lauritzen 1981) is Microeodium which has been described from palaeosols (Klappa 1978).

68

CHAPTER 4

Fossiliferous beds do occur in various places. Gastropods, especially bellerophontids, and bivalves have been recorded by Lauritzen in the Dicksonfjorden area as well as a little bioturbation. In addition, CSE 1985 found echinoids, crinoids and bryozoa in Nordaustlandet. A few productid brachiopods have been found in the upper part of the formation in Nordaustlandet, Kopernikusfjellet and at Trygghamna which indicate a correlation with the Hambergfjellet Formation of Bjornoya; (the latter contains Artinskian fusulinids). Cancrinella koninkiana which was found in the Gipshuken Formation by Ustritskiy (Burov et al. 1965) is typical of the Artinskian stage and Sossipatrova (1967) discovered the Frondieularia multicamerata assemblage in the middle of the formation in Bunsow Land and correlated it with the Artinskian deposits of the Urals and north Timan.

4.7.2

Wordiekammen Formation (Diekson Land Subgroup)

T h e W o r d i e k a m m e n L i m e s t o n e o f G e e et al. (1953) was redefined (SKS, D a l l m a n n et al. 1996) to take in the u p p e r t w o m e m b e r s (Tyrrellfjellet a n d Cadellfjellet) o f the N o r d e n s k i t l d b r e e n F o r m a tion o f Cutbill & C h a l l i n o r (1965). W i t h the G i p s h u k e n F o r m a t i o n it c o m p r i s e s the D i c k s o n L a n d S u b g r o u p , the characteristic o f w h i c h is a relatively u n i f o r m s p r e a d o f facies t h r o u g h o u t m o s t o f Spitsbergen. In this respect the D i c k s o n L a n d S u b g r o u p contrasts w i t h the u n d e r l y i n g C a m p b e l l r y g g e n S u b g r o u p w h i c h is s e p a r a t e d into distinct basins.

Tyrrellfjellet Member is a widely d e v e l o p e d c a r b o n a t e sequence o f Early P e r m i a n ( A s s e l i a n - S a k m a r i a n ) age, o c c u r r i n g at the t o p o f the o t h e r w i s e C a r b o n i f e r o u s W o r d i e k a m m e n F o r m a t i o n . T h e type section is at Tyrrellfjellet, Billefjorden, w h e r e it is 1 6 0 m thick; elsewhere its thickness is variable f r o m 1 0 0 - 1 6 0 m . It c o n t a i n s limestone, d o l o s t o n e a n d arenites, with local gypsiferous units, widely d e v e l o p e d cherts, a n d P a l e o a p l y s i n a b i o h e r m a l m o u n d s . T h e f o r m a t i o n was d e p o s i t e d in l a g o o n a l a n d o p e n m a r i n e basin e n v i r o n m e n t s . It is highly fossiliferous with a varied fauna.

Definition: The member was defined by Cutbill & Challinor (1965). These limestones form the middle part of the Cyathophyllum Limestone of early workers (Nathorst, 1910); they are equivalent to the Mid- and Upper Wordiekammen Limestones described by Gee, Harland & McWhae (1953) in the Billefjorden area. It is thickest in the west (243 m at Orustdalen); over most of Spitsbergen it is 100 150m thick. The formation thickens slightly across the Billefjorden Trough, and thins slowly to the east across Ny Friesland. In Nordaustlandet it is replaced by the similar Idunfjellet Member and in southern Spitsbergen by the Treskelodden and Reinodden formations. The formation lies conformably beneath the dolostones and evaporites of the Gipshuken Formation. The highest beds of the Tyrrellfjellet Formation are transitional, containing dolostones, but the boundary can be mapped by the distinctive facies attributed to the Gipshuken Formation (see above) and by the occurrence of the distinctive cliff-forming 'Limestone B' at the top in the Billefjorden area (see below). The lower boundary of the formation represents a widespread marine transgression in Spitsbergen, which approximates the initial Permian boundary. In the west and south, the formation rests on various Carboniferous horizons, but throughout the northern outcrop it overlies Late Carboniferous shelf carbonates. However, near the base, the Brucebyen Beds form a marker horizon which can be recognised over much of the area. A thin sandy horizon, locally conglomeratic, occurs a few metres below the Brucebyen Beds which marks the basal disconformity or non-sequence in this area and can be recognized when outcrop is sufficiently good. Lithologies: The Tyrrellfjellet Member is made up of limestones (c. 85%), dolomites (c. 5%) and arenites (c. 10%). Fossiliferous relatively shallow-water shelf limestones, consisting of calc-lutite and calcarenite with subordinate dolostone occur over large areas of Spitsbergen in the lower part of the formation. They contain abundant corals, brachiopods and fusulinids. Similar shelf carbonates occur in the upper part of the formation, but are more commonly dolomitic, much less fossiliferous and pass laterally into dolostones. Close examination of the sequence has revealed the presence in the lower part of the sequence of biohermal structures (Skaug et al. 1982). The bioherm horizons are separated by fusulinid-rich wackestones and packstones which are dolomitized or bituminous as in the Brucebyen Beds (see below), which is a bituminous fusuline coquina.

Intraformational conglomerates occur locally above the bioherms, as do desiccation cracks. The bioherms are up to 2500 m 2 in area and their original calcite mudstone is dolomitized to some extent. Examination of thin sections (CSE 1985) revealed two types of dolostones, fine and coarse. The finer dolomicrite variety suggests early 'penecontemporaneous' replacement, possibly by evaporitively modified brines, since these solutions tend to have a considerable potential to dolomitize and hence are likely to alter calcium carbonate very rapidly, producing fine-grained dolomite; the presence of nodular gypsum locally provides evidence of an evaporative environment. The coarse dolostone is probably late-diagenetic as high-magnesium calcite crinoid and echinoid fragments, which should have been preferentially altered have not been dolomitized, suggesting that they were stabilized to low-magnesium calcite prior to replacement. All bioherms show good primary growth-framework porosity which is enhanced by secondary porosity associated with the dissolution of skeletal grains during dolomitization. In places porosity has been reduced by the crystallization of gypsum in pore spaces. Dolostones occur mainly in the upper part of the formation and largely in the northwestern outcrop area. They consist of very thinly bedded or laminated silt-textured dolostones with rare limestones, locally gypsiferous, and pass laterally into shelf carbonates. In the dolostone interbeds of the lower part, pseudomorphs after ?evaporite crystals have been noted, in places filled by length-slow chalcedony, calcite or dolomite; others are darkstained with a high kerogen and pyrite concentration (Skaug et al. 1982). Chert, generally occurring as nodules or rarely as bands, is locally widely developed, though not on the scale of the Tempelfjorden Group. The nodules, preserving bioclastic remains, are found within secondary dolostones in which sedimentary fabric has otherwise been destroyed. Sedimentary laminae are commonly deformed around the chert nodules, pointing to early diagenetic silicification, prior to complete compaction. Stylolites, which skirt around the nodules, support the latter observation. Calcareous sandstones, locally silty, are found as thin layers or lenses in the shelf limestones. They occur in the north, and in Ny Friesland where they are fine to medium-grained and interbedded with limestones. Crossbedding indicates currents from the southeast. On the Hornsund High, the limestones pass laterally into the commonly calcareous sandstones of the Hyrnefjellet Formation (Chapter 10). At the base of the formation is a thin sandstone horizon with a locally developed basal conglomerate. Division: The upper part consists of carbonates, commonly dolomitic, occurring throughout much of northern and eastern Spitsbergen. To the east and north they pass laterally into calcareous sandstones, and in the northwest into the dolomitic Ki~rfjellet Beds. Defined by Cutbill & Challinor (1965), the Kiaerfjellet Beds are thinly-bedded soft dolostones 96m thick developed at the top of the Tyrrellfjellet Member in the northwest of Spitsbergen. In eastern Svalbard and in the type section on Tyrrellfjellet, there is a cliff-forming calc-lutite forming the upper part of the member named 'Limestone B' by Gee et al. (1953, fig. 4.7) and Finlayfjellet Bed (SKS, Dallmann et al. 1996). The limestone is a 38 m thick cliff-forming micrite which makes a useful marker at the top of the Tyrrellfjellet Member in Btinsow Land. The lower part of the Tyrrellfjellet Member on Spitsbergen consists of fusuline limestones, locally biohermal, underlain by the bituminous micrudite Brncebyen Beds which are themselves underlain by up to 10m of dolostone, again locally biohermal, then a thin basal sandstone horizon with a locally developed conglomerate. The Brucebyen Beds, (Cutbill & Challinor 1965), consist of 2-20 m of distinct dark grey bituminous fusuline limestone coquina or biomicrite with a gradational top and base, 5-10m above the base of the Tyrrellfjellet Member. The fusulinids lack wall structures and their body chambers are infilled with dolomite. This is an excellent marker horizon over large areas of Spitsbergen. These beds occur within or below the palaeoaplysinid biohermal structures. In some areas eg. Gerardfjella, the carbonates are completely replaced by dolomicrite; nodular gypsum is also present here. Palaeontology and age: The formation is highly fossiliferous, with brachiopods, corals, bryozoans, echinoderms, bivalves, gastropods, sponges and foraminifera, of which fusulinids are particularly important as zone fossils where they occur, which is in the lower part only. Plant remains including algae, Microcodium and rootlets are also found. Skaug et al. (1982) described localised bioherms with Palaeoaplysina which are developed over the Billefjorden Fault Zone and elsewhere. There may be an algal contribution to the development of these structures. They are generally discoid and made up of subparallel to undulating plates up to 40 cm across which

THE CENTRAL BASIN may be closely packed or may enclose and bind pockets of bioclastic mudstone or wackestone containing all the above-mentioned fossils. They consist of small isolated dome structures up to 6 m high, tabular units up to 15m high, or offlapping sequences with one bioherm draping over the adjacent one to form structures up to 2500 m 2 in area. Their basal surfaces are sharp and usually planar to slightly undulating; most tops are sharply defined but some are gradational to overlying bedded carbonates. Studies of the abundant faunas found in the Tyrrellfjellet Member limestones by Forbes et al. (1958), Forbes (1960), Gobbett (1964), Cutbill & Challinor (1965) and Cutbill (1968) indicate an Early Permian age for these rocks. Gobbett distinguished two distinct brachiopod faunas in the Gipsdalen Group. The younger fauna, found in both the Tyrrellfjellet Member and also the Hambergfjellet Member on Bjornoya indicates a correlation with the Early Permian (Asselian/Sakmarian) faunas of Russia. Studies of fusulinids (Ross 1965; Cutbill & Challinor 1965) are in agreement with these ages. The lower part of the Tyrrellfjellet Member contains Asselian species of the Schwagerina anderssoni zone which compares with the Lower Wolfcampian fauna of Ross (1963) in North America. A poorly known assemblage from the middle of the formation belongs to the Monodiexodina zone which compares with the Early Sakmarian faunas of the Urals and Upper Wolfcampian faunas of North America (Ross 1963). The small foraminifers have received less study and stratigraphic conclusions based on them are less certain. Sosipatrova (1967) described a foraminiferal assemblage from the Tyrrellfjellet Member which helps to confirm the Asselia~Sakmarian age since Protonodosaria rauserae and Nodosaria parva are foraminifers diagnostic of the Boreal Sezymian stage (Asselian-Sakmarian). The Brucebyen Beds have a nearly identical fauna to the lower fusulinid-rich limestone within the palaeoaplysinid biohermal dolomites of the Kapp Dun6r Formation of Bjornoya.

Cadellfjellet, Kapitol and Morebreen Members.

The Cadellfjellet

M e m b e r , with equivalent Kapitol and Morebreen m e m b e r s to the west, consists o f a sequence o f late C a r b o n i f e r o u s limestones (locally dolomitic), occurring widely across Oscar II L a n d , James I Land, D i c k s o n L a n d and Btinsow Land. It reaches 200 m thickness in the Billefjorden area. The c a r b o n a t e s locally c o n t a i n gypsiferous layers and chert nodules. C a l c a r e o u s sandstones a n d s a n d y limestones f o r m a m i n o r p a r t o f the sequence. T h e f o r m a t i o n represents a stable m a r i n e shelf e n v i r o n m e n t , with sabkas present locally in coastal areas. F a u n a are sparse, but fusulinids suggest a late C a r b o n i f e r o u s ( K a s i m o v i a n - G z e l i a n ) age, possibly extending back to M o s c o v i a n .

Definition: Below the Tyrrellfjellet Member in central and western Spitsbergen lies a sequence of mainly limestones and dolostones. They are thickest in the Billefjorden Trough, where the type section lies; and thin westwards onto the Nordfjorden Block (the Kapitol Member), and then thicken again slightly into the St Jonsfjorden Trough in Oscar II Land (the Morebreen Member). The third is described in Chapter 9; the first two are described below. To the east in Ny Friesland, it is much thinner (40 m) and more arenaceous (see Chapter 7). The Cadellfjellet Formation is the lowest unit that can be identified across the Nordfjorden Block; below it deposits are restricted to the isolated basins of the St. Jonsfjorden and Billefjorden troughs. The Cadellfjellet strata were included in the Cyathophyllum Limestone of early workers and are equivalent to all but the uppermost part of the Lower Wordiekammen Limestones of Forbes, Harland & Hughes (1958). The unit was defined as a member within the Billefjorden area only, by Cutbill & Challinor (1965), equivalent to and laterally continuous with the Kapitol Member. (Nordfjorden area) and Morebreen Member. The top of the Cadellfjellet Member is marked by the widespread disconformity at the base of the Permian Tyrretlfjellet Member, which can be difficult to recognise in the carbonate sequence of this region. However, there is a thin, sandy, locally conglomeratic horizon at the bottom of the Tyrrellfjellet Member, and a few metres below, the distinctive bituminous fusulinid limestone coquina of the Brucebyen Beds In the Billefjorden Trough, the lower boundary is taken at the base of a black limestone horizon known as the 'Black Crag' (see below). Everywhere, the base is also defined by the appearance of Waeringella usvae zone fusulinids. The Kapitol Member is only about 50m thick thinning westwards across the East Dickson Land Axis from the 200m Cadellfjellet Member east of the Billefjorden Fault Zone.

69

Over the Nordfjorden Block, the Kapitol Member replaces the Cadellfjellet Member. The lower boundary is a strongly developed unconformity, below which Devonian sandstones occur. To the west of the Billefjorden Fault zone at Kapitol (type section of the member), the Cadellfjellet Member passes almost entirely into carbonates with very little horizontal or vertical variation. Limestones, mainly biomicrites and biosparites, form 70% of the sequence there. They are rather pure, grey and buff-weathering, with a high biogenic constituent. They commonly have a siliceous cement and horizons with abundant chert nodules occur. The remainder of the sequence is formed by primary dolomite as in the Mathewbreen Beds, which are largely uninterrupted in the east of the area but are interbedded with the limestones in the west. The Morebreen Mbr further west in the St Johnsfjorden Trough is thicker but not so easy to distinguish from the rest of the Wordiekammen Formation. It is described in Chapter 9.

Litbologies: The type section of the member is on Cadellfjellet, where it is thickest. There it consists predominantly (95%) of limestones, locally dolomitic, and rare gypsiferous layers. The limestones are grey, mainly massive micrites, becoming coarser-grained to the east. Calcareous sandstones and sandy limestones constitute the remaining 5% of the sequence. In the northeast (Ny Friesland), they occur in the upper part of the formation, commonly interbedded with gypsum layers and sedimentary breccias. In places, the lower 10-20 m of the basal limestones are brecciated. This was originally thought to be a result of collapse, following solution of evaporites in the underlying Minkinfjellet Formation (McWhae 1953). However, small-scale thrusts have also been observed forming an imbricated structure in the underlying beds, and suggesting at least a tectonic component. In southeast James I Land there is a thin conglomerate at the basal unconformity (Bates & Schwarzacher 1958). The clasts are generally small (5-10mm) and consist mainly of Devonian quartz sandstones and older quartzites in a reddish sandy matrix. In exposure east of Billefjorden, a distinctive, dark-grey micritic bed over 50 m thick occurs at the base (the 'Black Crag'; see below). Division: The Cadellfjellet Member is subdivided regionally into three as described above, with the type section in the Billefjorden area in the east, becoming the Kapitol Member in the central region and the Morebreen Member in the west. However, the main lithological subdivisions are the 'Beds' originally defined by Cutbill & Challinor (1965) - the Mathewbreen, Gerritbreen and Jotunfonna beds. The Mathewbreen Beds comprise the dolomitic limestones and dolomites of the formation. They are 34 m thick on Cadellfjeltet, but pass eastwards into arenites. In eastern Dickson Land they are up to 39 m thick, and occur as a thin outlier further west. They contain the Rugofusulina arctica zone fusulinid assemblage. They are not known west of Dickson Land. The distribution of these beds indicates some slight erosion at their top (prior to the Permian transgression) and in the west, the base is slightly unconformable on the underlying Gerritbreen Beds which have undergone some erosion (see below). The Gerritbreen Beds are limestones, mainly massive micrites and sparites, with a Waeringella usvae zone fusulinid assemblage. The beds occur right across the Nordfjorden Block where they are 30-50 m thick, with a marked thinning over the East Dickson Land Axis. A slight unconformity occurs at the top where the upper part of the W. usvae zone is locally absent and at the base where the underlying Jotunfonna Beds are also locally missing. In the east at Cadellfjellet they are 67 m thick. The Jotnnfonna Beds are grey bedded limestones and interbedded buff dolomites, with a Wedekindellina zone fusulinid fauna. A thin basal conglomerate occurs locally. On Kolosseum, the bottom 5-10m contain a Profusulinella zone fauna and are the oldest Middle Carboniferous beds so far found on the Nordfjorden Block. The beds are 50 m thick on the west side of Billefjorden, 30-50 m thick across the Nordfjorden Block, but are locally absent along the East Dickson Land Axis. They are not recognised on the east side of Billefjorden. The 'Black Crag' is a distinctive bed of massive dark grey micrite, over 50 m thick, found in the Adolfbukta region of Billefjorden. The lower 10-20m are commonly brecciated and it forms an excellent marker horizon in that area (Gee et al. 1953), but elsewhere it is much coarser-grained and cannot be distinguished from the rest of the formation. The Pyefjellet Beds occur to the east and in part replace the Black Crag (Pickard et al. 1996). Palaeontology and age: The formation contains a rather sparse fauna, of which brachiopods, molluscs, corals, trilobites, bryozoans and fusulines have

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been described (Gobbett 1964; Forbes et al. 1958; Cutbill 1968). No macrofauna was recorded across the Nordfjorden Block except for a few brachiopods reported by Gobbett (1964): Krotovia? sp.; ?Chaoiella cf. taiyuanfuensis (Chao); Choristites sp.; and Spiriferina sp. These may, however, come from the overlying formation, although fossils do undoubtedly occur in the Cadellfjellet Formation there. The coral, bryozoan and brachiopod faunas in eastern areas imply a Late Carboniferous age, and the strata were first assigned to the Triticites zone (Forbes et al. 1958). The fusulinids are abundant, Cutbill's work on them defined two zones. The upper Rugofusulina arctica zone correlates with the latest Carboniferous (Gzelian) of the Russian Platform, and is found in the Mathewbreen Beds. The lower Waeringella usvae zone correlates with the Gzelian and Kasimovian stages and occurs in the Gerritbreen Beds. At Kolosseum, the basal 5-10 m contain a Profusulinella zone (Early Moscovian) fauna, and the 'Black Crag' contains Wedekindellina sp. and the coral Bothrophyllum conicum, both of which indicate a latest Moscovian age (Wedekindellina zone). Thus the formation has a Kasimovian-Gzelian age, except for these local Moscovian units.

4.7.3

Minkinfjellet Formation (Campbellryggen Subgroup)

T h e Minkinfjellet Formation is p r e s e n t in the Billefjorden area only. It is a u n i t with steep lateral a n d vertical facies variations. It has a thickness o f 3 0 0 - 4 0 0 m with its m a x i m u m a d j a c e n t to the Billef j o r d e n F a u l t zone (Fig. 4.12) w h i c h c o n t r o l l e d d e p o s i t i o n . It consists m a i n l y o f c a r b o n a t e s , s a n d s t o n e s a n d evaporites, with red c o n g l o m e r a t e s in places. D e p o s i t i o n o c c u r r e d d u r i n g M o s c o v i a n time, p r o b a b l y in fluvial fans b u i l d i n g o u t into a m a r i n e basin. S a b k h a s a n d l a g o o n s d e v e l o p e d o n the fan b u t were subject to r a p i d base-level changes.

Definition: The Minkinfjellet Fm consists of a variable sequence of carbonates, sandstones and evaporites which occur mainly within the Billefjorden Trough, below the massive limestones of the Cadellfjellet Member. The sequence was first described by Scottish Spitsbergen Syndicate geologists, who introduced the term 'Passage Beds' in unpublished reports (Tyrrell 1919; Wordie 1919). Gee, Harland & McWhae (1953) gave further stratigraphic details, including the strata in the Campbellryggen Group. The unit was defined as a member within the Nordenski61dbreen Fm by Cutbill & Challinor (1965) and raised in rank by Dallmann (1993). It is thickest (300-400m) within the Billefjorden Trough adjacent to the Billefjorden Fault Zone, becoming thinner to the southeast. The Jotunfonna Beds at the base of the Cadellfjellet Formation (see above) occur on the west side of Billefjorden interleaved with the formation, but have not been identified to the east. The upper boundary is conformable and is marked in the Adolfbukta area by the overlying 'Black Crag' of the Cadellfjellet Mbr (see above). Elsewhere the top is marked only by the appearance of W. usvae zone fusulinids in the overlying strata. The base is apparently conformable within the trough, at the base of the Carronelva Beds, although this contact is probably disconformable (Dallmann 1993), as in the eastern area those beds overlap the Ebbadalen Formation and rest unconformably on pre-Devonian basement. On the western edge of the Billefjorden Trough, the formation overlaps the Billefjorden Fault zone and lies with distinct unconformity on various horizons of the Billefjorden Group. The formation is variable in thickness from 50m to 350m (Dallmann 1993). Lithologies: The type section is at Minkinfjellet. The formation is characterized by facies variation. It is dominated by carbonates, with dolostone, limestone, sandy limestone, marly limestone, limestone conglomerate and limestone breccias present. Coarse clastic rocks, generally yellowish or greenish in colour, are interbedded with the carbonates in places, as are thin beds of gypsum which also lines vugs in limestones. Limestone/dolostone breccias occur in the middle of the formation. Lateral variability is common within the formation. In places, grey, fossiliferous limestones (biomicrites and biosparites) are commonly interbedded with dolostones. In eastern Ny Friesland, the limestones become arenaceous and pass laterally into calcareous sandstones. Buff-coloured, micritic dolostones occur associated with evaporites and pass eastwards into limestones. A laterally restricted gypsum-anhydrite facies occurs in the central part of the trough. The evaporites are interbedded with dolostones which they pass into eastwards. To the west, towards the Billefjorden Fault Zone, they pass into clastic rocks.

Immediately adjacent to the fault zone, thick red and variegated conglomerates and sandstones occur in considerable thicknesses, comprising the whole formation. The red colouration may in part be secondary as the conglomerates are commonly derived from Devonian red-beds to the west. Division: In view of the lateral facies variation, widespread lithostratigraphic subdivision and correlation of the formation is difficult. Cutbill & Challinor (1965) originally recognized four u n i t s - the Carronelva, Elsabreen, Pyramiden and Anservika beds. However, Dallmann (1993), after Norsk Polarinstitutt remapping of the area, thought that the Pyramiden Beds and Elsabreen Beds were in fact the same unit. Furthermore, he thought that they are the lateral continuation of the Ebbadalen Formation to the south. He retained the Carronelva and Anservika beds but upgraded them to member status, and introduced a new unit, the Fortet Mbr, to the formation. The Anservika beds were indeed the equivalent of the Terrierfjellet beds (SKS). The Carronelva Mbr forms the lower part of the formation in central and northern areas. It is 41 m thick at its type locality, increasing to over 100 m in Ebbadalen and Ragnardalen. The base of the member is normally coarsegrained, either in the form of red conglomerates and other clastic lithologies or yellowish polymict conglomerates and sandstones. Yellowish sandstones continue through the middle of the member and are sulphurous in places. The upper strata consist of shales, marls, limestones and sandy limestones with some gypsum vugs. The member interfingers with the Anservika Mbr in its upper levels, and is overlain by either carbonates of that member or by breccias of the Fortet Member. The Terrierfjellet Mbr: The member is mainly exposed in eastern and southern parts of the Billefjorden Trough, but it is also present in the upper levels of the formation in central and northern areas. It consists of limestones and dolostones, interbedded with minor marls and marly limestones. Flint concretions and layers occur in the west of the outcrop, as also do rare gypsum layers. The thickness of the member varies from 33 m thick at the type section to 250-300 m in the central part of the outcrop. The Fortet Mbr: This member was defned by Dallmann (1993) for the intraformational carbonate breccias and conglomerates that are abundant in the upper part of the formation around the head of Billefjorden. The rocks overlie or replace (in the north) the carbonates of the Anservika Member. The breccias are probably of both in-situ brecciation and transported origin; grain- and matrix-supported varieties occur, with unsorted angular clasts up to 10cm in diameter. Dallmann estimated the member to be thickest at its type locality (approx. 240m).

Palaeontology and age: Limestones from the formation contain a marine fauna of which brachiopods, bivalves, corals and foraminifera have been described. The brachiopod assemblage compares with that of the Middle Carboniferous of the Moscow Basin (Gobbett 1964) and Cutbill's (CSE) Wedekindellina and Profusulinella zones are represented which correlate with the Moscovian stage. Crinoids were reported by Dallmann (1993).

4.7.4

Ebbadalen Formation (Campbellryggen Subgroup)

T h e E b b a d a l e n F o r m a t i o n is o n e o f the best k n o w n lithostratig r a p h i c units o f Svalbard. Like overlying units its d e p o s i t i o n was c o n t r o l l e d by its p r o x i m i t y to the Billefjorden F a u l t zone; it is t h e r e f o r e also laterally variable with wedges t h i n n i n g a w a y f r o m the fault in a h a l f graben. It is c h a r a c t e r i s e d by alluvial fan red-beds at the base a n d a d j a c e n t to the fault, which die o u t a w a y f r o m it a n d pass into two m e m b e r s . In the u p p e r p a r t o f the m a i n basin sequence are c a r b o n a t e s a n d evaporites; in the lower p a r t fluvial s a n d s t o n e s a n d shales. T h e total t h i c k n e s s o f the f o r m a t i o n is in the o r d e r o f 750 m b u t this decreases to the east a w a y f r o m the fault to zero. T h e f o r m a t i o n c o n t a i n s a variety o f f a u n a that indicate a B a s h k i r i a n age.

Definition: The Ebbadalen Formation is equivalent to the Lower Gypsiferous Series of Gee, Harland & McWhae (1953) but excludes the lateral equivalents of the Minkinfjellet Formation. The formation occurs only in the BiUefjorden Trough, and like the overlying Minkinfjellet and Cadellfjellet units is thickest adjacent to the fault zone on the western margin of the trough, where up to 750m are preserved. It thins rapidly to the east and pinches out about 25kin east of Billefjorden. The type section is at Ebbadalen with reference sections at Cadellfjellet, Odellfjellet and elsewhere. The formation was defined by Cutbill & Challinor (1965) and has been described by Holliday & Cutbill (1972) and Johannessen & Steel (1992).

THE CENTRAL BASIN The upper boundary of the formation is marked by the appearance of the sandstones of the overlying Carronelva Beds, above which cherty carbonates occur and evaporites are rare. The lower boundary is above the red beds of the Hultberget Formation which overlies the coal-bearing sequences of the Billefjorden Group. Lithologies: Facies are extremely variable as Gypsum-anhydrite rocks are an important constituent of the upper part of the formation especially, and are widely developed in the central part of the Billefjorden Trough. They are of the nodular type and formed during early diagenesis in soft sediments (Holliday 1967, 1968). Gypsum was the primary sulphate mineral deposit, while anhydrite formed by solution and reprecipitation. Sandstones form a major constituent of the lower part of the formation. They are light coloured, white, red and green, generally fine-medium grained with horizontal and both large and small-scale cross-stratification. In the central part of the basin they are commonly interbedded with carbonates and shales. Black shales occur with the sandstones in the lower part of the formation; in Ebbadalen, the shales form a thick, clearly defined horizon (the Ebbadalen Shale Beds). Red sandstones, conglomerates and shales occur interbedded in the upper part of the formation adjacent to the fault belt. Conglomerates and sandstones also occur in the east of the basin, e.g. at Cadellfjellet, where they form the Margaretbreen Conglomerate facies. Red beds also occur across the area at the base of the formation. Skeletal calcarenites, commonly oolitic, with sparry calcite cement and little or no lime mud, occur in the east and as thin horizons elsewhere. Locally, a limestone breccia (the Ragnarbreen Breccia of McWhae 1953) is developed at the top of the Ebbadalen Formation. As there is no evidence of tectonism and it occurs in abnormally thin sections lacking sulphates, it is thought to be a solution breccia, resulting from the removal of sulphates. Division: Holliday & Cutbill (1972) examined the complex lateral facies variations within the formation and defined a number of local members, beds and 'facies'. Detailed mapping of key limestone horizons allowed correlation of the different facies. Johannessen & Steel (1992) defined a further member within the formation, and redefined the base to include the red beds of the Hultberget Member, which had previously been assigned to the underlying Svenbreen Formation. The Odellfjellet Mbr: Johannessen & Steel (1992) introduced the member for alluvial fan and related deposits that occur adjacent to the Billefjorden Fault zone. These deposits were originally referred to as the Lower and Upper Red Bed Facies of the Trikolorfjellet Member by Holliday & Cutbill (1972). They consist of red, grey and yellow conglomerates and sandstones, red shales (with gypsum nodules in places) and yellow dolostones. In the lower red beds, conglomerate clasts are mainly quartzose, sorting is poor, stratification irregular and there is rapid lateral variation. The member is up to 400 m thick adjacent to the fault, but to the east it thins considerably and interdigitates with the Trikolorfjellet Member. On the west side of Billefjorden, the 'Pyramiden Conglomerate' (= Pyramiden Beds and equivalent to Elsabreen Beds of Cutbill & Challinor 1965; Dallmann 1993) consists of a group of rudites adjacent to the Billefjorden Fault zone, where they comprise the entire formation and are 300-400m thick. Originally placed in the Minkinfjellet Fm they are now considered to be equivalent to the Odellfjellet Mbr and are placed within it (Dallmann 1993). The Trikolorfjellet Mbr: The type section of the member is in Ebbadalen where it is 186 m thick, although it is thickest (326 m) at Trikolorfjellet from where it is named (Holliday & Cutbill 1972). The member is laterally variable in facies and lithologies; it mainly contains gypsum-anhydrite rocks with interbedded carbonates, but the evaporites are replaced to the west by red shales and then by sandstones and conglomerates of the Odellfjellet Mbr, with which it is equivalent. Thin black limestones and dolostone interbeds are common throughout. A basal sandy fossiliferous limestone is incised as much as 40 m into the underlying strata. Elsewhere, the base is conformable and defined at the bottom of the red beds. In some areas (e.g. at Trikolorfjellet), the Odellfjellet and Trikolorfjellet members interdigitate to the extent that red and white coloured lithologies appear to be cyclic (each cycle typically 15-30m thick), consisting of upward-coarsening red sandstones and conglomerates capped by a white quartzitic sandstone, which is in turn overlain by dolostone (fossiliferous at some levels). Holliday & Cutbill (1972) introduced the term Teltfjellet Mbr for the eastern lateral equivalent of the Trikolorfjellet Mbr. However, this term has fallen into disuse, as the two members may be difficult to distinguish, and therefore the strata are included within the Trikolorfjellet Mbr. The type section of the Teltfjellet Mbr was on Cadellfjellet, where evaporites occur with the same widespread limestone beds as to the west. The carbonates thicken to the east in the upper part of the member in north Biinsow Land and finally form the continuous Urmstonfjellet Limestone Bed. The base of the

71

member is unconformable in the east, where it oversteps onto the Ebbaelva Mbr (Gerritelva Sandstone Mbr of Holliday & Cutbill; see below), the Llulberget and Mumlen fms and the Hecla Hoek basement. The Ebbaelva Mbr: This member comprises grey and yellow sandstones interbedded with grey-green shales. They occur in discontinuous upwardfining cycles in the central and northern parts of the area. Thin black dolomites and white nodular gypsum and anhydrite are interbedded towards the top of the member. In the Ebbadalen area, Holliday & Cutbill identified two sub-units- the upper Ebbabreen Shale Beds and lower Ebbabreen Sandstone Beds, although it is unclear whether they can be traced further than the local area and the names have not been used in later literature. Holliday & Cutbill also introduced the Gerritelva Member. As with the Teltfjellet Member, the name has fallen into disuse, with the strata included in the Ebbaelva Mbr (e.g. Johannessen & Steel 1992) as they are probably the lateral equivalent of the Ebbabreen Sandstone Beds. The Gerritelva Mbr was defined to include 0-70 m of sandstones occurring east of Adolfbukta, containing both horizontal and large-scale cross-bedding and some pebble horizons. The beds are flaggy to massive and commonly gypsum-cemented. Palaeontology and age: Once thought to be unfossiliferous, the Ebbadalen Formation is now known to contain a wide variety of fossils including crinoids, corals, brachiopods and fusulinids. Only the latter two groups have been described to date. These occur mainly in dolostones and shales of the Ebbaelva Member. The brachiopods described by Gobbett (1964) and Holliday (pers. comm.) are on the whole too wide-ranging for an accurate age correlation. However, the occurrence of Striatifera sp. in dolostones high in the Ebbaelva Member and in the basal limestones of the Trikolorfjellet Member may be significant as this genus has previously been regarded as restricted to the Early Carboniferous epoch (Muir-Wood & Cooper, 1960). Fusulinids from the upper part of the formation belong to the P. antiqua zone of Cutbill and correlate with the Bashkirian stage of Russia. No Moscovian species occur below the Minkinfjellet Member, and the top of the Ebbadalen Formation probably corresponds to the Bashkirian/Moscovian boundary. The formation is therefore of Bashkirian age.

4.7.5

Hultberget Formation (CampbeHryggen Subgroup)

This u n i t was originally the (upper) H u l t b e r g e t M e m b e r o f the S v e n b r e e n F o r m a t i o n o f the Billefjorden G r o u p (Cutbill & C h a l l i n o r 1965), the lower S v e n b r e e n U n i t being the S p o r e h o g d a M e m b e r . H o w e v e r the N o r s k P o l a r i n s t i t u t t m a p p e d a b r e a k b e t w e e n the t w o m e m b e r s a n d t h e H u l t b e r g e t u n i t h a d m o r e affinity with the overlying strata because o f its red beds. T h e S v e n b r e e n F o r m a t i o n was t h u s d i s c o n t i n u e d as a useful m a p p i n g u n i t a n d divided b e t w e e n C a m p b e l l r y g g e n S u b g r o u p a n d the Billefjorden G r o u p . T h e H u l t b e r g e t M e m b e r o f Cutbill & C h a l l i n o r was described as 7 9 m thick w i t h a coal s e a m at the base a n d overlain by grey to red shales a n d s a n d s t o n e s . T h e coal s e a m has m o r e affinity w i t h the newly defined M u m i e n F o r m a t i o n below. T h e f o r m a t i o n consists o f red a n d p u r p l e shales, m u d s t o n e s , siltstones, s a n d s t o n e s a n d thin i r o n s t o n e b a n d s w h i c h m a y be recystallized l i m o n i t i c m u d s . L i m e s t o n e n o d u l e s m a y also o c c u r in s o m e o f the shale beds. M o s t beds are parallel l a m i n a t e d or crossb e d d e d ; s a n d s t o n e s are fine to m e d i u m grained. N o r t h w e s t o f Elsabreen, c o n g l o m e r a t e layers are present. T h e strata p r o b a b l y r e p r e s e n t s t r e a m a n d o v e r b a n k d e p o s i t s w i t h i n a n d a d j a c e n t to alluvial fans at the base o f the fault.

4.8

BiHefjorden Group (Early Carboniferous)

I n the c u r r e n t s c h e m e the Billefjorden G r o u p in the type area is n o w defined by the t w o c o n s t i t u e n t f o r m a t i o n s : M u m i e n a n d H o r b y e b r e e n (SKS, D a l l m a n n et al. 1996). This r e a r r a n g e m e n t resulted f r o m the division o f the S v e n b r e e n F o r m a t i o n o f Cutbill & C h a l l i n o r (1965) into its u p p e r H u l t b e r g e t M e m b e r , d i s t i n g u i s h e d by red beds, to b e c o m e the lowest f o r m a t i o n o f the G i p s d a l e n G r o u p a n d the lower S p o r e h o g d a M e m b e r to be redefined as the newly n a m e d M u m i e n F o r m a t i o n .

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CHAPTER 4 unconformably on the Hecla Hoek metamorphic basement with a thin basal conglomerate of locally-derived pebbles. Lithologies: Two lithofacies can be distinguished in the formation constituting the two members. The upper member consists of dark grey or black carbonaceous shales, associated with thin coals and some sandstones. The lower member in Dickson Land is characterized by massive, lightcoloured, thick-bedded, coarse sandstones (Johannessen & Steel 1992).

Since the C a m b r i d g e w o r k , m o s t s e d i m e n t o l o g y a n d stratigrap h y has been carried o u t either by g r o u p s f r o m the University o f Bergen (Gjelberg & Steel 1981; Gjelberg 1987; J o h a n n e s s e n & Steel 1992) or the N o r s k P o l a r i n s t i t u t t , w h o have recently r e - m a p p e d the area ( L a u r i t z e n et al. 1989, C 8 G ; D a l l m a n n 1993; D a l l m a n n et al. 1994, C7G). B o r e h o l e a n d seismic d a t a have also been collected by oil c o m p a n i e s interested in the area, s o m e o f w h i c h have been p u b l i s h e d ( Y e v d o k i m o v a , V o r o k h o v s k a y a & B i r y u k o v 1986).

4.8.1

The Birger JohnsonqeUet Mbr: This is the coal-bearing part of the formation, made up of small cycles of shale and siltstone which are locally carbonaceous and pass into coaly shale and coal. Plant remains are common. Up to 18 coal seams are present, from 0.1-1.45 m in thickness. Underlying root horizons or soil profiles are absent, although root horizons do occur elsewhere in the member (Abdullah et al. 1988). There is considerable lateral facies variation and also thickness variation (7-57 m) within the member. The base is defined as the first thick sequence of coal seams. The Sporeh~gda Mbr: This member consists mainly of massive white, thickbedded, coarse sandstones 20-76m thick. The whole unit shows crossbedding, wash-outs and rapid lateral changes in thickness of individual beds. Allochthonous plant debris and coaly clasts are common. Sandstones in the lower part contain large carbonaceous fragments and moulds of Lepidodendron stems. Towards the east, shales occur between the sandstone units. In the Ebbadalen area, the facies is fine-grained and contains several thin coals, which are usually associated with carbonaceous black shales containing plant remains, into which they pass laterally and vertically. Only rarely, e.g. at Hultberget, north of Ebbadalen, do the coals lie on a rootlet horizon. Although the individual seams have little lateral continuity, the coals fall into three recognisable horizons, two of which can be traced over quite a wide area. In places the shales contain ironstone concretions, but they are not as abundant as in the overlying Birger Johnsonfjellet Mbr. There is a thin basal conglomerate of locally-derived pebbles where the sandstones rest directly on basement rocks, which is absent elsewhere. Otherwise, medium and coarse conglomerates are rare. Yevdokimova et al. (1986) correlated the upper part of this coal-bearing facies in their section, only a small distance to the south, with that of the Birger Johnsonfjellet Mbr west of Billefjorden.

Mumien Formation

This f o r m a t i o n is the lower p a r t o f the original S v e n b r e e n F o r m a t i o n , its u p p e r b o u n d a r y being below the lowest red beds o f the H u l t b e r g e t F o r m a t i o n . It is a t e r r i g e n o u s u n i t p r e s e n t in the Billefjorden area, with a thickness o f u p to 230 m. It c o n t a i n s two m e m b e r s - Birger J o h n s o n f j e l l e t a n d S p o r e h o g d a . T h e S p o r e h o g d a M e m b e r c o n t a i n s massive coarse s a n d s t o n e s w i t h m i n o r shales a n d a l l o c h t h o n o u s coal, w h e r e a s the Birger J o h n s o n f j e l l e t M e m b e r c o n t a i n s n u m e r o u s coal seams w i t h i n a p r e d o m i n a n t l y shale a n d siltstone sequence (Fig. 4.13). T h e f o r m a t i o n is i n t e r p r e t a t e d as a terrestrial unit, with dep o s i t i o n w i t h i n a large fluvial system for the S p o r e h o g d a M e m b e r b u t c h a n g i n g to lacustrine a n d v e g e t a t e d f l o o d p l a i n e n v i r o n m e n t s for the Birger J o h n s o n f j e l l e t M e m b e r . D e p o s i t i o n o c c u r r e d d u r i n g Visean a n d possibly into S e r p u k h o v i a n time.

Definition: The Svenbreen Fm was defined by Cutbill & Challinor (1965) as 'the upper coarse sandstone series' of the Billefjorden Gp which crops out only in the East Spitsbergen Basin. The Mumien Fm was introduced (SKS, Dallmann et al. 1996) for the lower member of the Svenbreen Fm. The type section is on Birger Johnsonfjellet. Thicknesses are greatest to the east of the Billefjorden Fault Zone, with a maximum of 230m at the northern end of Billefjorden. The formation thins rapidly to the west and east and is absent west of the East Dickson Land Axis and in central and eastern Olav V Land. The upper boundary is here redefined as the base of the alluvial red bed sequence of the Hultberget Fm (Campbellryggen Subgroup), which locally rests on the coal-bearing strata below (Cutbill & Challinor 1965). In most of Dickson Land the Cambpellryggen Subgp is absent and the Mumien clastic rocks are overlain by limestones of the Dickson Land Subgp. The basal sandstones of the Mumien Fm in the west are concordant on the upper shales of the Horbyebreen Fm below, though there may be a disconformity, as in the east the lower formation is absent and the Mumien Formation rests

Rock units 13_

Thin-bedded sandstones and shales, commonly red

Red-beds, sandstones and conglomerates

Gjelberg & S t e e l (1981)

O n(3 Z I.U -J < a (f) 13_

Gjelberg (1987)

Abdullah et al. (1988); Michelsen & Khorasani (1991)

Johannessen & Steel (1992)

Dallmann (1993); McCann & Dallmann SKS and this work (1995)

EBBADALEN FORMATION

Hultberget Mbr

Hultberget Mbr

SVENBREEN FM

HULTBERGET FM

13_ O n~ (_9 Z LU J < a co

13. m (~

Hultberget Mbr

Coal-bearing siltstone / shale sequence

s :~ O r~ (.9

Massive thick-bedded sandstones

Z Ill r'~ I:::E O ii UJ "J ._]

Siltstones, shales and coal

Cutbill & Challinor (1965)

Palaeontology and age The formation contains a plentiful Early Carboniferous macro-flora (Forbes et al. 1958) and micro-flora (Playford 1962/1963), described in Chapter 17. In general it is difficult to separate the Mumien and Horbyebreen formations on palaeontological grounds, as no stratigraphically separate assemblages are apparent in the macro-flora. However, Playford (1962/1963) recognized his Aurita microspore assemblage in the Mumien Formation and upper Horbyebreen Fm, concluding that these strata have a Visean age, possibly extending to earliest Serpukhovian. There is some statistical evidence that this assemblage can

SVENBREEN FORMATION

Birger Johnsonfjellet Mbr

Birger Johnsonfjellet Mbr Sporehegda Mbr (Herbyebreen Fm)

Sporeh~gda Mbr

Fig. 4.13. Stratigraphic schemes for the Billefjorden Group.

MUMIEN FM

Z

Sporehegda Mbr

HORBYEBREEN FORMATION Hoelbreen Mbr Triungen Mbr

13_ O r~ (3 UJ a n," O ii Ill ._A .,,A m

THE CENTRAL BASIN be subdivided at the junction betweenthe Mumien and Herbyebreen fms (Cutbill & Challinor, 1965) and that this may approximate the ViseanSerpukhovian boundary. Retiolites radforthii Staplin, is found only in the Mumien Fm. In this case, the Mumien Fm would be entirely Serpukhovian.

4.8.2

Harbyebreen Formation

The H e r b y e b r e e n F o r m a t i o n lies u n c o n f o r m a b l y on Proterozoic basement rocks in D i c k s o n L a n d and s o u t h e r n N y Friesland. It is variable in thickness f r o m 57 to 2 0 0 m thinning to the west. It contains sandstone, conglomerate, shale a n d coal, c o m m o n l y occurring in cyclic sequences. The lower part of the f o r m a t i o n is d o m i n a t e d by the coarser-grained lithologies a n d assigned m e m b e r status (Triungen Member); the u p p e r part contains most o f the shales and coals and forms the H o e l b r e e n M e m b e r . Deposition is t h o u g h t to have been in a continental setting within a small and restricted basin. It was p r o b a b l y f a u l t - b o u n d e d to the east, a n d the sediment source was also probably in that direction. Facies show large lateral variations. The T r i u n g e n M e m b e r was mainly deposited by westward-flowing braided streams with o v e r b a n k deposits; the H o e l b r e e n M e m b e r by n o r t h w a r d - f l o w i n g m e a n d e r i n g streams in a s w a m p y floodplain environment. The f o r m a t i o n is o f T o u r n a i s i a n and possibly of Late F a m e n n i a n a n d / o r Visean ages on the basis o f microflora.

Definition: The unit was defined by Cutbill & Challinor (1965) as the lower formation of the Billefjorden Gp. It is restricted in outcrop to central Dickson Land and southern Ny Friesland. The upper boundary may be a disconformity in view of the basal Mumien Fm overstep to the east, but sandstones of the Mumien Fm concordantly overlie the shales at the top of the Herbyebreen Fm. The base is unconformable on preCarboniferous rocks. Lithologies and division: The formation consists of a cyclic sequence of shales, coals, sandstones and conglomerates from 57-200m thick. Fine sediments and coals predominate in the upper part, while the lower part consists entirely of sandstones and conglomerates. This has led to a division into two members: the Hoelbreen and Triungen Mbrs. Hoelbreen Mbr: The type section for the Hoelbreen Member is on Birger Johnsonfjellet where it is 146m thick. The member thins markedly to the west, e.g. at Gonvillebreen it is only 54 m thick. Within this upper member, thinly bedded, cyclic and laterally persistent coal-bearing carbonaceous shales and siltstones predominate. The siltstones show occasional low-angle cross-bedding, though it is usually flat or wavy. Dark grey, shaly, micaceous argillites, 0.5m thick usually occur above the coal seams. Fine-grained sandstone interbeds up to 2 m thick and showing some cross-bedding occur, especially in the east, in the lower part of the sequence, but they are locally developed and laterally impersistent. 10-15 cycles of sand-silt-clay-coal have been recognised. 10% of the member is sandstone; 50% is dark grey siltstone containing plant remains; 20% is made up of argillites and 20% of coal. The coals are generally quite thin and die out laterally, but they are more extensively developed in two well-defined horizons in the south-east of the outcrop, seams varying in thickness from 0.66-7.4 m. In the region of Pyramiden, the coals are sufficiently thick (up to 9m) to be mined. Transported plant remains are common in all lithologies, but are generally poorly preserved. In-situ plant fossils are rare and there is generally a lack of seat-earths, indicating that the coals are mainly allochthonous. However, seat-earths and rootlet beds are present locally. Triungen Mbr: The type section of this lower member is beside Gonvillebreen where it is 99 m on Odellfjellet. There is a general reduction in coal and carbonaceous material towards the west. Thicknesses are irregular, from 5-100m due to lateral facies variations. The dominant lithologies are thick-bedded sandstones and almost uncemented heterogeneous conglomerates. The latter show coarse cross-bedding and contain a variety of pebbles, including white, pink and purple quartzites, black and grey chert and rare mica-schist. The upper 20m are less conglomeratic, and there is a transition into the carbonaceous sandstones and shales of the Hoelbreen Mbr. The upper boundary is at the top of the highest thickbedded sandstone. The conglomerates around the Billefjorden Fault Zone, e.g. at Birger Johnsonfjellet, are noticeably coarser than further west, e.g. at Gonvillebreen.

73

Palaeontology and age: There is an abundant macroflora in the Mumien and Horbyebreen Formations, though no stratigraphically separate assemblages have been recognized. However, the microflora has proved more useful. Playford (1962/63) recognized his two distinct assemblages in these strata, defining the Aurita and Rarituberculatus zones, which indicate a Visean and Tournaisian age. The lower Rarituberculatus (Tournaisian) assemblage is restricted to the Horbyebreen Fm. However, the lower member does not yield a microflora, except in its uppermost part. The upper Hoelbreen Mbr contains the Rarituberculatus assemblage for more than half its thickness. There is then a break, and the overlying strata contain the Aurita assemblage. This break is not marked by any lithological change. The Aurita assemblage is also present in the overlying Mumien Formation but there is some evidence that the Aurita assemblage can be subdivided at the disconformity between the Mumien and Horbyebreen fms which may mark the Visean/Serpukhovian boundary (Cutbill & Challinor 1965).The assemblage, according to Playford, could possibly extend to Early Serpukhovian time. The Horbyebreen Fm is thus of Tournaisian and Visean age. However, given the rarity of preserved palynomorphs from most of the Triungen Member, it is possible that the lowest part may have a Famennian age, and this appears to have been confirmed (van Veen, pers. comm.).

4.9

The structure and development of the Central Basin

The Basin is d o m i n a t e d by three kinds of Paleogene structure. (i) The eastern front o f the thrust a n d fold belt of the West Spitsbergen O r o g e n m a r k s a distinct b o u n d a r y w h e t h e r a steep m o n o c l i n e or an eastward verging thrust front. (ii) In line of the fault, the Billefjorden a n d L o m f j o r d e n fault zones, thrust structures have c o n c e n t r a t e d also with easterly vergence resulting in some thickening. These structures a p p e a r to have been generated t h r o u g h the Paleogene strata or to the n o r t h t h r o u g h decollement zones in Mesozoic and Paleozoic strata. The G i p s h u k e n F o r m a t i o n contains examples o f such bedding-shear as m o n i t o r e d in the ellipsoidal a n h y d r i t e - g y p s u m concretions. Similar facies in the lower gypsiferous strata in the Billefjorden t r o u g h were protected by the N o r d f j o r d e n H i g h ( H a r l a n d , M a n n & T o w n s e n d 1988). The result was d e f o r m a t i o n c o n c e n t r a t e d in the older fault zones (Fig. 4.14; Andresen, H a r e m o & Bergh 1988). (iii) T h e m o s t obvious feature of the Central Basin is the oval shaped o u t c r o p o f the Paleogene strata in which the d e p o c e n t r e shifted s o u t h w e s t w a r d s so that at places, w h e r e the strata are

WEST

EAST

I Tp --'~ f-I (a)FLOWERDALEN-MARMIERFJELLET

Sea level 1000 metres

i

5OO

1'.0

2.0

kilometres of Festningen sandstone

__f••.base ~

f- I

~

-

-

-

-

~

T#r_- - _ ..-,,/.,-I KT ....

~

~

~_._..---..~ KT

s

~'Sea level

(b) A D V E N T D A L E N - ESKERDALEN (north side)

base of C r e t a c e o u s shale

~ f-I (c) REINDALEN (south side)

~ ~t'"-base of Festningen sandstone

Abbreviations: T - Tertiary Ju - Upper part of the Janusfjellet Subgroup JI - Lower part of the Janusfjellet Subgroup

Sea level

KT - Kapp Toscana Formation S - Sassendalen group TP - Tempelfjorden group f-I - fault line

Fig. 4.14. Simplified structural cross-sections of the Central Basin (from Parker, 1966) to show deformation and tectonic thickening above the southern extension of the Billefjorden Fault Zone, f-1 in sections (a), (b) and (e), and the anticline thrust structure diverging to the east, south of the fault in Nordenski61d Land.

74

CHAPTER 4

thickest, they are truncated by faulting (probably transpressive) along the west Spitsbergen orogenic front (e.g. Steel et al. 1981). The structure has been further delineated by seismic studies of the Polish group (Guterch et al. 1978; Guterch, Pajchal & Perchuc 1982; Guterch & Perchuc 1990). It is not so obvious to what extent a Mesozoic basin structure coincided with the Central Basin. Because the basal Paleogene Firkanten Formation unconformably oversteps northwards successive members of Early Cretaceous Carolinefjellet Formation in a seemingly plane erosion surface which itself was followed by southward tilting of Spitsbergen. Late Triassic strata thicken eastwards and Early Triassic strata possibly westwards away from a delta source, so that there is an incipient differential Sassendalen Group subsidence in the west along the orogen. Late Paleozoic structures are best seen emerging northwards, and Early Carboniferous strata reflect the Devonian fault pattern. West of the Billefjorden Fault Zone (BFZ) was the Nordfjorden High bounded on the West by the West Spitsbergen Fault Zone beyond which the St Jonsfjorden Trough is considered in Chapter 9. The Billefjorden Trough east of the BFZ and a similar less pronounced trough further east related to the Lomfjorden Fault Zone accumulated sediments in isolated basins before Wordiekammen Limestone times. It is suggested here that three successive groups of factors operated.

(1) During Carboniferous time especially, but right through Jurassic time at least, the three mentioned fault zones were intermittently reactivated but not in a strike-slip sense. (Chapters 17 and 18). (2) Upward tilting to the north was demonstrably active in late Cretaceous time with the elimination of Mesozoic strata beneath the Paleogene strata at around the latitude of Kongsfjorden so giving the characteristic outcrop pattern with the older rocks in the north. Just prior to this differential uplift was a marked Albian differential subsidence to develop a rapidly increasing thickening of the Carolinefjellet Formation. These two evidences may point to a single tilting operation in which differential mantle heating in the north replaced the long period of slow cooling platform subsidence. (3) The marked localisation of the Central Basin into the Central Tertiary Basin could well have a Paleogene strike-slip component as a partial pull-apart (transtensile) basin in its initial stages. When, by Late Palaeocene and Eocene time transpression, dominated the West Spitsbergen Orogeny compressive stresses were effective throughout the basin area as seen in structures localised especially near the old fault zones. Such compression could have contributed to a final downward buckling to depress the basin further in which sedimentation from the uprising welt filled the space available (Chapter 20).

Chapter 5 Eastern Svalbard Platform W . B. H A R L A N D 5.1 5.2 5.3 5.4 5.4.1 5.4.2 5.4.3 5.4.4 5.4.5 5.5 5.5.1 5.5.2 5.6

with a contribution by SIMON

Platform strata, 75 Igneous rocks, 76 Submarine outcrops, 76 Northeastern Spitsbergen, Wilhelmuya and Hinlopenstretet, 77 Northeastern Spitsbergen: Permo-Carboniferous terrane, 77 Northeastern Spitsbergen: Triassic terrane, 77 Wilhelmoya and Hellwaldfjellet, 77 Islands of Hinlopenstretet, 79 The structure, 79 Southwestern Nordaustlandet, 80 Earlier work, 80 Stratal succession, 81 Kong Karls Land (W.B.H. & S.R.A.K.), 83

The Platform sequence (of younger rocks) i.e. latest Devonian, Carboniferous/Tournasian through Albian (and excluding Tertiary strata on land at least) appears once to have extended east of Spitsbergen in one sheet of which little now remains above sea level. It comprises two supergroups: Bfinsow Land and Nordenski61d Land. The map (Fig. 5.1) illustrates that each of the islands rests on a much larger shelf, no deeper than 100 m and that with the exception

o~

5.6.1 5.6.2 5.7 5.7.1 5.7.2 5.7.3 5.7.4 5.7.5 5.8 5.8.1 5.8.2 5.8.3 5.9

Fig. 5.1. Map of the eastern platform area of Svalbard showing the main place names and principal bathymetric features (adapted from 1:2 000 000 bathymetry chart of the Western Barents Sea, Norsk Polarinstitutt, Oslo 1989; compiled by Kristoffersen, Sand, Beskow & Ohta).

Earlier work, 83 Stratal succession, 83 Barentsoya, Edgeoya and Tusenoyane, 86 Earlier work, 86 Stratal succession, 87 Sub-surface stratigraphy, 89 Biostratigraphy/age estimates, 89 Structure and igneous bodies, 91 Hopeu, 91 Earlier work, 92 Succession from outcrop, 93 Subsurface succession, 93 Correlation of four exploratory wells: Edgeoya and Hopeu, 93

of the outlying islands of Kong Karls Land and Hopen the 100m isobath contains them within the Spitsbergen shallows. In these circumstances, it would appear to be somewhat fortuitous as to what strata are preserved above sea level and it is perhaps remarkable that, if relatively thin strata with a maximum combined and exposed thickness in the area from (Tournaisian) through ?Barremian of c. 2 km, some representatives occur on each island with neither younger nor older rocks. If we plot the TriassicJurassic boundary, say the Rhaetian stage, it occurs at the top of the east Spitsbergen, south Nordaustlandet and south Edgeoya outcrops at heights respectively of about 550, 350 and 500 m a.s.l., at about 0-100 m at Kong Karls Land and at 370-300 m in Hopen. Thus departures from sea level over distances of 350 km N to S and 200 km E to W hardly exceed 500m with average gradients of perhaps 300m in 300 k m - about half a degree. It is therefore reasonable on present evidence exposed above sea level to refer to this as a platform. On the other hand local dips may be very much steeper. One might speculate that the highly resistant Kapp Starostin Formation may be in part responsible for the wide extent of the shallow water around the islands. One striking feature which distinguishes eastern from western Svalbard is the greater degree of Late Jurassic Early Cretaceous basic igneous activity, mainly evident in sills. They are often thick enough to form major topographical features and with evidence of volcanism in the east. Indeed in Kong Karls Land not only do lavas occur but the stratigraphic successions there appear to show more Mesozoic disturbance than elsewhere in Svalbard for this interval.

5.1

H~ y

R. A. K E L L Y

P l a t f o r m strata

In each area discussed the rock units named and employed are explained. The sedimentary (and volcanic) successions as recorded in the separate areas considered here are described in this chapter as follows. Northeast Spitsbergen and Wilhelmoya (Section 5.4) is, for convenience, taken as the area east of the Lomfjorden Fault in which mainly Permian and Triassic strata crop out. Latest Triassic and Jurassic strata are recorded in the tops of the mountains of Hellwaldfjellet and Wilhelmoya. The islands in Hinlopenstretet are mainly basic igneous rocks, presumably late Mesozoic sills and dykes. Southwestern Nordaustlandet (Section 5.5) is in effect an extension of the above mainland area with Permian-Triassic successions but no record of latest Triassic or Jurassic strata. The Paleozoic strata are seen to rest unconformably on Precambrian (Caledonian) basement.

76

CHAPTER 5

Kong Karls Land (Section 5.6) is a small isolated archipelago ranging Late Triassic through Early Cretaceous strata (with lava flows). Jurassic faunas are especially rich. Barentsoya, Edgeoya and Tusenoyane (Section 5.7) is a large, almost exclusively Triassic terrane with three minor Permian inliers but no Rhaetian or younger strata recorded. The two islands are penetrated by late Mesozoic basic sills and such rocks form the thousand islands to the south (Tusenoyane). Two deep wells, Plurdalen-1 and Raddedalen-1 penetrate strata at least well into Early Carboniferous and possibly earlier units. Hopen (Section 5.8) is a singularly linear island again probably exclusively of Late Triassic strata. Two wells (Hopen-1 and Hopen-2) penetrate Early Triassic and Permian to Carboniferous strata. The four wells are compared in Section 5.9.

5.3

Data from the area roughly east of Nordaustlandet, Edgeoya and Hopen and west of longitude 35~ were recorded by Elverhoi & Lauritzen (1984) and yielded a map with predominant Quaternary rock fragments classified mainly as Hecla Hoek in the north around Kvitoya, as chert and silicified limestone (typical of the Tempelfjorden Group) south and east of southern Nordaustlandet and east of Edgeoya, with the remaining larger area yielding mostly sandstones probably Mesozoic. Elverhoi et al. (1989) divided the northwest Barents Sea into six structurally defined elements: 1. 2. 3.

5.2

Igneous rocks

The mainland of Spitsbergen, Nordaustlandet, Kong Karls Land, Barentsoya and Edgeoya are all characterized by basic intrusions. In addition Kong Karls Land exhibits volcanic lavas. The igneous activity spanned ?Kimmeridgian to Barremian time. Evidence also suggests that the rocks belong to one main igneous suite. Some of the characteristics will be mentioned here and not necessarily repeated under subsequent headings. One obvious feature is that the rocks are generally more resistant than their host strata which they protect. They thus crop out in a disproportionally large area for their bulk and often have a significant control of topography. Nearer to sea level the sedimentary rocks have often been removed and many small islands expose only basic rocks. This is typical of the islands in Hinlopenstretet, in Tusenoyane and around Kong Karls Land. It may well be that this is only part of a larger province well exemplified in the less accessible archipelago of Franz Josef Land. The petrology of these basalts, dolerites and occasional gabbros has been studied by relatively few workers because of their relative uniformity and the thorough nature of the early investigations. Historically the rocks were noticed by Nordenski61d with their peculiar 'hyperite' facies. This is softer rock and is not often encountered. Backlund was the first to make a systematic study of these rocks (1907a, b, 1908, 1911, 1920) from the Arc of Meridian Surveys of 1899-1901. The 1907 publication is a monograph on the 'diabases' of eastern Svalbard beginning with a thorough review of previous work, then outlining knowledge of the rocks in Spitsbergen. The principal work is on the Storfjorden rocks and especially those of Edgeoya and Barentsoya with a detailed description of their many occurrences. The main body of the work is petrographic with optical studies of the principal minerals, plagioclase, pyroxene, titano-magnetic, olivine and with notes on apatite and quartz and then with chemical analysis of the rocks including marginal facies. This laboratory work in St Petersburg can hardly be surpassed. The second fascicle (1908) described similar rocks observed in the course of a traverse from Johnstonbukta in Storfjorden to Billefjorden (via the high mountains including Backlundtoppen). Backlund (1907b) had already made a study of the Kong Karls Land and Franz Josef Land material collected on earlier expeditions. A more accessible and convenient study of the dolerite and basalts of Svalbard, and with further chemical analysis (Tyrrell & Sandford 1933) confirms the view of a variety of facies but still with a remarkably uniform character and chemical composition. Analyses compare closely with those from British quartz dolerites and tholeiitic rocks of the British Tertiary Province, with Karoo basalt lavas, Deccan traps and South American Gondwana dolerites. An average composition of four Spitsbergen dolerites was shown as follows: SiO2, 49.2; A1203, 14.4; Fe203, 3.4; FeO, 10.1; MgO, 5.4; CaO, 9.4; Na20, 2.0; K20, 1.0; H20, 1.6; TiO2, 2.9; P20, 0.2; MnO, 0.4; = 100%.

Submarine outcrops

4. 5.

north of Kong Karls Land, gently southward (1-3 ~ dipping strata with main fold south of Kvitoya; Kong Karls Land Structural High with intrusives; south and southeast of Kong Karls Land, structurally disturbed; around Storbanken sediments are flat lying; south of the Olga Basin is a major synform.

The distribution of Jurassic and Cretaceous deposits offshore on the northwest Barents Shelf was initially analysed from grab samples (Dibner 1968; Bjorlykke, Bue & Elverhoi 1978). Much of the shallow bedrock geology has been deduced from the analysis of Mesozoic clasts which occur in Late Quaternary sediments and which are believed to have been locally derived. Subsequently much seismic data has become available as well as information from shallow cores (e.g. Elverhoi & Lauritzen 1984; Gramberg & Pogrebitskiy 1984). The data were reviewed by Elverhoi et al. (1989) and Dowdeswell (1988). Nagy (1973) identified Oxfordian to Hauterivian macrofaunas including buchiid bivalves, belemnites and onychitids in dredged blocks from Svalbardbanken. Edwards (1975) recognized Helvetiafjellet-Carolinefjellet lithologies from blocks from central Svalbardbanken and Janusfjellet Subgroup lithologies on the northeast central part and more widely on the flanks. Bjaerke & Thusu (1976) listed Cretaceous and possible Jurassic palynomorphs from blocks on the south side of Spitsbergenbanken, suggesting the presence of Rurikfjellet and Carolinefjellet formations or their equivalents. Elverhoi et al. (1989) recognized widespread Rurikfjellet Formation especially in fine grained lithologies, although Jurassic and Cretaceous sandstones were more difficult to separate from those of the Wilhelmoya Formation. Early Cretaceous trace- and body fossilrich sandy limestones occurred more distally from the clastic sources, but indicated shallow marine conditions and showed affinities with the Tordenskjoldberget Member of Kong Karls Land. Sideritic cements in the limestones suggested a meteoric water origin of undetermined date. Feldspathic sandstones are comparable to those of the Kong Karls Land Formation and with the Helvetiafjellet Formation of Kvalvgtgen on the east coast of Spitsbergen and are related to the Kong Karls Land volcanics. Dolerites are particularly common northeast of Hopen. ,~rhus et al. (1990) described cored sections from the Bjornoya Basin/east Bjarneland Platform. Here a condensed marine sequence of latest Jurassic to Early Cretaceous (Volgian-Barremian) age was penetrated. Dating of the sequence was by buchiid bivalves which gave latest Volgian to Hauterivian ages (Buchia cf. unschensis, B. cf. volgensis, B. okensis, B. keyserlingi and B. cf. sublaevis) and 47 dinoflagellate taxa which gave Volgian to Barremian ages. Other bivalves, brachiopods, cirripedes and foraminifers were also recognised. Although Late Cretaceous sediments are not recognized in the northwest Barents Shelf, they are present under Cenozoic cover in the Nordkapp Basin, the Tromso Basin/Senja Ridge area, Bjornoy Basin and Hammerfest Basin in the southwest Barents Sea (Faleide, Gudlaugsson & Jacquart 1984). Late Cretaceous sediments are also known from Franz Joseph Land where a Cenomanian transgressive sandstone occurs, and in the northeast Barents Sea (Dibner 1970, 1978). Erratics containing inoceramid bivalves have been brought onshore in southern Novaya Zemlya (Cherkesov & Burdykina 1981).

EASTERN SVALBARD PLATFORM

5.4

Northeastern Spitsbergen, Wilhelmoya and Hinlopenstretet

The Lomfjorden Fault Zone is a convenient western boundary to this area which is considered in three parts (1) the Permian-Carboniferous outcrops east of that fault zone from Lomfjordenhalvoya, through Olav V Land to Akademikerbreen. (2) The Triassic strata of eastern Olav V Land and Wilhelmoya (3) the islands of Hinlopenstretet (and southeast of Wilhelmoya). Much of the mainland is ice-covered and the islands are separated by water. The result is that the three contrasting rock types: Mesozoic dolerites; Mesozoic strata (mostly Triassic); Permo-Carboniferous strata while easy to identify, even from a distance, are hardly anywhere exposed in contact. Moreover, the area is relatively remote and while the rocks were long known in the broad outline indicated above it was only since about 1953 that more detailed studies became available. From the above distribution of three rock types the early maps of this area were constructed e.g. by Nathorst (1910), Frebold (1935), Orvin (1940). The western limit treated in this section approximates the eastern limit of the early Cambridge exploration of Ny Friesland (e.g. Harland & Wilson 1956 and Harland 1959). Indeed the complex fault pattern in Lomfjordenhalvoya with inliers of Hecla Hoek surrounded by Permian and Carboniferous outcrops is separated in this treatment according to age. Hence there are two distinct terranes, Permo-Carboniferous and Triassic separated by wide expanses of ice except west of Hinlopenbreen and at the southwestern head of Negribreen.

5.4.1

Northeastern Spitsbergen: Permo-Carboniferous terrane

The earliest detailed succession is due to Cutbill (1968). His maps of this terrane, largely followed on a smaller scale by Lauritzen & Worsley (1975), are redrawn in Fig. 5.2, based on earlier C.S.E fieldwork and the later work in conjunction with Amoseas. Cutbill's stratigraphic scheme, modified only according to rank of units to be consistent in this volume with SKS recommendations, is as follows. It is based on his measured sections at Polarisbreen, Komarovfjellet and Malte Brunfjellet. Lauritzen & Worsley from work in the Lomfjorden area added further sections at Mjolnerfjellet and Eremitten and revised some of Cutbill's conclusions. The following account is intended to combine and summarise those data from different sections and interests: Cutbill giving biostratigraphic data and Lauritzen & Worsley lithological.

Tempelfjorden Group. As in most of Spitsbergen, the sole representative of the Tempelfjorden Group is the Kapp Starostin Formation. Kapp Starostin Formation, 140+ m (mid to Late Permian). Complete exposure was nowhere recorded; but at Eremitten more intermittent resistant beds comprise about 50% of the succession where a highly siliceous biomicrite bed is overlain by silty shales of presumed Triassic age. Typical lithologies reported are sandy biosparites in which the bioclastic fraction is dominated by brachiopod debris. Glauconite was seen in most specimens suggesting correlation with the Hovtinden Member.

Gipsdalen Group Gipshuken Formation. 140-179 m (Artinskian). Similarly perhaps less than half of the succession is exposed with the harder beds only being described, the most distinctive rock being a brecciated, cavernous dolostone suggestive of evaporites and dolomitic micrites. Wordiekammen Formation. This carbonate unit extends from the Central Basin with similar facies but is somewhat thinner. Tyrrellfjellet Member. 100 to c. 130m. (Asselian & Sakmarian). The upper part is poorly exposed and may be calcareous flaggy sandstone and the main and lower part is of elastic dolostones. Rugofusulina arctica, and Schwagerina anderssoni were recorded at the base. Cadellfjellet Member. c. 40 m (Gzhelian) More of this unit is exposed and largely sandy limestone and biomicrite, the latter containing Quasifusulina longissina and Montiparus montiparus. Malte Brunfjellet Formation. 60-70m (Late Moscovian). Complete sections are exposed and comprise biomicrites in the main upper part with fusiline faunas and calcareous sandstones in the lower part Beedeina

77

rockymontana, Wedekindellina dutkevichi, Pseudostaffella sphaeroidea are characteristic. Cutbill suggested that this, his Minkinfjellet Formation, represents a marine transgression because there appears to be no equivalent to the Ebbadalen Formation here. It does, however, occupy a basin related to the Lomfjorden Fault Zone and is so distinguished from the Minkinfjellet Formation of the Central Basin.

Billefjorden Group Mumien Formation. A basin equivalent of the Mumien Formation is present, but no representative of the lower (Horbyebreen) formation of the Billefjorden Group is recorded so that the succession is not only thinner but less complete than in the Billefjorden trough. Cutbill recorded only about 40 or 50 m of sandstone beneath his Minkinfjellet Formation resting on Hecla Hoek strata and none at Malte Brunfjellet. Lauritzen & Worsley argued for a greater thickness, partly on the basis of observations in the Lomfjorden area and partly by reinterpreting as Mumien Formation the lower part of Cutbill's Minkinfjellet Formation. The argument seems reasonable so that about 100 m is suggested. The formation contains spores of the Aurita zone assemblage (Playford 1962/63) suggesting a Visean (and possibly Serpukhovian) age.

5.4.2

Northeastern Spitsbergen: Triassic terrane

This terrane was originally almost u n k n o w n territory, and previously referred to as Terre Glac6e Russe (see Fig. 1.7), has been included in the relatively newly named Olav V Land. It is largely dominated by an ice sheet with glaciers draining into the sea through Triassic hills at its margins. Its western boundary is the range of high mountains of Hecla Hoek rocks and the strip of Permo-Carboniferous rocks. It so happens that the two highest mountains to the east are at Hellwaldfjellet and Wilhelmoya. These preserve Rhaetian and Jurassic strata in their tops and so have received more attention. Accordingly these two areas are reported in the Section 5.4.3. The southern boundary is at Negribreen, the largest glacier reaching the sea in Spitsbergen. Backlund (1908) traversed the ice from north of Negribreen westwards to Nordenski61dbreen (Storfjorden to Billefjorden) and Holland (1961) reconnoitred the southern margin of Negribreen southwestwards through to Tempelfjorden similarly traversing central Spitsbergen at its narrowest. At northern Hahnfjella, south of the Negribreen outlet, Holland recorded a Triassic succession which, although outside the terrane as defined, may be the only measured section in the general area. Abbreviating somewhat, the succession was recorded thus: 9 m (at summit) thin bedded blue shales with brittle fossiliferous limestone nodules with Arctoceras (cf. A. O'bergi or Flemmingites; Halobia cf. zitteli, Daonella cf. lindstomi etc.; 12m alternating blue shales with concretionary limestones; 12 m paper thin blue shales with occasional iron-stained limestone nodules; 19m blue shale down to limestone shales interbedded with limestone and limestone concretions; 16m thin grey shales; 68 m grey and grey and black shales with Arctoceras sp. and Keyserlingites sp; 46 m thin bedded, grey fawn and grey baked shales to dolerite intrusion about 120m a.s.1. The lithologies and fossil indentifications by L.F. Spath would correlate with the Botneheia and Sticky Keep formations (Sassendalen Group).

5.4.3

Wilhelmoya and Hellwaldfjellet

The importance of Wilhelmoya was perhaps first realised by de Geer (1923) who reported a succession through Early Kimmeridgian, late Lias, latest Triassic and Carnian strata. This was used and discussed by Frebold in his 1935 synthesis and notably Arkell (1956). From a visit by an Oxford party in 1951 Holland (1961) described a sequence of 13 beds. The rocks were described in detail but the fossils identified, mostly bivalves, left the ages indeterminate. The relation between this work, that of De Geer and the opinion of

78

CHAPTER 5

Fig. 5.2. Geological map of eastern Ny Friesland, with representative cross-sections, showing the distribution of Carboniferous and Permian deposits (rearranged after Cutbill 1968).

EASTERN SVALBARD PLATFORM Frebold were discussed. The undoubted Jurassic above Triassic strata here led Sandford to postulate Jurassic rocks at the top of the Triassic succession in Nordaustlandet. In 1961 the section was reconnoitred by a party commissioned by American Overseas Petroleum Limited (Amoseas) and was noted in Buchan et al. (1965, Section JDL21). Klubov (1965) first reported Rhaetian (beds 23-27) in his succession ranging from Carnian to Kimmeridgian rocks from the top of Wilhelmoya. However, his measured succession for the island is not supported by later work possibly because he did not take account of land slips. Worsley (1973), from visits in 1970 and/or 1971, described the uppermost strata and made a case for a new Wilhelm~ya Formation to include similar strata in Hopen and the Brentskardhaugen Bed of Spitsbergen. Smith (1975) described the whole in situ section on the island from a survey with CSE in 1969. He incorporated Worsley's new unit name but as a member within the De Geerdalen Formation which had already been defined to include the Brentskardhaugen Bed at the top. Accordingly in Wilhelmoya and Hellwaldfjellet he named the rest of the De Geerdalen Formation, i.e. above the Tschermakfjellet Formation, as another member (Uleneset) 254 m thick. However, the case is argued by Worsley & Heintz (1977) that the De Geerdalen Formation should be redefined and reduced so as to allow this new formation above it. A consequence is that the reduced De Geerdalen Formation is indeed Smith's Ulaneset Member which no longer needs that name, the Kapp Toscana group thus comprising the rocks as originally defined but in three rather than two formations. Both Worsley and Smith visited similar successions from Wilhelmoya and Hellwaldfjellet on the mainland to the southwest. Smith described the whole sections and Worsley the proposed Wilhelmoya Formation. The following description combines the two.

Wilhelmeya and Hellwaldfjeilet. The Hellwaldfjellet section on the mainland is similar, Hellwaldfjellet being only 35 km to the south, so the description is combined, where there are differences the symbols W and H respectively identify which section is referred to. Smith (1975, pp. 486-487) plotted both sections in full.

Agardhfjellet Fm. Black shales with ammonites of Oxfordian to Kimmeridgian age are separated (W) or capped (H) by a dolerite sill. Ammonites from these (W) include tenuilobatus zone of Arkell (1956, p. 505) and would correlate with middle Agardhfjellet Member to the east (Parker 1967). Klubov (1965a, 1970) reported a bed of clay with belemnites and two foraminiferal assemblages: Bajocian-Bathonian and Callovian. His exposure probably represents a slipped mass amongst others from the Agardhfjellet Formation. The total thickness of sediments above is about 10 m (W) and 35 m (H). Wilhelmoya Fm Turalingodden Mbr, 60m (W) 54m (H), named from the slopes above Tumlingodden, mainly comprises friable fine-grained yellowish grey sandstones. The boundary between the Wilhelmoya and Janusfjellet formation is marked by a thin conglomerate of fine quartz pebbles (H). The top 10 m has pockets of phosphorite nodules including Toarcian fossils similar to those found in the fauna of the Brentskardhaugen Bed. 28m sandstones with a basal pebble bed and winnowed fossils (including belemnites) but absence of plant fossils contrasts with the lower sandstone. A 4 m bed of clay 30 m from the base. Thin black coal lenses and black shales occur within the lower 28 m with tree trunks up to 20cm thick in a metre section are preserved within sandstone concretions. Thin sandstone layers and pockets of quartz and chert pebbles. About 10m from the base is a cliff of well-consolidated sandstone with tabular cross-bedding which indicates westwards sediment transport. Transitional Mbr, 33 m (W) 5 m (H). Dark yellow friable flaggy siltstones with intercalated beds of more resistant cliff-forming olive flags (which weather purple) dominate the upper part and decrease downwards. Harder beds contain mud flake conglomerates, mica and plant debris. The upper boundary is obscured because of the soft overlying beds. Bjornbogen Mbr, 19m (W) 33m (H), named for the bay on the south of Wilhelmoya, is formed of thick dark grey shale which contains winnowed

79

interbeds of plesiosaur bones. Clay ironstones occur with a rich bivalve fauna. Basal Mbr, 7 m (w), is of sandstone. The base of the formation (W only) is marked by a bed with pebbles, sandy limestones, phosphorites and quartzites in a ferruginous silty limestone matrix (W & H). For reference purposes it would have been more convenient to include the Transitional Member as a division in the Tumlingodden Member and the Basal Member as basal beds of the Bjarnbogen Member and this was done later. De Geerflalen Fro, 384 m (W), 401 (H). The thickness includes a 10 to 30 m dolerite sill. The rocks were described by Klubov (1965). They consist predominantly of siltstone and fine-grained sandstone with occasional beds of better-cemented, sometimes calcareous, coarser sandstone. The upper 154 m contains several horizons of shell fragment limestone. Carbonaceous plant material and thin coal seams occur in the lower 200 m. At the base of the Formation is a prominent sandstone bed above the siltstones and shales of the Tschermakfjellet Formation. Invertebrate fossils are rare. Klubov recorded bivalves Lima, Megalodon, Ostrea and Mytilus of shallow marine or non-marine conditions and suggested a Norian-Carnian boundary 221 m from the base of the formation. However, Smith's palynological evidence suggests that the strata are largely Norian. The formation at Hellwaldfjellet is generally sandier, less consolidated and without shell fragments and so less distinct from the Wilhelmoya Fm, (Smith 1975). Of 20 or more samples through the whole succession investigated palynologically in 1961 and 1969 only three gave significant results and these came from the De Geerdalen Formation roughly 337m 166m and 73m from the base of the formation. They were all concluded to be of Norian age (Smith 1975) and to compare with the lower part of the Iversenfjellet Formation of Hopen. Tsehermakfjellet Fm 34+ m to SL (W), ?70 m (H). Siltstones with siderite concretions and Halobia bivalves occur in a disconnected outcrop (H) and from near the base (W) Klubov reported Nathorstites spp. and Halobia zitteli, and higher up Sirenites cf. nanseni, all of which confirm a similar age for the strata. A discussion of these and other finds with conflicting assessments conclude with an Early Carnian estimated age for the formation in Withelmoya (Smith 1975). Botneheia Fro. An exposure of a few metres at the shore by Hellwaldfjellet of silty shale yielded ammonites in 1969: ?Gymnotoceras and ?Hollandites with bivalves indicating an Anisian age (Smith 1975).

5.4.4

Islands of Hinlopenstretet

Whereas Wilhelmoya preserves a Mesozoic succession with incidental dolerite sills, all the other (much smaller) islands, except one between Spitsbergen and Nordaustlandet, have been eroded to the extent that only their igneous rocks are seen. The exception is the largest of the islands, Wahlbergoya where two Permo-Carboniferous outcrops appear on the 1:500 000 map of Hjelle & Lauritzen 3G (1982). Moreover, Korchinskaya (1972a) identified the Arctoceras blomstrandi zone of Spathian age on the island. Tyrrell & Sandford (1933) described many of the known dolerite occurrences and noted that opposite the largest sill in the coast south of Kapp Fanshawe are islands which may well be an extension of it. They suggested that these are fragments of a huge laccolith, possibly of cedar tree type. On and off the Nordaustlandet coast are the massive intrusions at Diabastangen (Hyperite Point) and the Gylden islands. Some dolerite islands further south are surrounded by deep water and form an irregular incomplete ring. This and other arrangements suggest that the islands may be relics of vertically sided intrusions and not irregularly sunken sills (Tyrrell & Sandford 1933, p. 292).

5.4.5

The structure

The dominant feature of this area is the western boundary which is the Lomfjorden (Agardhbukta) Fault Zone and the Hecla Hock

80

CHAPTER 5

synclinorium which is occupied by the strait separating Spitsbergen and Nordaustlandet. Otherwise the platform strata are generally flat-lying.

5.5

Southwestern Nordaustlandet

Nordaustlandet is mostly covered by ice and the exposures are mainly coastal. The platform succession is exposed only in the southwest sector of the island, almost all south of Wahlenbergfjorden. The same three rock types are distinctive from the air namely the black dolerite intrusions, the less resistant dark coloured Triassic strata and the paler harder Permian and Carboniferous strata. Figure 5.3 summarizes the outcrops from a number of independent investigations.

5.5.1

Earlier work

Because it was relatively easy to distinguish Triassic and Permian and/or Carboniferous strata the approximate occurrences were

already plotted as on the maps of Nathorst (1910), Kulling (1934), Frebold (1935) and Orvin (1940). However little was published of the stratigraphy till later. Triassic material from the earliest known outcrops at Torellneset collected in 1931 comprised Saurian remains, bivalves and ammonites (Kulling 1932, 1934). The molluscs were identified by E. T. Tozer and reported briefly by Tozer & Parker (1968) and more fully later (Tozer 1973). These identified late Scythian and Anisian ages. Oxford parties on expeditions to Nordaustlandet in 1923 (Sandford 1926), 1949, 1951 and 1953 described both Hecla Hoek and younger rocks (Thompson 1953; Holland 1961). Of the latter the reports of observations by glaciologists interpreted by Sandford (1963) establish a clear unconformity at Idunfjellet where Late Carboniferous and Permian strata rest on Hecla Hoek rocks. This together with a small outcrop of ?Carboniferous sandstones at Brageneset to the west is the only occurrence of the younger rocks north of Wahlenbergfjorden. South of that fjord and at its mouth De Geer (1923) had reported 200m of Productus Limestone overlying 42 m of Spirifer Limestone. Holland, in a posthumous work edited by Sandford (1961), described Mesozoic and Late Paleozoic rocks in both northeastern Spitsbergen and Nordaustlandet. These Permo-Carboniferous strata

Fig. 5.3. Geological map of southwestern Nordaustlandet showing the known extent of Phanerozoic outcrops. Key to numbered localities: (1) Bodleybukta; (2) Eltonbreen; (3) Ericabreen; (4) Mariebreen; (5) Palanderbreen; (6) Rosenthalbreen; (7) Svartberget; (8) Torellnesfjellet; (9) Winsnesbreen. Compiled from Geological Map of Svalbard 1:500 000 sheets 3G (Hjelle & Lauritzen 1982) and 4G (Lauritzen & Ohta 1984) and from SKS Upper Carboniferous Report Map 3a (Dallman et al. 1996).

EASTERN SVALBARD PLATFORM

Kapp Toscana Grp (?) Wilhelmoya Fro. It is not impossible that this formation is represented at the highest part of the succession at Torrellnesfjellet which was inaccessible to Lowell (1968) owing to ice cover. Sandford in Thompson (1953) and in Holland (1961) suggested the possibility that the highest strata might be Jurassic, on the basis of the presence of black shales at Torellnesfjellet and lithological comparison with samples from Wilhelmoya. If this were so, however, the De Geerdalen Formation might be exceptionally thin. De Geerdalen Fm. 40?+50m. Lowell 1968 described the top of his succession as largely sandstone scree: grey brown, some slightly greenish, faintly limonitic calcareous, finely laminated and platy. Sassendalen Gp Barentsoya Fro. 118 m Lowell 1968 described a uniform sequence of grey shale with thin platy beds of siltstone weathering brown to yellow which are calcareous with 'occasional fontainbleau' structure (i.e. with matrix of larger enveloping calcite crystals). He reported the presence of brachiopods. Cutbill (CSE) had already identified these rocks as belonging to the Sassendalen Group. The name Barentsoya Formation is applied here because, with the exception of some interbedded limestone with chert in the lower 20m the whole was described as undifferentiated. In so far as the three formations, which define the Sassendalen Group in Central Spitsbergen, are not distinctive here, the Barentsoya Formation is applied from Barentsoya and Edgeoya where the three formations also are not readily distinguished. Kulling's collection was from two levels and he suggested that the upper level was the Upper Saurian Niveau. The underlying level 'Daonella Niveau' was exclusively of bivalves (Posidonia arenea Tozer) which is restricted to the later Spathian Zone (Keyserlingites subrobustus zone). This correlates with the Sticky Keep Formation of Spitsbergen. Fossils from Kulling's upper horizon of typical Botneheia facies include nine ammonite species and the ichthyosaur Phalardon nordenskioldi was identified by Stensi6 (Kulling 1932). These give a certain middle Anisian age and possibly an Early Anisian age also. In any case they confirm correlation with the Botneheia Formation in Spitsbergen. Tempelfjorden Gp Kapp Starostin Fm. Lauritzen (1981) distinguished two limestone members in the otherwise siliceous sequence, the basal Voringen Mbr (recognised elsewhere), and the Palanderbukta Mbr (Fig. 5.4). This led to the naming of the remainder of the alternating normal siliceous sequence with the names from central Spitsbergen thus: Hovtinden Mbr: 27 m of yellow and grey cherts at the top with subordinate sandstones; glauconitic. Then predominantly sparitic limestones, in places dolomitized, with chert bands and nodules. Palanderbukta Mbr: 17.5m characterized by glauconitic and fossiliferous limestones, with pure chert beds. Svenskeega Mbr: 37.5m of chert-dominated sequence with relicts of calcareous beds or nodules. Intraformational conglomerates and erosion horizons at the top.

in N o r d a u s t l a n d e t were described f r o m m a n y localities and m a p p e d as such with a large o u t c r o p occupying m o s t of Gustav A d o l f L a n d (south of W a h l e n b e r g f j o r d e n ) and excepting the Triassic o u t c r o p extending eastwards a n d inland f r o m Torellneset. There the succession was described generally as (4)

Upper chert, Marble and Limestone Series with Stenopora ramosa 30+ m (3) The Rough Limestones, with S. ramosa, Spiriferella cf. lita etc. 40 m. (2) The Cliff Limestones, with Spiriferella cf. polaris, etc. 55 m (1) The Calciferous Sandstone Series with Productus (Horridonia) timanicus, 45 m. Base not seen. Fuller descriptions of each of these units was given with fossil lists for each but lacking detailed maps or sections this pioneer reconnaissance is difficult to follow. The Mesozoic results were largely published in T h o m p s o n (1953) with a postscript by Sandford. The next field w o r k was in the early 1960s w h e n CSE c o o p e r a t e d with A m o s e a s using helicopter support. Cutbill extended his study of P e r m i a n and C a r b o n i f e r o u s stratigraphy. H e n o t e d Triassic successions comprising u p p e r m o s t strata which he regarded as K a p p T o s c a n a and a lower 150m of shales as Sassendalen G r o u p above K a p p Starostin (especially Voringen M e m b e r ) overlying the G i p s h u k e n F o r m a t i o n , with basal Hftrb a r d b r e e n M e m b e r (Cutbill & Challinor 1965). Lowell (1968) of A m o s c a s filled in m o r e detail a n d m e a s u r e d two Triassic and P e r m i a n sections as well as giving a m o r e detailed o u t c r o p map. Lauritzen (1981), w o r k i n g f r o m Wahlenbergfj orden, addressed only the Late Paleozoic succession a n d with m o r e m e a s u r e d sections. This resulted i.a. in extending the age of the lower p a r t of the succession back to M o s c o v i a n time. His w o r k was also incorporated in the 1:500 000 geological m a p 4 G (Lauritzen & O h t a 1984). M a n g e r u d & K o n i e c k i (1991), investigating the P e r m i a n rocks of N o r d a u s t l a n d e t palynologically, r e c o r d e d sixty forms ranging mostly in the ?Gipsdalen G r o u p . H o w e v e r , little was a d d e d to previous k n o w l e d g e as to their age. Nevertheless a useful synthesis o f m e a s u r e d sections by M. B. E d w a r d s with those of Lowell & Lauritzen (already m e n t i o n e d ) shows the position of their samples. A t the same time an i m p r o v e d sketch m a p of W a h l e n b e r g e t and P a l a n d e r b u k t a distinguished clearly the T e m p l e f j o r d e n a n d Gipsdalen G r o u p outcrops.

5.5.2

81

Stratal succession

K n o w l e d g e has c o m e s o m e w h a t piecemeal. The succession is s u m m a r i z e d in Fig. 5.4.

Nordaustlandet Cutbill & Challinor (1965) KAPPTOSCANA (?~chermakqtFm)

This work (following SKS 1996)

Lauritzen 1981

Lowell1968

De Geerdalen Fm

KappToscana Fm

Barentsoya Fm

SASSENDALEN GROUP (undifferentiated)

Kapp

Kapp

Starostin

Starostin

Svenskeegga Mbr

Fm

Voringen Mbr

Palanderbukta Mbr

Kapp Starostin

Svenskeegga Mbr

Fm

Gipshuken Fm Zeipelodden Mbr

Carbonate Unit

DICKSON LAND

Idunfjellet Mbr Nordenski61dbreen

H&rbardbreen Mbr

TEMPELFJORDEN GP

Voringen Mbr

Gipshuken Fm Gipshuken Fm

SASSENDALEN GP

Hovtinden Mbr

Hovtinden Mbr

Fm

KAPP TOSCANA GP

Fm

Idunfjellet Fm ]

Wordiekammen Fm

H&rbardbreen H&rbardbreen Mbr L Fm

SUBGP

CAMPBELLRYGGEN SUBGP J

Fig. 5.4. Stratigraphical schemes for Permian and Triassic units of Nordaustlandet.

82

CHAPTER 5

Voringen Mbr: 9 m of sandy biosparite with conglomerate layers. Erosion surfaces, cross-bedding and bioturbation are common. Coal fragments occur at the base, and fossils are abundant. It rests on a clearly eroded surface of Gipshuken Fm. Lauritzen interpreted the Voringen Mbr as a transgressive shallow marine unit, probably near-shore as indicated by erosion surfaces. The change to cherts indicates a switch to an open shelf environment and hence subsidence, but this reverses at the top and into the Palanderbukta Member which is once again a shallow marine unit with periods of erosion. Basin deepening occurred at the transition to the Hovtinden Member with biosparite deposition and then further cherts, which are commonly spiculitic.

Gipsdalen Gp Gipshnken Fro. Cutbill & Challinor (1965) described the Gipshuken Fm with the H~trbardbreen Mbr (Formation) at its base. Lowell (1968) followed this section referring to the rocks between that member and the Kapp Starostin Fm as the Carbonate Unit. This might have merited a separate name had not Lauritzen (1981) shown that biostratigraphically the lower part of the Carbonate Unit belonged to the Nordenski61dbreen Fm (Wordiekammen + Minkinfjellet fms) and named it the Idunfjellet Mbr (see below). Thus the Gipshuken Fm is equivalent only to the upper part of Lowell's Carbonate Unit. Lauritzen (1981) described the formation from Zeipelfjella (Fig. 5.5.2) and Zeipelodden in the Wahlenbergfjorden area. The formation reaches a maximum thickness of 121 m there, with a clearly identifiable member (the Zeipelodden Mbr) at the base. The member is a 8 m thick unit of limestone breccias and laminated algal limestones with algal mats, crusts and chert nodules. The remainder of the formation consists of well-bedded limestones and dolomites with chert nodules. He interpreted the formation as a lagoonal deposits with some tidal influence, especially the basal member which was probably intertidal. Mangerud & Konieczny (1991) investigated the palynology of the formation in the area. Although the middle and upper parts did not yield age diagnostic forms, the lower part was given a Sakmarian to Artinskian age along with the underlying Idunfjellet Fm. Idunfjellet Fm (Lauritzen 1981) Up to 150m thick, the Idunfjellet Fm consists of limestones and dolostones with minor sandstones (Fig. 5.4). It is the northeastern equivalent of the Wordiekammen Fm. The carbonates contain chert nodules; the sandstones cross-bedding and intra-formational conglomerates. The formation was deposited on an open marine shelf, some parts in the inter-tidal zone, with a terrigenous input from a nearby land mass. Periods of non-deposition were common, as the formation represents the entire late Carboniferous to early Permian time-span. Fossils have mostly been destroyed by dolomitization; however some from the base indicate a Moscovian age for that level and palynomorphs indicate a Sakmarian-Artinskian age. The 135.4 m thick type section consists of limestones and dolomites with a quartz content varying from 6 to 21%, especially in the lower l0 m, which are well-bedded sandy dolostones. The sand is the same grain size as in the Hftrbardbreen Fm below. Chert nodules are abundant in some beds, which preserve bioclastic remains. Silicification tends to follow certain horizons and the cherts are sometimes associated with crusts of hematite and thin layers of goethite. Erosive sandstones occur, containing thin intraformational conglomerates and cross-bedded units. Dolomitization has destroyed most fossil fragments, except in some horizons where they are abundant, especially 10m above the base in a distinctive partly dolomitized and silicified biosparite which contains a variety of fossils. Brachiopods, gastropods, echinoderms, cephalopods, foraminifers and ostracodes occur. The biosparite horizon ! 0 m above the base has been dated as Moscovian on the basis of the foraminifera Palaeojusulina trianguliformis and several Bradyina species (Lauritzen 1981). Palynological investigations of the formation indicate a Sakmarian to Artinskian age (Mangerud & Konieczny 1991), and hence it would appear to have a long time span. This is consistent with the common erosion surfaces and intraformational conglomerates, which imply reworking and periods of non-deposition. Also, the overlying Gipshuken and Kapp Starostin fms have been correlated with the same formations in the rest of Svalbard on the basis of lithology. Thus, the Idunfjellet Fm and the basal Hftrbardbreen Fm together appear to represent the Wordiekammen and Minkinfjellet fms respectively. Lowell (1968) described his Carboniferous unit (Idunfjellet and Gipshuken Fro, i.e. above the Dickson Land Subgroup) as being a condensed sequence compared with the much thicker equivalent succession in Central Spitsbergen. This argument is strengthened by the large age span for these rocks as indicated above. However, Lowell followed Cutbill when including these rocks within the Gipsdalen Formation.

Fig. 5.5. Sketch map of Svenskoya, Kongsoya and Abeloya (redrawn with permission of Cambridge University Press from Smith et al. 1976).

H~rbardbreen Fm. This unit at the base of the Permo-Carboniferous sequence in the Nordaustlandet area, was, in the absence of datable fossils, assigned to the base of the Gipshuken Fm by Cutbill & Challinor (1965). Lauritzen (1981) redefined it, after detailed studies, in the section at Idunfjellet on the opposite side of Wahlenbergfjorden from H~rbardbreen. It lies conformably below the Idunfjellet Mbr and its base is a strong angular unconformity with pre-Devonian (Hecla Hoek) rocks. There is evidence that the basal conglomerates are laterally replaced westwards and on the south side of Wahlenbergfjorden by sandstones (e.g. at Hftrbardbreen). The formation is a 15.5 m thick unit, consisting of light, yellowish-grey, fine-medium quartzitic sandstones with some conglomeratic horizons. Crossbedding is locally present and the whole unit becomes finer upwards. There is a basal conglomerate 8m thick which unconformably overlies the preDevonian peneplain surface. The clasts are mostly of dolomitic mudstones,

Fig. 5.6. Sketch map of Svenskoya showing principal topographic features and geology (redrawn with permission of Cambridge University Press from Smith et al. 1976).

EASTERN SVALBARD PLATFORM but also clasts of the underlying red mudstone commonly occur. The conglomerates appear to be locally developed, with lateral replacement by sandstone. The formation has no fossil record, but a Moscovian transgression has been described in Ny Friesland and central Spitsbergen (Cutbill & Challinor 1965) and this unit may therefore be the lateral equivalent of the base of the Campbellryggen Subgroup there.

5.6

Kong Karls Land

Kong Karls Land is a group of three main islands (Fig. 5.5) and many smaller ones and is the easternmost substantial land in the Svalbard archipelago. It is generally surrounded by sea ice even through the summer so that visits have been limited either by ship in favourable seasons or more recently by helicopters from icestrengthened ships. Apart from the ubiquitous Quaternary cover the rocks are entirely Mesozoic. Svenskoya is the westernmost island, 20 km by 6 km (Fig. 5.6). Most of the island is of beach deposits but there is an axial N-S ridge the length of the island rising from Kukenthalfjellet, 180 m in the south to Dun~rfjellet, 250 m in the north. The main island Kongsoya (Fig. 5.7) is central and about 40 by 8 km, but of irregular outline. It divides naturally into five terrains from west to east (1) a western complex of fiat topped hills, (2) a neck of low ground, raised beaches and blown sand, (3) a low lying plain of basalt, (4) a low hilly area of basalt with a small ice cap, Rundisen, and (5) one main hill (Johnsenberget) sloping down from 240 m to low cliffs at the east coast. The eastern irregular island, Abeloya is not more than 4 k m across, mostly less than 5 m above sea level and formed of basalt.

5.6.1

Apart from occasional visits the first, and for many years the only, proper geological investigation was by the Swedish expedition of 1898 led by Nathorst (1901, 1910; Pompeckj 1899; Bliithgen 1936) (Fig. 5.8). This gave a topographic base and a geologic outline. The uppermost strata are basalts and plant beds. These were shown to truncate and overlie three blocks, normally faulted, from west to

KONGSE

east: (1) Eastern Svenskoya of Volgian, Kimmeridgian, Oxfordian strata; (2) A central block (eastern Svenskoya and western Kongsoya) of Callovian over Bathonian strata and (3) the main body of Kongseya of Valanginian, Late and Early Volgian, Kimmeridgian strata. In 1930 the Norwegian expedition to Franz Josef Land in passing confirmed that Abeloya was entirely igneous. A new era in geological exploration of these often ice-bounded islands began with the use of helicopters. In 1969 a Cambridge reconnaissance of the islands of eastern Svalbard was supported by Norske Fina. Sections were recorded at most cliff exposures of Kongs Karls Land and the structure and stratigraphy were described (Smith et al. 1976). Norsk Polarinstitutt geologists visited the islands in 1973 and they found an exposure lower than previously recorded in northwest Kongsoya (Worsley & Heintz 1977). This was supplemented by palynostratigraphy (Bjaerke 1977, Bjaerke & Dypvik 1977). The material collected in 1969 continued to yield results (e.g. Rawson 1982; Doyle 1986, 1987; Doyle & Kelly 1988; Ditchfield, 1997). The rock units of Kong Karls Land were defined by Smith et al. (1976) and related to those of Pompeckj (1899), Nathorst (1901) and Bliithgen (1936), with one addition and one modification proposed by Worsley & Heintz (1977) as shown in Fig. 5.8. Their distribution is shown on the maps of Svenskeya (Fig. 5.6) and Kongseya (Fig. 5.7). The strata were described and measured in 15 or more sections (Smith et al. 1976) Because of the variety of facies including lavas even within one island the units were named independently as members within three distinct units. The Kong Karls Land, Kongseya and Svenskoya formations. However the Wilhelmoya Formation (Worsley 1973) has priority over the name Svenskoya and is applied here.

5.6.2

Earlier work

83

Stratal succession

Adventdalen Group. The correlation of the principal stratigraphic sections of Svenskoya are given in Fig. 5.9 and of Kongsoya in Fig. 5.10. Kong Karls Land Fm. This is the uppermost unit comprising plant bearing sandstones interbedded with lavas. It approximates stratigraphically to the Helvetiafjellet Formation in Spitsbergen which also contains evidence of vulcanicity and has been taken to be of Barremian age (Parker 1967).

A ~

Ose~

Notcl~s~ynlim

Kaoo Otnva

..

0 I

~

5 =

i

10 k m I

, - -

Fig. 5.7. Sketch map of Kongsoya showing principal topographic features and geology (redrawn with permission of Cambridge University Press from Smith et al. 1976).

84

CHAPTER 5

Schemes of rock units Early age estimates

Pompeckj & Nathorst Smith, Harland, Hughes & Picton 1976 with proposals* by Worsley & Heintz 1977 1899 1901 KONG KARLS LAND

SVENSKOYA

Current age estimates

KONGSOYA ~ X,BELWESTERN EASTERN OYA

13 basalt Kong

Member

H&rfagrehaugen Member

Johnsenberget Member

Karls

sandstone

sandstone

sandstone

Land Formation

65.5 m (Beds 10 & 12)

14 m (Beds 10 & 12)

30 m (Bed 10)

K0kenthalfjellet

12 plant bearing layer with Phoenocopsis Neocomian

11 basalt

c0 Barremian

10 plant bearing layer

Late

Volgian I=nrly Early Kimmeridgian

g Bed with Aucella keyserlingi 8 Bed withAucelta fischeriana and A. volg,,ensis eto 7 Bed withA, pallasi 6 Bed with Cardioceras. andAucella sp.

s./.

Tordenskjoldberget Member limestone 30 m (Bed 9)

~" ~ c

Kongs~ya Formation

5 Bed with A. bronni vat. lata Oxfordian Middle & Late 4 Bed with Cadoceras and belemnites Callovian - 3 Bed with Macrocephalites (=Arcticoceras Early arcticus) & belemnite~ Late

Fig. 5.8. Stratigraphic schemes of rock units with age estimates. In this work the units are described as by Smith et al. (1976) and accepted as shown, but with the later proposals by Worsley & Heintz 0977) for the Wilhelmeya Formation (rather than the Svenskoya Fm) and the Kapp Koberg Member.

Bathonian

Bed with Pseudomonotis etc.

sand and sandstone

no fossils

Dunerfjellet Member

upr

shale

Iwr

(upper & lower) 6O m (Beds 3-7)

~ ~

~ ~

~ = "~ ~

~

~

~

Nordaustpynten Member

Kimmeridgian Oxfordian Callovian Bathonian

?50 _m_(_Be_d_ 9_L _ shale

?150 m (Bed 8)

s.I.

Bajocian

Member clay 75 m (Bed 4) Sjergrenfjellet Member

sandstone (Beds 1 & 2)

sandstone

Arnesodden Bed

*Kapp Koberg Member

shale

Hauterivian Valanginian Berriasian Tithonian

Passet

Mohnhegda Member

_

~

Retziusfjellet Member shale 75+ m (Beds 6-7)

Upper part of Kongseya Formation

Aalenian Toarcian Ptiensbachian ?Sinemurian ?Hettangian

Rhaetian

MOHNH~GDA k'0KEI,fI'HALFJELLET

DUNI~RFJELLET

bQsatt

T

?-"v

i

7t i

200 m

-r T

i

u

x

!":" ," ;

:...i/..:.1 K O W - n t ~

9 , -~ oi

Fig. 5.9. Correlation of the principal stratigraphic sections on Svenskaya (redrawn with permission of Cambridge University Press from Smith et al. 1976).

Lend Fm

~

Fm

Member

Fm

;.4

\1

100

KongKor~

Member

5o 0

i

2

3

4

I

I

I

I

I

5kin I

ArnesenoddenBed

It includes units 10 to 13 of Nathorst but there are more lavas than he listed. The three members each represent the entire formation in a particular area. The reference section at Mohnhogda in Svenskoya may be taken as the type for the Formation. Kiikentbalfjellet (sandstone and basalt) Mbr, 65 m at Ktikenthalfjellet the southernmost mountain of Svenskoya comprises a variable sequence of mainly arenaceous sediment with basalt layers which are units 10 and 12 of Nathorst (1910, p. 362). 5.1 m basalt, lava flow, vesicular in the basal 2 m; 6.1 m sandstone with some shale and compressed plant remains; 2 m coal seam with brown clay; 2 m sandstone, fine, weathering brown, with calcareous streaks; 19.6m sandstone, soft and white, with irregular clay laminae; 99 m basalt, massive, probably a sill; 1.4 m brown sandstone; 10.8m sandstone, soft white, with a thick discontinuous body of massive brown weathering medium sandstone probably a channel fill; The sill meets the lava in the west (as was noted by Nathorst). Each of the six intermediate sections measured is different (Smith et al. p. 205). At the northernmost mountain Mohnhogda (20 km to the north) two basaltic

;RA

lava flows, 17.4 and 44m respectively, cap the mountain with 10.3m sandstone between and 7.3 m in sandstone beneath. They are not separated by sandstone to the south at Dun6rfjellet. In each case the topmost lava forms a protective covering to the softer sandstones beneath and only a narrow ridge remains9 Nathorst recorded Cladophlebis sp. Taeniopteris or Anamozamites, Podozamites laneeolatus pichwaldi and Pinus sp. H~rfagrehaugen (sandstone and basalt) Mbr of western Kongsoya. The type section is at Tordenskjoldberget and is confused by several slipped masses, referred to as Belemnitkullarna (belemnite mounds) by Nathorst, with mixed origins. This member comprises 14m mainly of sandstone beneath a thinner basalt lava. Loose to unconsolidated sandstone, (medium to coarse) siltstone and shale make up the sedimentary part. Coal and carbonaceous beds are characteristic and two lava flows (generally in contact) cap the mountain. Compressed plant remains have well preserved cuticles. Petrified wood occurs, several trunks being up to 1 m long just beneath the basalt, and some fragments were found in the basalt shot through with siliceous veins. Such material, probably from here, was described by Gothan (1907) who commented that the excellent preservation could be attributed to the

EASTERN SVALBARD P L A T F O R M PASSEr

SJIZ~.-,RENFJELLET

TORDENSKJOLDBERGET

W

E

..

..

7-" v I basalt

-

Vv

"-,'1 -

v

basal1

I

100

.. Kong Karls Lend Fm

200 m SJcrgrenllellet M e m b e r

-

85

v

_ --__

x ? dolerite X X

Rotzlu,~ot _

blombor

Kono~o Fm

svom~qo Fm

?

/o

0

1

2

3

4

I

I

I

I

I

5 km

I

overriding lava. He identified the following species which included new taxa suggesting at first a Late Jurassic age but later (1910) changed to early Cretaceous: Phyllocladoxylon sp; Xenoxylon phyllocladoides Gothan; Cupressinoxylon cf. mcgeei Knowlton; Cedroxylon cedroides Gothan; Cedroxylon transiens n.sp; Protopiceoxylon exstinctum Gothan. From evidence in Kong Karls Land, a Valanginian or later age is deduced. By lithological analogy with Spitsbergen the age may be Barremian. Johansenberget (sandstone and basalt) Mbr of eastern Kongsoya. At the top of the hill are 30 m of sediment underlying 20 m of basalt. The sediments include Nathorst's bed 10. Sandstones with plant remains are conglomeratic in part. In conclusion, throughout the islands the basalts are better exposed than the sediments and generally at least two lava flows can be traced either in contact with each other or separated by sediment. Reconnaissance investigation of the Kong Karls Land Fm palynomorphs gave three significant results. (i) Rhaeto-Liassic spore and pollen types occur and suggest that erosion of the earlier strata contributed to the sediments. (ii) Lack of angiosperm pollen indicated an age earlier then Albian. (iii) The main flora is of long range species, not older than latest Jurassic, and entirely consistent with Early Cretaceous. All characteristics indicate a non-marine environment for the Kong Karls Land Formation. Kongsoya Fro. This unit is of typically marine facies dominated by shales rather than sandstones. It would thus appear to correspond stratigraphically to the Janusfjellet Subgroup of Spitsbergen. The particularly well-preserved Arcticoceras fauna in the lower part of the formation is of mid-Bathonian age (Rawson 1982). The early record of Arctocephalites arcticus (Newton) in Kong Karls Land was of Early Bathonian age (Pompeckj 1899; Arkell 1956) but has not been collected recently. These Bathonian faunas may be compared with the fuller East Greenland sequence (Callomon 1994). Dnn~rfjeUet (shale) Mbr, 6 3 + m (in Svenskoya). A shale unit, with distinctive upper and lower divisions, but the base is not seen. Upper division, 19m tough shale with bivalves Buchia, ammonites Amoeboceras (Amoebites) of early Kimmeridgian age and fish fragments probably including the new species Leptolepis nathorsti (Woodward 1900). Lower division, 42+ m (bottom not seen) is of weathered dark grey shales with small belemnites and ammonites preserved in pyrite: Cardioceras cf. cordatum (Late Oxfordian) and Arcticoceras and Cadoceras (Late Bathonian or initial Callovian). Facies are variable, even in the small outcrop on Svenskoya, and include northeast of Kiikenthalfjellet a unit 47 m with horizons of clay ironstone, similar to Janusfjellet, where fish fragments characterize the upper part and belemmites and pyritized ammonites the lower part. At Mohnhogda the member is represented by 20 m of dark shale. No macrofossils were recorded there but organic microplankton indicate a marine environment. The thickness was probably reduced here by preKtikenthalfjellet Member erosion. Tordenskjoldberget (limestone) Mbr, 30 m in southwestern Kongsoya. This is of limited extent known only from near the type locality 1.5kin east of Passet and was estimated by Bltithgen (1936, p. 59) to be of Early and Mid-Valanginian age. To the east it is rich in belemnites which weather

;RAI

Fig. 5.10. Correlation of the principal stratigraphic sections on Kongsoya (redrawn with permission of Cambridge University Press from Smith et al. 1976).

out of mounds formed by landslips. To the west it is overstepped by the Kong Karls Land Formation. One of the few occurrences of extrusive igneous rocks below the Kong Karls Land Formation is seen within this member as bright red weathering pumice including fragments of baked sediment. This Valanginian eruption is the earliest evidence of igneous activity in western Kongsoya. Upper division (15m) shales, siltstones with dark brown weathering ironstone nodules and a calcareous horizon, 4 m above the base with bivalves. Lower division (15 m) of white and light yellow loosely cemented calcareous sandstone consisting of inoceramid type fragments. Complete Buchia keyserlingi (Lahusen) are common together with abundant belemnite guards. The solitary coral ?Theococyathus nathorsti (Lindstr6m 1900) was recorded. Retziusfjellet (shale) Mbr, 7 5 + m in western Kongsoya. This member correlates with the upper division of the Dun~rfjellet Member of Svenskoya. At the type section it rests on the thin orange-weathering hardground at the top of the Passet Member. It consists of grey and black shales with occasional horizons of nodules weathering red or yellow. At Retziusfjellet in particular some concretions are large, some septarian, and many with ammonites, belemnites (with phragmocones) and bivalves in full relief. The youngest ammonite fauna consists of Amoeboceras (Amoebites) kitchini and Aulacostephanus (Xenostephanus), probably of Early Kimmeridgian mutabilis zone, and Amoeboceras with Rasenia probably cymadoce zone and flattened Amoeboceras (Hoplocardioceras). Mid- or Late Callovian ages are implied by Longaeviceras? and Quenstedtoceras s.1. (e.g. Eboraciceras) The oldest confirmed fauna is the Arcticoceras fauna dated as early ishmae zone (mid-Bathonian) by Rawson (1982). The Member is overstepped at Passet by the Kong Karls Land Formation. Passet (clay) Member 65+ m in western Kongsoya, is predominantly of clayey beds, generally unconsolidated and including occasional ironstone nodules and beds of sand or sandstone. It is cut out to the west by the Kong Karls Land Fm (Hgtrfagrehaugen Mbr) and is approximately equivalent to the lower divisions of the Dun~rfjellet Mbr of Svenskoya. It includes occasional ironstone nodules and beds of sand or sandstone and a fauna of small belemnites. Nathorst's estimate of this bed 4 was Mid- to Late Callovian. There is a Sinemurian-Toarcian foraminiferal date (Lofaldli & Nagy 1980); Doyle & Kelly (1988) gave an Aalenian (possibly Toarcian) Bajocian age based on belemnites alone. Eastern Kongsoya In the upper slopes of Johnsenberget clays, siltstones, yellow and green sandstones are exposed with belemnites and bivalves and a calcareous sandstone near the top. These belong to the upper part of the Kongsoya Fm. Nathorst's equivalent (Beds 8 & 9) would suggest an early to Middle Valanginian age for the bivalves. Nordaustpynten (shale) Mbr (?150-200 m), is a black shale also placed in the Kongsoya Fm. It occupies the lower slopes and the extreme eastern sea cliffs of Kongsoya where between two basalt layers, probably extrusive, is a horizon with flattened ammonites and bivalves ?Rasenia/Aulacostephanus with cardioceratids indicate an Early Kimmeridgian age. In the southeastern exposures bright red baked shales mark eruptions, probably volcanic.

86

CHAPTER 5

Wilhelmoya (Svenskoya) Fm. This formation comprises an upper continental sandstone division and the upper part of a lower shale division and occurs the length of Svenskoya, but only in western Kongsoya, being in each case the lowest formation above sea level. The sands are unconsolidated (without cemen0 and of high porosity, a facies not reported in Spitsbergen. Nevertheless there is some similarity in facies and position with the original De Geerdalen Fm, particularly its upper unit, Worsley's Wilhelmoya Fm. However, Worsley & Heintz (1977) acknowledged that the De Geerdalen Formation had been defined to include all rocks up to the "Lias conglomerate'. They reported a lower unit, the Kapp Koberg Member, which usefully extends the Kongsoya sequence downwards. They also recommended to drop the name Svenskoya Formation in favour of Wilbelmoya Formation (Worsley I973) accepted here. Mohnhogda (sandstone) Mbr, 197m in northern Svenskoya is thickest at Mohnhogda where the lowest 50m is largely obscured by loose talus from the sands above. It consists mainly of sandstone or loose sand coloured grey, yellow or brown with occasional interbeds of sandstone bearing fragments of fossil wood. Further south thin pebble horizons occur and at the far south a thin gravel conglomerate. Arnesodden (shale) Bed, 5 m to sea level. This Mack shale and siltstone occurs at the base of the steep sandstone slope and represents the lowest beds exposed in Svenskoya. Sjogrent-jellet(sandstone) Mbr, 130+ m possibly 235 m in western Kongsoya corresponds to the Mohnhogda Member in having poorly consolidated fine sandstone with stringers and interbeds of grey and brown clay, and thin coal seams. Beds of harder sandstone, some weathering orange, and pebbly horizons occur. Plant fragments, wood and lignite were noted at Passet where slump structures were seen in the sands. Kapp Koberg Mbr, 36 m in western Kongsoya. Whereas the above units were all described by Smith et aL (I976). This member was newly defined by Worsley & Heintz (1977) and extends the Kong Karls Land sequence downwards. It is a conspicuous in the cliffexposure near sea level, at the base of a cliff and may have been obscured by ice foot in 1969. The member is a shale, coarsening upwards to sandstones of which the lower 13 m consists of poorly consolidated mudstones with silty interbeds. The friable sandstones with cross-bedding indicate N NW to W directed flow, with similar orientation of the plant fragments. The lower 25 m of the whole section contains occasional vertebrate remains in sideritic beds or in small erosive washout structures. One sandy bed contained a large sideritic concretion with a nearly articulated plesiosaur skeleton. It was partially eroded in the cliff section. Parts of which were collected together with the palynomorphs so providing a marine assemblage. WBhehnmya Fm palynomorphs. The palynomorphs from upper and lower horizons in the higher sandstone units of the Svenskoya Formation were investigated by Smith (Smith et al. 1976) from samples from north and south Svenskoya. Preservation is good. The assemblages almost entirely without marine influence except for occasional microplanton but no dinoflagellates. All the taxa have Rhaeto-Liassic ranges. The assemblages from the upper part of the formation in each locality were similar and correlation was suggested tentatively with Orbells" (1973) two zones (based on sections in England, Sweden and Greenland). The lower samples collected near sea level, approximate to his Rhetopollis zone and the remaining preparations to his Heliosporites zone. With several qualifications enumerated by Smith this could indicate a Triassic-Jurassic boundary somewhere within these sandstone members. A late limit of Sinemurian was suggested and the earliest part is probably Rhaetian. This conclusion is consistent with palynological work by Bjaerke (1977), Bjaerke & Dypvik (1977), and Bjaerke & Manum (1977) and makes it almost certain that the Kapp Koberg Mbr is Rhaetian. Smith made comparisons with Hopen (Smith et ai. 1976), confirmed by Bjaerke & Manum (1977), that the lowest shale unit in Kong Kads Land and the overlying sandstone represent a marine followed by a non-marine sequence very similar to the sequences in Hopen and Wilhelmoya and could thus all be coeval. The age of the Arnesodden shale bed remains uncertain. It could be an extension of the Kapp Koberg Member, but it has not been investigated.

5.7

Barentsoya, E d g e o y a and T u s e n e y a n e

Edgeoya, t00 km from north to south, is the third largest island in the Svalbard archipelago after Spitsbergen and Nordaustlandet. It is nearly half covered by ice which tends to occupy the higher ground rather than concentrate in valley glaciers. Barentsoya at perhaps a quarter of the area is the fourth largest.

Pre-Quaternary strata are remarkably uniform throughout both islands on which Triassic outcrops exceed in area the combined Triassic outcrops of the rest of Svalbard. Exceptional Permian inliers give a base to the Triassic succession and the highest mountains in southern Edgeoya are capped by the youngest s t r a t a - probably Rhaetian, possibly Hettangian. Dolerite sills occur extensively and form the 'thousand islands' (Tusenoyane) scattered throughout an area (the size of Barentsoya) to the south o f Edgeoya. It is convenient to treat the two main islands together.

5.7.1

Earlier work

The southern coast of Edgeeya protected by the dangerous Tuseneyane was probably known from the early expeditions o f Barents from 1959 and shown on a map by Plancius in 1612. The name is for Thomas Edge an English whaler whose visit in 1616 may be the first recorded. Barentsoya was not known to be an island separate from Spitsbergen until the middle of the nineteenth century. It had been k n o w n as Barents Land. Fuller details of this early history entailing the (mainly British and Dutch whaling fleets are given in Place Names o f Svalbard (Norsk Polarinstitutt Skrifter N o 80, 1942). The first geological record is by Keilhau in 1827 and the second by Lamont in 1859 with fossils identified by Salter (Lamont 1860). From Nordenskirld's 1864 expedition material was shown to be Triassic (Lindstrrm 1865). The Russo-Swedish Arc of Meridian Expedition 1899-1901 was the first systematic survey of the western parts of the islands from which Wittenburg (1910) described Triassic faunas and Baeklund (1907) described and interpreted (1921) the dolerite intrusions. Arising from the same Swedish work was De Geer's contribution including these islands in his general account of Svalbard (1910). The Scottish Spitsbergen Syndicate was geologically active after the First World War in several parts of Svalbard in support o f mineral claims, giving rise to several useful publications. In the course of work in Storfjorden, Tyrrell (1933) described sections from the west coasts o f Barents~ya and Edgeoya. This interwar period saw the beginnings of Oxford and Cambridge expeditions including one to Edgeeya led by G. Watkins on which Falcon (1928, later Chief Geologist in British Petroleum) proposed a three-fold division of Triassic strata which has continued to this day. He noted the importance o f the lower unit (the oil shales group). Little was done in these islands geologically until the new stimulus of the search for hydrocarbons beginning about 1960 (e.g. Nagy 1965). At this time also there was renewed interest in describing lithic units in which to relate paleontological records so leading to new systematic schemes o f nomenclature. A distinct Soviet contribution in this episode was the description of the three Permian exposures beneath the Triassic strata, one quite easily seen on the north cast coast of Barentsoya and two minute inliers in the interior of Edgeoya (Klubov 1964, 1965a, b, c). The next significant geological exploration of the islands was in 1969 by two independent groups, one from the Norsk Polarinstitutt, Oslo, (Hood, Nagy & Winsnes 1971) and the other from Cambridge Svalbard Exploration (CSE) in cooperation with Norskefina (throughout eastern Svaibard). Both had the benefit of helicopter support from ice-strengthened ships. In each case research continued from that 1969 basis. Flood, Nagy & Winsnes (197I) published their first results on these islands and Hopen. Their paper included a map of the islands to a scale of 1: 500 000. Edwards (1976) noted growth faults in the Late Triassic unit seen from the air in cliffs at Kvalpynten. Much other Norsk Polarinstitutt work has been concerned with topographic survey and Quaternary studies. Two deep wells were drilled in Edgeoya which CSE investigated (Section 5.7.3 below) one interpretation of which has been published (Shvarts 1985).

EASTERN SVALBARD PLATFORM

No overlying unit remains in these islands. The base of the formation is taken at the first prominent sandstone (thicker than 1 cm) above the underlying shales of the Tschermakfjellet Formation. On this basis the boundary is transgressive and presumably correspondingly diachronous. The formation is at least 400 m in Edgeoya and 240 m in Barentsoya. It is of, generally flaggy, sandstones with subordinate siltstones, sandy and silty buff shales with rarer black and grey shales, thin coal seams ironstone and oolitic, micritic and shelly limestone beds. Flood et al. (1971) reported that the sand grains rarely exceed 0.5 mm with an average composition of quartz 40%, rock fragments 30%, cherts 15%, alkali feldspar 10%, other grains (including muscovite and plagioclase) 5%. They regarded euhedral quartz grains as suggesting derivation from the Precambrian quartz-porphyries of Nordaustlandet, but Lock et al. considered the crystal shapes as authigenic. Cement is generally of calcite, often sparry with carbonate mud. Organic remains include fossil plants and some bivalves (including oysters in some beds). Klubov (1965a) recorded a specimen of Nathorstites at the base of the formation at Negerpynten. Echinoderm fragments have also been reported. Falcon recorded a reptilian jaw bone with teeth in the same general locality. The sedimentological model (D.J.A. Piper in Lock et al. 1978) is of a delta complex supplied by rivers from the northeast entering a marine basin. This interpretation is based on seven lithofacies (i) Turbidites (0.01 to 1.Sm thick) with sole marks especially groove casts and Bouma C and BC sequences. (ii) Thick sandstones filling slide scars up to 30 m deep. The sliding units are mostly of turbidite facies. Channel structures and mudstone intraclasts are also observed. (iii) Shallow marine sequences occur as coarsening-upward cycles of silty shales followed by sandstones with bioturbation. The sandstones may be cross-bedded in sets up to 10m thick followed by massive sandstone (Edwards 1976b). They are sometimes capped by a coquina or oyster bed. Marine sequences are more abundant in the lower part of the formation and a shallowing marine or marine environment was suggested. (iv) Mouth bar sequences in the form of sandstones up to 3 m with largescale high angle cross-bedding. Load structures occur in the underlying thinner sandstones. These characters suggest prograding mouth bar facies. (v) Fluvial channel sequences with upward-fining sequences are cha~teristic of the upper part of the formation may be associated with (vi) Fluvial overbank facies of thick dark siltstones and mi'nor silty coals, mudstone intraclasts and plant fossils. (vii) Marginal marine facies of ironstones (some oolitic), sandy stromatolites, thin algal limestones and beds with high concentrations of bivalves,

The CSE work on the surface outcrops was published after an agreed interval (Lock e t al. 1978) in parallel with work on other islands: Wilhelmoya (Smith 1975), Hopen (Smith, Harland & Hughes 1975) and K o n g Karls Land (Smith e t al. 1976). Lock e t al. took previous work into account and made the basis for the present summary. However it could not have noticed the work of Pchelina (1977), who gave more biostratigraphic detail from molluscan faunas which was not in conflict with CSE conclusions. The Norsk Polarinstitutt map: 1:500 000, sheet 2G, Edgeoya (Winsnes 1981) accompanied by a commentary (Winsnes & Worsley 1981) follows almost exactly that in Flood e t al. (1971). The commentary remarks 'The lithostratigraphic units concern with those of Flood e t al. (1971) [see Fig. 5.11], and adopt neither the proposals of Lock e t al. (1978) for Barentsoya and Edgeoya nor those of Smith e t al. (1975) for Hopen are adopted here. It is noted, however, that a revised stratigraphic scheme for Triassic strata of the entire Svalbard will be proposed in the near future' (A. M o r k pers. comm.). This book attempts to assess and synthesize all points of view and so far as Triassic classification and nomenclature is concerned the matter is discussed in the Triassic chapter Section 18.1 and 18.3. The conclusions arrived at there are applied here without further discussion.

5.7.2

Stratal succession

Figure 5.11 shows the relation between the scheme adopted here (and justified in section 18.1.3) and earlier schemes. A generalized geological map of Barentoya and Edgeoya is shown in Fig. 5.12 showing the distribution of the principal formations. Kapp Toscana Gp De Geerdalen Fin (Buchan et al. 1965)= Negerfjellet Fm (Lock et al. 1978) >400m. This is the 'Sandstone Group' of Falcon (1928). It corresponds to the De Geerdalen Formation and perhaps the uppermost part of the Tschermakfjellet Formation of Flood et al. (1971) - units that were defined by Buchan et al. (1965) in Spitsbergen and approximately equivalent in these islands. Lock et al. (1978) based it on a measured type section at Negerfjellet in southwest Edgeoya (op. cit. p. 29) supported by five other sections extending to northwest Barentsoya.

Falcon 1928

Klubov 1965

Sandstone Group

"Sandstone formation" (Upper unit of T3)

Purple (Blue & Purple) shales group or series

"Passage Beds ! (lower formation" | two

Flood etal. 1971 Winsnes & Worsley 1981

s (.9

8 P-

units

"Argillite formation"

/ of ,A T3)

De Geerdalen Formation

v

Tschermakfjjellet Formation

Lock et aL 1978

o (.9

80~ ~2 o. Q. (~

Oil Shales group or series

T 1 and T 2

~) Sticky Keep Member

-~

(/)

(~

(Permian rocks not recognised)

"Selander suite"

~--~~) EE ~ $ eLL vo

Vardebukta Formation

Kapp Starostin

Formation

Mork et al. 1982

This work

Nege~ellet Formation

De Geerdalen Formation

De Geerdalen Formation

s (.9

Edgeoya Formation

Tschermakfjellet Formation

Tschermakfjellet Formation

~r

I

Botneheia Member

87

P3~ Oil shales I Member I ---~) ~ Barentsoya Formation

I

Blauknuten Beds ?

I I

.

.

.

Barentsoya Formation

.

.

Oil shales Member . . . .

I

I I

s

(.9

g

Barentsoya Formation o~ CO

Kapp Ziehen formation

Kapp Starostin Formation

Kapp Starostin Formation with Kapp Ziehen, Raddodalen and Veidebreen units (members?)

Fig. 5.11. Proposed nomenclature for local rock-units on Barentsoya and Edgeoya as used in this work, compared with previous authors' schemes.

.~ =~ (.9 __

88

CHAPTER 5 ironstones. But formal members were not proposed because the boundary is ill-defined (Lock et al. 1978). The lowest beds of the formation are generally characterised by abundant ironstones. But locally by grey shale. The variable thickness appears to result in part from facies variations within the unit and partly from the vagaries of the succeeding deltaic front. The formation is characterised by marine fossils- ammonites and bivalves with a bed rich in N a t h o r s t i t e s 20 to 30m above the base. This Nathorstites band forms a useful marker horizon. Silicified wood also occurs.

Sassendalen Gp Barentsoya Fm, c. 300 m (Lock et al. 1978). This formation, as defined above

Fig. 5.12. Geological map of Barentsoya (to the north) and Edgeoya, combining figs 4 and 5(B) of Lock et al. (1978). generally of a single species. Marine facies may coarsen upwards into dark siltstones or coals. These facies indicate shallow open marine, lagoonal, tidal flat swampy terrestrial environments. In addition, conspicuous rotational faults developed with sedimentation seen in the Negerpynten cliffs. The strata dip up to 20 ~ northwards as a result of the southward slipping rotation. They were noticed by De Geer (1919), Falcon (1928), CSE 1969 and described by Edwards (1976a, b). Abnormally high fluid pore pressure may have facilitated this faulting. It is not unexpected in the above complex that no satisfactory marker horizons have been identified in the formation. Tsehermakfjellet Fm (Buchan et al. 1965)= Edgeoya Fm, (Lock et al. 1978), 125m. This is the purple shale, or blue and purple shale unit of Falcon (1928) and the argillite plus Passage Beds of Klubov (1965a, b). In stratigraphic position it corresponds to the Tschermakfjellet Formation of Spitsbergen. The type section was taken at Veidemannen in southwest Edgeoya (Lock et al. 1928, p. 4). It is clearly distinguishable from the Negerfjellet sandstones above and the cliff forming bituminous shales of the Barentsoya Formation below. The type section is supported by six further measured sections, four in Edgeoya and two in Barentsoya. Thicknesses were plotted at 26 localities in the islands and range from 51 to c. 130 m. The formation is entirely missing at Mistakodden in northwest Barentsoya. The formation consists of shales with subsidiary fine siltstones becoming more abundant towards the top. There are thin red to purple-weathering clay-ironstone beds and thin argillaceous and arenaceous micritic limestones some with cone-in-cone structure. The lowest bed is of yellow-weathering calcareous silts and small nodules. The upper part of the Edgeoya Formation is, as Klubov reported, somewhat transitional to the succeeding deltaic facies and two divisions are thus discernible, the lower one being of shales and red weathering clay

and as followed by Mork et al. (1982), completely represents the Sassendalen Group in these islands, it not being practicable to map divisions within it, whereas the Group is defined by three distinct formations in Spitsbergen. It corresponds to the 'Oil Shales Group' of Falcon 1928, T I + T 2 of Klubov (1965a, b), and the Kongressfjellet and Vardebukta formations of Flood et al. (1971b) which were extended from the mainland of Spitsbergen but without detailed sections. The type section is a composite one near Kapp Ziehen in northeast Barentsoya where it rests directly on the Permian sandstones and limestones of the Tempelfjorden Group. This lower boundary at Kapp Ziehen, not well exposed, was described by Burov et al. (1965) as a pitted erosion surface. The boundaries at the two Permian inliers in Edgeoya are still less visible. The upper boundary is easily observed throughout the outcrops being marked by a sharp change from compact paper shales, often bituminous, to the overlying purple or grey shales with red-weathering concretions. The main and upper part of the formation crops out from northern Barentsoya to southern Edgeoya and was depicted in six representative measured sections (Lock et al. 1978). It is a unit of shales, often bituminous and papery towards the top and with subordinate beds of limestone, septarian nodules, calcareous siltstones and argillaceous sandstones. Septarian concretions often contain liquid bitumen, and phosphatic nodules occur lower down in the succession. At the top a distinctive bed of yellow-weathering argillaceous limestones or calcareous siltstones commonly occurs with ichthyosaur bones. This represents a widespread non-sequence and disconformity with the overlying strata. The cliff forming bituminous shales may be taken as an informal 'Oil Shale Member' in the upper part of the formation. It thins from 100m in the west to 50 m in the east. The lower part of the formation is of limited exposure near the Permian outcrops. Its relationship to the upper-part is not seen. It consists of grey shales and siltstones with a few prominent beds of yellow weathering carbonate-cemented siltstones and silty, clayey limestones. The formation is richly fossiliferous. Abundant ammonoids, often impressions, Daonella, ichthyosaur and plesiosaur bones, and fish remains are characteristic. The fauna is consistent with the euxinic interpretation of the bituminous shales forming in stagnant conditions on the sea bed. Tempelfjorden Gp. Permian strata are known from three localities: (i) at Kapp Ziehen in northeast Barentsoya reported by Burov et al. (1964); (ii) in central Edgeoya and (iii) in central south Edgeoya. Localities (ii)+ (iii) are tiny inliers (each less than 1 km 2) discovered by an Amoseas exploration party in 1963 (King 1964) and mentioned in the synthesis of Cutbill & Challinor (1965) who implied that all three exposures would correlate with the Kapp Starostin Formation of Spitsbergen. Flood et al. (1971) reported Klubov's discovery of Kapp Starostin Formation but no data were provided. Lock et al. (1978) reported on some fieldwork in 1969 at the three localities referring to all the rocks informally as Kapp Ziehen formation, but except for a general similarity with Kapp Starostin strata these occurrences could not be correlated within the two islands. The 1:500 000 geological map and text 2G (Winsnes & Worsley 1981) refers to all three localities as Kapp Starostin Formation. Therefore although correlation between Spitsbergen and these islands is not so good as with the more distant Miseryfjellet Formation of Bjornoya we adopt this nomenclature. Because of the distinct nature of the three occurrences and the convenience to label them for discussion it is proposed here to name them informally as follows: (i) The Kapp Ziehen occurrence to be the Kapp Ziehen member for that outcrop and not for (ii) and (iii) below. (ii) The central Edgeoya occurrence to be the Raddedalen member from the name of the well near that locality and which penetrated the Tempelfjorden Group.

EASTERN SVALBARD PLATFORM (iii) The Central South Edgeoya rocks to be the Veidebreen member from the neighbouring glacier. Kapp Starostin Fm (i) Kapp Ziehen member. The largest outcrop, extending for about 10kin along the northeast coast of Barentsoya described by Klubov (1965c). It is poorly exposed with only intermittent beds recorded dipping gently SSE. The outcrop suggests a thickness of at least 250 m but only the top 28 m are exposed as cherty limestones, dense, dark grey to black, in places transitional organogenic cherty rock. 60-70 m are covered. 1 m light grey shelly limestone with 10 brachiopod species. 10 m covered; 3.5m yellow organogenic cherty ferruginous rock (2 brachiopod species recorded); 10-15 m covered; 1.5 m light cherty, organogenic limestone. (7 species recorded); 10-15 m covered; 1.5 m light grey cherty, organogenic limestone (7 species recorded); 20 m covered; 1 m light grey shelly limestone (11 species recorded) 20 to 30 m covered; 5 m cherty limestone, dense dark grey with light calcite veining, echinoid spines and sponge spicules (10 species recorded); 100 m covered; 0.5 m Calcareous sandstone, green/grey, medium grained, thin-bedded, with glauconite and sponge spicules (2 species); Lower beds obsured. (ii) Raddedalen member. In central Edgeoya is a small outcrop with blocks of richly fossiliferous Permian strata but hardly exposed in situ. In the float the relationships with the overlying rocks cannot be seen. Its position is shown on the map, but it is not easy to locate on the ground. It occurs at the northern end of the pass between Storskavlen and Edgeoyjukelen. About 15 species of brachiopods, pectinid bivalves and bryozoans were collected (Lock et al. 1978). The unit is so named here because it was later the site of the well 'Raddedalen-l' drilled by the Companie Frangaise du Petrole (Total, CFP). The only previously published record was by Schwarts (1985) who, from mud samples exchanged, recorded 202m of Tempelfjorden Group above upper Gipsdalen Group etc. (see below). (iii) Veidebreen member. In Central South Edgeoya is a small outcrop in a complex exposure amongst meltstreams just north of the terminal moraine of Veidebreen. This is about 7 km NNE of the northernmost coastline of Tjuvefjorden. This exposure is of light grey chert with sponge spicules and bryozoa, but no brachiopods were collected. Fossil species were not easily identified. Palynological investigation yielded only one long ranging acritarch genus Micrhystridium.

5.7.3

Sub-surface stratigraphy

Two deep wells were drilled in Edgeoya. One in southwest Edgeoya by Norske Fina: Plurdalen-1, the second already mentioned was: Raddedalen-1 drilled by Compagnie Franqaise du Petrole (CFP). See also Section 5.9.

Raddedalen-1, 22~ 77~ The already published record (Shvarts 1985) concerns Raddedalen-1. The mud samples from this well were obtained from C F P in exchange for material from the Soviet well Grumantskaya-1. It was drilled to a depth below surface of 2823 m. The Cambridge samples were obtained through Norske Fina by exchange for Plurdalen-1 material. Below the 202m of Tempelfjorden Group, Shwarts recorded 205 m of Upper Gipsdalen Group and a Moscovian-Bashkirian boundary just below a depth of 407 m and down a further 306 m through lower Gipsdalen Group rock. Then 161 m of Culm was reported down to an unconformity at 874m. Of the remaining 1949m the upper 945m was interpreted as Early Silurian or Ordovician and the lower 1004m as Ordovician. Independently, and recently released information (courtesy Dragon Oil, was reported to Norske Fina in 1974 and 1975 on material by Cambridge Svalbard Exploration (CSE). The CSE work was primarily a palynological investigation by J. F. Laing,

89

advised by N. F. Hughes and the samples were cuttings etc. The conclusions were that below the more easily identified Permian and Pennsylvanian strata was a succession of about 2000 m of Early Carboniferous (Mississippian) and possibly late Devonian age. The Devonian palynomorphs all had ranges well into Carboniferous time if not younger. The two investigations are plotted side by side in Fig. 5.13. They were of course entirely independent, CSE results transmitted to Fina with little information other than depth in well from CFP. Obviously the C F P conclusions would be more useful. Shvarts with apparently more information on the well from C F P quoted 'foreign geologists' N. Couleau, I. Per6, A. Fedyayesky and D. Somm~ as giving the age of the lowest strata as Silurian?-Devonian. The critical evidence for Ordovician age is the conodont Drepanodus, which, if properly located in the well and properly identified and not a conglomerate clast, might well be conclusive. However, the general account of Shvarts would make this a quite remarkable result for Svalbard geology. He was able to report that the strata were a conformable sequence with dips ranging from 0 to 3 ~ and neither indicating tectonic nor magmatic activity. He suggested that Svalbard east of the Billefjorden Fault Zone was a stable platform escaping Caledonian tectonism. Apart from this conundrum the Russian report gives too much petrographic detail to recount here and generally not related to identified sample depths. The conclusions preferred here are put into context at the end of this Chapter (Section 5.9). Plurdalen-1, 21~ 77~ in southwest Edgeoya, just west of the snout Philippbreen, was drilled by Norske Fina. Cambridge Svalbard Exploration (CSE, mainly C. Croxton) reported palynologically on cuttings and selected cores which it is now possible to publish, courtesy Dragon Oil. The data here merely summarize results from six progress reports in 1973. The actual drilling occasioned widespread comment because of the conspicuous floods of red sediment emanating from the well. Because of this the first CSE study was to identify all red beds in Svalbard from the CSE collection. A summary of the results is plotted in Fig. 5.14. The whole-rock R b - S r determinations by Pringle were invited because the lithology of the red sediments appeared to be similar to the Vendian Nyborg Formation in Finnmarken from which he had obtained a result (1973). As we now know the Nyborg value (668 4-23 Ma) was significantly older than is currently thought likely (c. 600 Ma) and probably because of inherited clay minerals. On this basis the value of 410 M a (Early Devonian) could similarly be too high which could bring it to late Devonian or Early Carboniferous. Samples determined from different depths yielded no significant age differences.

5.7.4

Biostratigraphy[age estimates

?Jurassic strata. The possibility has been considered that the highest strata in the hill tops above Kvalpynten in south west Edgeoya may be earliest Jurassic, but no positive evidence has been forthcoming.

Triassic strata. Barentsoya and Edgeoya have provided rich collections of fossils (Fig. 5.15; from Lock et al. 1978, table 2). In comparison with an earlier similar plot, Flood et al. (1971b) did not emphasise the potential mid-Ladinian nonsequence separating the Barentsoya Formation from the Edgeoya Formation. No positive evidence for Rhaetian strata has been identified and the oldest strata, of which exposures are few, yielded Late (but not yet early) Griesbachian fossils. The recorded fossils, (ammonoids, stage by stage) were discussed by Lock et al. (1978, pp. 36-50).

Permian strata. Of the total of about 27 forms recorded from the Kapp Ziehen rocks by Klubov, most are brachiopods and there

90

CHAPTER 5

EDGEOYA

RADDEDALEN-1

Shvarts 1985 based on samples at 4, 8 and 10 m intervals Biostratigraphic age

W e l l d r i l l e d b y C o m p a g n i e Fran(~aise du P e t r o l e ( T O T A L ) Cambridge Svalbard Exploration (CSE) based on 56 evenly distributed samples or chippings in 4 reports from 1974-1975

Well depth (m) Lithic description

Lithic divisions based partly on recovered well log

Palynology by A.F. Dibner algae by G.P. Sosipatrova and M.F. Solov'eva Conodonts by N,N. Sobolevy 0

Late Permian 202 m

--100--

III

Palynological age, assessment by J.F. Laing advised by N.F. Hughes

Kapp Starostin Fm

Grey mottled chert with spicules

- - Sea level

b

202---200-Early Permian 205 m

-500-Middle Carboniferous 306 m

NO RESULTS

Gipshuken Fm

Approx. Wolfcampian EARLY PERMIAN

--300-- 407----400--

CSE corerlation optirnised by W.B.Harland, J.L. Cutbill and D.J. Gobbett, with unit names updated

NO RESULTS

White, light, medium and dark grey crystalline limestone II with shelly fossils, crnoids, corals, bryozoans and forams

Tyrellt]ellet Mbr Cadellt]ellet Mbr

Wordie Kammen Fm !

BASAL PERMIAN

~-6oo--

NO RESULTS

Minkinflellet Fm Ebbadalen Fm

.

.

.

.

.

Early Carboniferous 161 m

713_ ~ - - - 7 0 0 - ~

NO RESULTS

:T" : i

i: :

~800--

enlc imestones, algae, 674- ~_ 9 0 0 - / )otis, ostracods, echinoderms brachiopods, osl and foram fragments --1000Coral at 1049 m Nuia sibidca at 1054 m - 1092- ~_ 1100 - -

NAMURIAN (=EARLY BASHKIRIAN AND SERPUKHOVIAN)

(Hultberget Fm)

--1200

Early Silurian and Ordovician 945 m

Zoophytogenic limestone with scaps of algae and Giztare#a and fragments of brachiopods, crinoids, ostracods and conodonts

~ 1300-

/

-- 1400---1500--

Id White and light grey crystalline limestone with many beds of coral, pale green often pyritic fine sandstone, red fine sandstone and medium grey mediumgrained sandstone

(Mumien Fm) i

PROBABLY VISe:AN

--1600 -1649M~rophylithiclirnestone with brachiopods, crinoids andcale~rus

--1700

1819,--1800-Zoophytogenic limestone in uniform units with fine-grained limestone with numerous remains of algae in lumps and clots and fragments of brachiopods, crinoids, ostracods, and sponge spicules.

- - 1900 --2000 --2100---2200--

Ordovician 1004 m (on basis of Drepanodus)

Biogenic formations are evenly distributed as calcitic, often dolomitized cracks in limestones with black organic matter. The algae Nuia sibirica and the conodont Drepanodus was recorded

Ir Similar to Id, but mrdium grey mediumgrained sandstone is a more important constituent

H6rbyebreen Fm

--2300---2400 --2500--

Ib Similartolc butgrey sandstone of minor importance

--2600---2700--

Base of well 2823

VISE~AN OR TOURNAISIAN

--2800--

VISI~AN TO LATE DEVONIAN

la Similar to Ib but with appearance of dark grey fine sandstone as a major lithology

Fig. 5.13. Interpretations of Raddedalen-1 well (Edgeoya) by Shvarts (1985) and CSE, first published here, based on reports by J. F. Laing for Norske Fina, courtesy of Dragon Oil plc.

EASTERN SVALBARD PLATFORM

PLURDALEN-1

EDGEOYA

Well drilled by Norske Fina

Epoch

91

Stage

Zone

Well depth (m)

Equivalent Spitsbergen units ( 9 core sample)

_3

Approximate age

Norian Al~v~rrT --

-- 0 1

Barents~ya Fm (Sassendalen Gp)

Early Tdassic

Kapp Starostin Fm

Late Permian

I 3CSilicified

2 Camian 1

2 Asselian

Dolostone 538 Brucebyen Beds Wordie and . . . . . . . . 7 limestnne 555 , i Kamen i - - 602,5 - - 600 -- Cadellfjellet Mbr / Fm Oolitic and bioclastic 3A limestone - 7 0 0 . . . . . . . . . _ __Minkin_fje/letFro_ i --760.5 Quartzmc - 800 - sandston~ - 811 9

J

1

Orenburgian Gzelian

3

Moscovian

Anisian

"Early Carboniferous"

1

,~

--839-

Spathian

Slratigraphic break 9

-

Red beds almost entirely barren

-1100-

~_ I-

Z

Smithian

,~,

~

Dienedan

-1200Red beds

-1400-

_1600_ ~-1586 9 --1640- 9 1645 -1700-

Ii

i Ic. 410 al

Dark purple and red brick siltstones

8

Green beds

"1940 9 -2000spores found ~ No ? Pre-Devonian

-2200 - -2180 9

- 2300 -2344 9 "~Ann

Fig. 5.14. Interpretation of Plurdalen-1 well (Edgeoya), by CSE, first published here, based on reports for Norske Fina by C. A. Croxton, I. Pringle, J. L. Cutbill, D. J. Gobbett & A. B. Reynolds, courtesy of Dragon Oil plc. seems little chance that the faunas recorded would enable independently dating the seven fossiliferous beds so the fauna must be taken as a whole. A CSE collection of bivalves brachiopods and bryozoans from the Radeddalen outcrop was identified by D. J. Gobbett (who had monographed Svalbard Carboniferous and Permian brachiopods, 1963) and 15 brachiopod forms were listed (Lock et al. 1978, p. 18). Of these only four are named in common and another four might be the same with different names. A Ufimian age was in the end favoured (Lock et al., p. 16).

5.7.5

Madeami

wO .1-.LL

,,] I--

Possible

sequence I I[

Daonella trami, Panapopanoceras vemeuili, Ptychites trechlaeformis

Subaspedum Chischa

Gymnotoceras ?laqueatum

Deleeni Varium

? Hollandites Koptoceras

Caurus

Keyserlingffes subrobustus, Posidonia aranea, Svalbardiceras cf. spitzbergense

Subrebustus

"Pseudomonotis" occidentalis, Xenoceltites Arctopdonites nodosus

Tardus Romundefi Sverdrupi

Euflemingites, Posidonia mimer "Pseudomonotis" cf. multiforrnis

Candidus Strioatus Commune Boreale Concavum

Ophiceras (?) sp Claraia stachei

NOnL I I ?

Bivalves, bryozoans and brachiopods: more KAPPTOSCANA than 40 forms recorded by Klubov (1965) and rKappZiehenMbr) 17 brachiopods by Lock et al. (1978)

Fig. 5.15. Edgeoya and Barentsoya Triassic biostratigxaphy, after Flood, Nagy & Winsnes (1991) and Lock et al. (1978).

-1900 -

-2100 -

Guadelupian Kungurian

Rb-Sr 9 age of red beds

- 1 8 0 0 - ~1810 9

7

Halobia zitteli Nathorsites mcconnefli, N. tenuis, N. gibbous, Precladiscites cf. martini

Lopingian

LATE =ERMIAN

-1500-

Green siltstone and red brick argillite

Griesbachian

Unit 5 ? Bashkidan to Late Silurian spores

-1300-

,,'dz ,,?o

Nanseni

Pilaticus

r -1000

~L~

_i

Sirenites sp., Nathorsites gibbous

Meginae Poseidon

Ladinian

3B

- 900 - -

Macrolobatus Welled

Obesum

Tyrellt]ellet Mbr

m~ w~ O0

Dawsoni Kerri

Su~eflandi

- 400 -484.5 - _ 500 --

Meleagdnella antiqua, Lingula cK polads, Pentacrinus (?) sp., Estheria cf. minuta

Dilleri

Eady Permian

Gipshuken Fm 3 Carbonate section --

Palynomorphs and Pterophyllum sp., Macrotaeniopteris sp., Taeniopteris sp., Podozamites sp., Tod/tes sp.,

Magnus 1

- 300 --

Suess Columbianus Rutheffo~i

2

"Shaly Lower Triassic." --100 ---128.5- 2 0 0 --

Formations

Marshi

Rhaetian Descriptive units

Key Fossils (after Flood et al. 1971 & Lock et al. 1978)

Structure and igneous bodies

The large area of the two islands, a distance of > 150 km N-S and 75 km E - W is occupied almost entirely by Triassic outcrops representing a maximum thickness of between 800 and 900 m with a

typical relief of between 400 and 450 m. The strata thus seem to be flat lying. However interest is attached to the detailed structure from the point of view of hydrocarbon exploration. Figure 5.16 shows contours at the top of the Barentsoya Formation from data obtained in 1969 (Lock et al. 1978). There is insufficient control to have confidence in the exact structure but it is clear that there are significant minor basins and swells with a closure of 50-100m and two of the Edgeoya swells were drilled. Sills in the main islands and the basic bodies that constitute the 'thousand islands' (Tusenoyane) were described in considerable petrographic detail by Backlund (1907 et seq.). The distribution of the typical sills in Svalbard was summarized by Tyrrell & Sandford (1933). It is noteworthy that in the two main islands and especially in their western coastal areas. This seems to be part of a zone running the length of Storfjorden and Hinlopenstretet. Their age (?latest Jurassic through to Barremian) is discussed in Chapter 19. They affect the structure locally as might be expected.

5.8

Hopen

Hopen (70~ I'N, 25~ is a straight narrow island trending between N N E - S S W and NE-SW, about 35 km long and 0.5-2.5 km wide, with a mountain plateau around 300m rising to 370 m at Iversenfjellet in the south. The plateau slopes gently to the SE and is bounded by cliffs that fall directly into the sea or to a low raised beach. Shallow waters (largely uncharted shoals) offshore for more than 1 km prevent access by all but small boats and then only at a few favourable landings. At one of these is the radio station on the east coast about 8 km north of Kapp Thor at the southern tip of the island below Iversenfjellet. The plateau is punctuated by about five saddles each corresponding to the narrow necks in the islands plan. These are probably the remains of valleys in a much larger island.

92

CHAPTER 5

Fig. 5.16. Generalized structural map of Barentsoya (to the north) and Edgeoya, with structure contours in metres for the top of the Barentsoya Formation, combining figs 4 and 5(B) of Lock et al. (1978).

The regular elongate shape of the island implies a N E - S W structural control confirmed by lines of offshore submerged rocks; but there is no apparent dip across the island - the sloping plateaux being the result of differential erosion between east and west coasts of the island with stronger seas and currents on the west. Transverse structures cut across the island. Some are anticlinal and correspond with the saddles, some are the result of faulting which let down higher strata in the north; but the dips in the step-faulted blocks are southwesterly. They strike W N W - E S E . The net effect is to displace the marker horizon at the top of the lower formation from 325 m asl in the southwest systematically to 150-160 m at Lyngefjellet and up to 180 m at the northeast tip.

5.8.1

Earlier work

This account is as summarized by Smith, Harland & Hughes (1975) who reviewed earlier researches and gave the most complete account of Hopen geology to date based on 1969 and later fieldwork (Fig. 5.17). The history of geological exploration is brief because of the remoteness and difficulty of landing on the island protected by inshore shallows. Access for drilling in 1972 and 1973 was by means of hovercraft from a ship anchored some distance off-shore. The rocks were taken to be Mesozoic because the dominant sandstone lithology favoured correlation with the Spitsbergen

Fig. 5.17. Geological map of Hopen and a longitudinal section along the island, redrawn with permission of Cambridge University Press from figs 2 and 3 in Smith et al. (1975).

EASTERN SVALBARD PLATFORM succession, but opinion as to their age wavered between Triassic and Cretaceous from the lack of decisive diagnostic fossils afforded by the cursory visits. Nathorst's (1884) study of Paleozoic Arctic floras maps Hopen as Triassic but his 1910 m o n o g r a p h leaves it blank. He failed to land on Hopen in 1889. He later suggested a Jurassic age on the basis of plant fossils collected by the Prince of Monaco's expedition in 1898. Hoeg (1926), from the presence of coal, argued a Cretaceous age. Norwegian expeditions in 1924 & 1926 (Iversen 1926) resulted in some geological observations as well as a topographic map, e.g. Werenski61d (1926) on general geology, Hoel (1925) on fossil plants and Bodylewski (1926). F r o m these Hoeg proposed a late Triassic and the others an early Cretaceous age. Another Norwegian expedition to Franz Josef Land (Horn 1932) collected pieces of coal in passing and a Cretaceous age was suggested. These data were perhaps the only basis for later published estimates, e.g. Frebold (1935, 1951) and Orvin 1940 assumed Cretaceous ages in their review syntheses of the Barents shelf and Spitsbergen respectively. However, Selling (1944, 1945 and 1951) from three studies of Hopen concluded only Late Triassic to Early Cretaceous possible ages. Buchan et al. (1965), with no further evidence, suggested a Triassic correlation, and a Swedish-Finnish expedition in 1965 from observation at sea also suggested a Triassic age. These questions were settled from field work in 1969. Flood, Nagy & Winsnes (1971) who found not only that the lithologies matched those of the De Geerdalen Formation of Barentsoya and Edgeoya, but confirmed this correlation by collecting Pteridophyllum common to both. They also reported Halobia zitteli, a gryphaea, and one ammonoid, probably Arctosirenites. These ruled out a Cretaceous age but were not so specific as to a likely Late Triassic age. However the published report is brief with no section. Russian work in 1966 and 1971 (Pchelina 1972) resulted in a composite stratigraphic succession for the southern part of the island divided into Carnian and Norian stages partly on lithological grounds but with reference to fossil plants, bivalves and phyllopods. She suggested that the north of the island might preserve Jurassic strata. Similarly Worsley (1973) suggested that his proposed Wilhelmoya Formation might occupy the hill tops in the north where there was some evidence of down faulting. Exploratory wells were drilled by Norske Fina and associates in 1971 and 1973. These followed a preliminary study of samples by W B H in 1967 and field work in 1969 by a CSE party. The resulting paper (Smith, Harland & Hughes 1975) summarized available knowledge and reported permissible results from these investigations.Their conclusions are summarized below.

weathering bright red-brown to purplish which tend to follow the coarser horizons. At the bottom is a horizon of brown bioturbated siltstone. Rare ammonoids and abundant bivalves are found in the clay ironstone beds. The member is marine throughout with ammonoids, bivalves, ichthyosaurs, acritarchs and dinoflagellates. The scarcity of ammonoids and the good spore and pollen content suggest a near shore environment. Worsley suggested an Early Jurassic age but the palynological evidence makes a Rhaetian age more likely. Iversenfjeilet (= De Geerdalen) Formation, 325 m down to sea level at type section. This unit forms the greater part, and always the lower part, of Hopen. It consists of alternating sandstones, siltstones and shales in cyclothems of metres or decimetres. Shales or siltstones grade upwards into fine-, medium- or coarse-grained sandstones. The uppermost part is of calcareous, yellow-weathering sandstones with bivalves. The prominent ledge at the top may be Worsley's Basal Member. Lower down, siltstone and shale are the dominant lithologies, nodular ironstones, weathering red-brown are common at the base of the shale beds. Associated shales may be green or red. Siltstones are often bioturbated. The lower 100 150m in the south are often coarse-grained with large channel structures tens of metres across with cross bedding. The sandstones are often calcareous with beds of dolomitic mudstone. The age of the Iversenfjellet unit is probably latest Carnian to Norian and possibly earliest Rhaetian. Stratigraphic section at northeast Lyngefjellet from 290 m down to sea level from Smith et al. (1975).

Wilheimoya Fm Lyngefjellet (sandstone) mbr, 80+ m top of exposure; 15 m medium-bedded white sandstone with dark silty shale interbeds 35m massive quartz sandstones weathering white, thin bedded in part, occasionally pebbly; cross-bedded and ripple marked. 29 m Interbedded fine to medium sandstone and grey siltstone

Flatsalen (shale) mbr, 55 m; 55 m grey silty shales with red-weathering nodular ironstones especially near base. Three prominent beds of interbedded fine sandstone and siltstone. Bioturbated brown-weathering siltstone at base; 1 m prominent bed of yellow-weathering calc siltstone to fine sandstone with thin layers of coarse sand near top.

Iversenfjellet Fm 155 m; 95 m alternating fine to medium sandstone, silty shale and clay ironstone. about 13 cycles in this interval. Sandstones have ripple marks and small scale cross-bedding. Sandstone and siltstone often finely interlaminated. Shaly beds generally thicker (3-4 m) than sandstones (2 m); 60 m alternating sandstones and siltstones; sandstones medium-grained, thin to thick bedded, relatively little shale or siltstone.

5.8.3 5.8.2

Succession from outcrop

F r o m sections measured and collected from north to south three stratigraphic formations were proposed. However, Worsley (1973) proposed the Wilhelmoya Formation which has priority and to which he related the two upper units on lithological grounds. Smith et al. (1975) units are therefore taken as members of the Wilhelmoya Formation.

Wilhelmoya Formation Lyngefjellet (sandstone) Member, 80 m to top of hill is limited to Lyngefjellet and north in the hill tops. It is a white-weathering medium to coarse-grained sandstone mostly of quartz with occasional pebbles, cross bedding and ripple structures in the middle. Carbonized plant fragments are abundant and are often current oriented. The facies suggest fluvial deposition. The age of the member was estimated biostratigraphically as latest Triassic to earliest Jurassic (Rhaetian to Hettangian). It correlates with the Transitional and Tumlingodden Members of the type section of the Wilhelmoya Formation (Worsley 1973). Flatsalen (shale) Member, 55 m. The appearance is similar to the 'Aucella Shales' of the Janusfjellet Formation of Spitsbergen. It crops out as a less resistant unit between the sandstones above and below. Its main outcrop is in the north but three other outcrops cap the hills including Iversenfjellet. The dominant lithology is dark grey silty shale with prominent siltstone and fine sandstone horizons. The shales have beds of nodular clay-ironstone

93

Subsurface succession

The two wells, Hopen-1 and Hopen-2, drilled by Norsk Fina 19711973, were investigated by Cambridge Svalbard Exploration and summarized in Fig. 5.18. Hopen-1, 25~ 76~ near the southern tip of the island was drilled at near sea level to a depth of 908m and penetrated Norian into Anisian strata as estimated palynologically by M. G. Mortimer. Hopen-2, 25~ 76~ was sited on a hill top at the north of the island higher in the succession. J.F. Laing reported on the Triassic palynology. The Kapp Starostin Formation was met at about 1360m and drilling continued to c. 2870 still probably in lower Gipsdalen Group strata. There was little difficulty in correlating the strata with the Spitsbergen succession. Correlation between the two wells and those on Edgeoya as discussed in the Section 5.9.

5.9

Correlation of four exploratory wells: Edgeoya and Hopen

The four exploratory wells noted above (Sections 5.7.3 & 5.8.3) were drilled in the early 1970s namely: Plurdalen-1 and Raddedalen-1 in Edgeoya and Hopen-1 and Hopen-2. Cores and cuttings were made

94

CHAPTER 5

available to Cambridge Svalbard Exploration by Norsk Fina for independent opinions on the ages of the samples. The materials are now part of the Svalbard collection of the University of Cambridge by courtesy of Dragon Oil plc. The 25 biostratigraphic progress reports remained confidential until recently. In due course it would

be sensible to publish the mainly palynological results, and better still to combine all investigations in a comprehensive assessment. Only the broad conclusions of the Cambridge investigations directed by W.B.H. are reported here. The only other known publication was by Shvarts (1985) on Raddedalen-1 drilled by CFP. Some of this

EASTERN SVALBARD PLATFORM

95 Correlation with surface geology of Hopen

HOPEN-2 Approximate correlation with

-

BiUefjorden Trough RADDEDALEN-1

Early Triassic

Tatadan, Kazanian& Kungurian Artinskian Sakmadan& Asselian Kasimovian& Gzelian

- Mcmr Bashkilian

Namurian

•LUO

..........

....

Kapp Starostin Fm Gipshuken Fm

~Q(.

:111:

Svenbreen Fm

2

?__~,~

Lynge~ellet Sandstone Fm Flatsalen Shale Fm

1

i

I

$4.=a

HOPEN-1

: - - ~ ?9- ~ .~. . . . . . . . . . . . . . . I~' 3C

~

3b

, ~

3a

~

Iversenfjellet Fm

i a. o

Rhaetian

'< Norian and Camian

o VI-~ I I /

H

.....

II

.--9--

Cadelff]elletMbr Min~t Mbr~ Ebbadalen Fm

PLURDALEN-1 --lz

?--

Ladinian

t .9"

I

Anisian an( Scythian

Id

IV

Late Permian

Ill

Ic

Ib la

Fig. 5.19. Suggested correlation of the Edgeoya wells (Raddedalen-1 and Plurdalen-1) and Hopen-1 and Hopen-2 wells, based on CSE reports to Norske Fina and especially the final report by J. F. Laing, courtesy of Dragon Oil plc. material was exchanged by Norsk Fina and was added to the Cambridge investigation. The material Shvarts investigated was obtained by exchange for a Russian well, Grumantskaya-1. The preliminary conclusions are reported above: two Edgeoya wells in Section 5.7.3 and two Hopen wells in Section 5.8.2. An attempted correlation is shown in Fig. 5.19. The major problem was the age of the relatively barren red beds low in the Edgeoya wells. It was unexpected that the two Edgeoya wells should appear to be so different; still more unexpected that the two

reports on Raddedalen-1 should differ so much. There is probably a significant geological difference between the two Edgeoya wells suggesting separation by a minor fault. Both Edgeoya successions, according to the CSE interpretation, fit the idea of Svalbardian tectonics, possibly strike slip faulting accompanied by transtension with local subsidence in the typical Billefjorden continental environment. Triassic and possibly late Paleozoic strata appear to thicken systematically towards the southeast.

Chapter 6 Northern Nordaustlandet (and associated Islands Storoya, Kvitoya) W. B R I A N

HARLAND

6.1 6.2 6.2.1 6.2.2 6.2.3 6.2.4 6.3 6.3.1 6.3.2 6.3.3

Early work, 96 Stratal succession, 96

6.4.1 Laponiahalvoya granites, 105 6.4.2 The Rijpfjorden, Rijpdalen and Duvefjorden granites, 106

Hinlopenstretet Supergroup, 99 Murchison Bay Supergroup, 100 Kapp Hansteen Group, 103 Brennevinsfjorden Group, 103

6.5

Subjacent metamorphic complex, 104

6.6 6.7

6.4

Late tectonic plutons, 105

Evolution of ideas, 104 Migmatic and magmatic components, 104 Supracrustal inclusions, 105

Nordaustlandet is the second largest island in the Svalbard archipelago. It has been generally inaccessible by ship because of polar pack ice except for the west coast, or in exceptional summers. Exploration has therefore been limited. The major part of the interior is covered by two large ice caps: Vestfonna and (the large) Austfonna which forms all of the southern coastline in the eastern part of the island. Pre-Devonian, mostly Precambrian outcrops of solid rock extend along the northern and northwestern seaboard. Wahlenbergfjorden divides the west coast with post-Devonian rocks cropping out to the south of it. These have already been referred to in Chapter 5 so that the main object in this chapter is to outline what is known of the older rocks. Because of the ice caps covering the major part of the island, exposures, especially in the north and east, are often isolated on promontories along the highly indented coastline (Fig. 6.1).

6.1

Early work

After the early visit by Parry in 1828 research was largely by Swedish geologists with A.E. Nordenski61d's sledge journeys in 1861, 1866, 1869 and 1873. A Swedish initiative led to the Russo-Swedish Arc of Meridian Survey along both sides of Hinlopenstretet. During the period 1899 to 1902 (De Geer 1923; Nathorst 1910) and later the SwedishNorwegian expedition based at Sveanor in Murchisonfjorden (Kulling 1932) resulted in a thorough study of the Hecla Hock rocks (Kulling 1934). Alongside this were a series ofmultidisciplinary expeditions from Oxford University in 1924, 1935-36 and 1951. Sandford accompanied the 1924 expedition (1926) and since then he interpreted the many careful observations made by non-geologists aided latterly by the use of oblique air-photographs (1950, 1954, 1956, 1963). From their extensive surveys these expeditions for long provided the most reliable maps of Nordaustlandet (e.g. Glen 1937). The above work had depended on ship and sledge; then after sundry visits in 1965 the Norsk Polarinstitutt surveyed the large area of older rocks with helicopter transport. The resulting accounts are the principal sources for this chapter (Flood et al. 1969; Hjelle 1966, 1978a, b; Hjelle, Ohta & Winsnes 1978; Ohta 1978, 1982a, 1985). However, later isotopic studies have further elucidated the tectonostratigraphic history (e.g. Gee et al. 1995) and consolidated the evidence for a major unconformity to divide and so practically eliminate the Botniahalvoya Supergroup. Isotopic ages for all Svalbard included earlier data for Nordaustlandet (e.g. Hamilton & Sandford 1964; Gayer et al. 1966; Edwards 1976; Edwards & Taylor 1976).

Minor igneous bodies, 106

6.5.1 Acid intrusions, 106 6.5.2 Basic layers to northeast, 106 6.5.3 Dolerite sills and dykes, 106 Summary of isotopic ages, 106 Structure of Nordaustlandet, 107

6.7.1 A Barents craton, 108 6.8

The Lomonosov Ridge in relation to Nordaustlandet, 108

Quaternary studies were undertaken but are discussed in Chapter 21 (e.g. Salvigsen 1978). Various geological maps and accompanying descriptions consolidated the information as follows: 1:500 000.3G (Hjelle & Lauritzen 1982) and 4G (Lauritzen & Ohta 1984, and I:IM Bedrock Map (Winsnes 1988). Russian work was included by Krasil'shchikov (1967) and in his Precambrian synthesis (1973). Sundry visits in western Nordaustlandet added miscellaneous observations by Cambridge parties (Knoll 1982a, 1984; Hambrey 1982; Hambrey, Harland & Waddams 1981; Harland, Hambrey & Waddams 1993).

6.2

Stratal succession

Confining the study area in this chapter to the land north of about 79~ t, with few exceptions all the exposures to the north are of preCarboniferous and all to the south are of post-Devonian rocks. The exceptions include dolerite intrusions of probable Cretaceous age and one outcrop of Carboniferous/Permian strata at Idunfjellet, north of Wahlenbergfjorden. It has been convenient to include consideration of these exceptions in (the preceding) Chapter 5. The sequence of strata as worked out by Kulling (1932/4) and by Norsk Polarinstitutt geologists (e.g. Flood et al. 1969; & Ohta 1982), modified by Gee et al. (1995) is compiled in Fig. 6.2. The origin of the names in the evolving scheme is discussed here and adopted for descriptive purposes. (1) On the names. From Kulling's classic work the names Kap Sparre, Murchison Bay, and Kap Hansteen were introduced in 1932 in the first Swedish report using Swedish place name spellings. His full report with definitions was in English (1934) with Cape Sparre, Murchison Bay and Cape Hansteen. The original Swedish names have been generally followed but often mistakenly edited into the Norwegian spelling of Kapp for Kap, whereas the Norwegian place name is Sparreneset. In this work Sparreneset formation is introduced for what is only a part of the original Kap (Cape) Sparre Formation to avoid ambiguity which, unfortunately, was not done by Harland, Hambrey & Waddams (1993). Similarly the revision e.g. by Lauritzen & Ohta (1984) limits radically the meaning of the original Kap Hansteen Formation to a part of it, namely their Kapp Hansteen Formation. The new spelling is intended for the units as they have been revised; but the English form is used in discussion when referring to Kulling's units as he described them. Krasil'shchikov (1967) described the tillite-like rocks of Nordaustlandet with a radical redivision of Kulling's scheme. This was accepted by Harland (1985) and Harland et al. (1993) but with mistaken application of two names that are corrected here. However the major Norsk Polarinstitutt geological exploration of Nordaustlandet carried out in 1965 when published did not take account of Krasil'shchikov's work (Flood et al. 1969). The following notes attempt to clarify a confusing nomenclature in a rapidly developing geological understanding as shown in Fig. 6.2.

N O R T H E R N NORDAUSTLANDET

97

Fig. 6.1. Map of northern Nordaustlandet showing principal topographic features, ice-rock boundaries and major place names. (1) Adlersparrefjoren; (2) Bodleybukta; (3) Botnvika; (4) Bragerbreen; (5) Bragneset; (6) Depotodden; (7) Ekstremhuken; (8) Gimterbreen; (9) Gylde~n6yane; (10) Holmboeodden; (11) ldunneset; (12) Isrundingen; (13) Kapp Fanshawe; (14) Kapp Lady; (15) Kapp Laura; (16) Kapp Lindhagen; (17) Kapp Lord; (18) Krossoya; (19) Langgrunodden; (20) Lindhagenbukta; (21) Maudbreen; (22) Nilsenbreen; (23) Nordporten; (24) Nordre Franklinbreen; (25) Normanbreen; (26) Oxfordhalvoya; (27) Pentavika; (28) Rijpbreen; (29) Ringertz6ya; (30) Schweigardbreen; (31) Selanderneset; (32) Sore Franklinbreen; (33) Svartneset, (34) Zeipelodden.

(i) Kulling's (1932, p. 142) preliminary scheme:

His full scheme with descriptions in 1934:

'Kap Sparre-formationen Sveanor-formationen Murchison bay-formationen Kap Hansteen-formationen Prim~irt liggende Ok/int.' (Primary layers unknown)

Cape Sparre Fm Sveanor Fm Murchison Bay Fm Cape Hansteen Fm

(ii) Hinlopenstretet Supergroup as defined just across the strait in Ny Friesland (see Chapter 7), for the Oslobreen and Polarisbreen groups (Harland, Wallis & Gayer 1966). The upper carbonate part of Kulling's (original Cape Sparre Formation has proved to be the equivalent of the Oslobreen Group with an Early Cambrian Krossoya unit and an Early Ordovician Sparreneset unit (informally introduced here). Krasil'shchikov's (1967) revision distinguished his Gotiahalv~ya Group (equivalent to the Polarisbreen Group) by making three formations that are equivalent to the three formations in the Polarisbreen Group as follows. The Klackbergbukta Formation (the equivalent of the Dracoisen Formation in Ny Friesland comprises the upper pelitic part of Kulling's Cape Sparre Formation. The Sveanor Formation follows Kulling and corresponds to the Wilsonbreen Formation in Ny Friesland The Backaberget Formation of Krasil'shchikov (equivalent to Ny Friesland's Elbobreen Formation) is the lower pelitic part of Kulling's Ryss6 Formation. ('fii) Kulling's (1932) Murchison Bay, rather than Murchisonfjorden of Flood et al. (1969), is retained as the name for this supergroup on the basis that whereas he did not distinguish the Franklinsundet Group formations

(thinking they repeated younger rocks in the opposing limb of an isoclinal fold, he nevertheless did include these rocks in his Murchison Bay unit, a name that has been widely used. (iv) The Cape Hansteen Formation of Kulling was widely used as the name for the rocks older than the Murchison Bay succession. Flood et al. (1969) in effect divided Kulling's Cape Hansteen Formation into two: the Kapp Hansteen Formation with a conspicuous acid volcanic component and the Brennevinsfjorden Formation largely of shales and sandstones. They noted a conglomerate between but were not certain which of the formations was the younger, opting tentatively (but as it proved mistakenly) for the Brennevinsfjorden Formation as the younger. They combined the two formations into the Botniahalvoya Group which was indeed Kulling's Cape Hansteen Unit. However, Ohta (1982) demonstrated that the Kapp Hansteen volcanic sequence rested with angular unconformity above the Brennevinsfjorden siliciclasts. This evidence was presented in more detail by Gee, Johanssen, Ohta et al. (1995) which scheme is followed here. The conclusion is that a significant folding episode divided the Botniahalvoya Group which therefore ceased to be a useful unit and Gee et al. instead transferred the name Botniahalvoya to the unconformity, and so presumably to the diastrophism. (v) Meyerbnkta and Austfonna rocks. There is some difficulty over the correlation of the extensive outcrops around Rijpfjorden and to the east. These were mapped by Flood et al. (1969) as the Austfonna Formation in the south and the Kapp Platen Formation in the north and were included at the top of their Botniahalvoya Group. However, Ohta (1982) in extending downwards the Murchison Bay Supergroup included within the outcrops on L~tgoya his new Meyerbukta Formation at the base. He then appeared to define it as a group by including the three formations of the Austfonna Group which he tabulated (p. 44) within his Murchisonfjorden Supergroup. Lauritzen & Ohta (1984) also

NORDAUSTLANDET Formation

Group

NY FRIESLAND Supergroup

Group

Sparreneset 100 (10-17) Kross~ya (10-17) Klackbergbukta 650 (6) Sveanor* 300 (2) Backaberget 290 (6)

Formation Valhallfonna (8)

Oslobreen 1200 (3)

Kirtonryggen (5) Ditlovtoppen (5)

Hinlopenstretet (11) (5) Gotiahalv~ya (6)

Polarisbreen 9OO (3)

Dracoisen (5) Wilsonbreen (5) Elbobreen (5)

Roaldtoppen (7)

Akademiker -breen 1350-2400 (3)

Backlundtoppen (3) Draken (3) Svanbergfjellet (5) Grusdievbreen (5)

Ryss~* 750 (1-2) Hunnberg* 500 (2)

Oxfordbreen (3)

Raudstup-S~ilodd* 550 (2) Norvik* 340 (2)

Celsiusberget (7)

Flora* 1250 (2)

Murchison Bay* (2)

I.o v t--

o ~0

~, E

Kapp Lord 1000 (7)

Glasgowbreen (5) Veteranen 3800 (3)

0 ..1

Westmanbukta 625 (7)

Kingbreen (5) Franklinsundet (7)

Persberget >150 (7) Meyerbukta (9)//~C~.ntr~" in i^1 / ...... "" J(Innvikhogda) ? j/ 400 m

Basal quartzite (9) -(-Ausffonna in C---

_ 9

Kontaktberget g. (13.) / ~ 1 6 ] Laponiahalv~ya ~ (13) 9 -Rijpdalen Laponiat]ellet g. (13)~ra~it-~s granites (13-16) ~ (16) Quartz porphyry, porphyrite, acid andesite and ~ tholeiite volcanics / / / i n Kapp and intrusive f m s j centre Hansteen inW ~ v " ..ane 2000(7) a J Botnia(16) ~-~-f~.~-~-~ ~/ halv~ya Upper sst. and sh. (9) in W , ~unconf. (13) Middle qtz. and sh. (9) ~ Lower sh. and sst. (9) ~ in centre BrennevinsBasal quartzite// fjorden >3000 (7) ( 9 ) ./ Helvetsflya _ ~ _ (16) _ Migmatites with gneisses and granites of Proterozoic age intrusive into above two groups 1950_10501 (16) Paragneiss and paleosomes in Duvefjorden Complex (12) (=metamorphic complex of Sandford 1956)

Kortbreen (5)

__

Vildadalen (5) Planetfjella 4750 (3) Fl~en(5) "-p ,-, ~ O "~ .o'= ~

i

,

9

r ,- .

Harkerbreen 4150 (3)

.

. ~ ~

.

i

,

(19) (14) Atomfjella Complex (4)

Finnlandveggen 2700 (3) ?,~Jv~,_, ?

~

(18)

Granitoids

~

(15)

Fig. 6.2. Preferred names for rock units in Nordaustlandet and their approximate equivalents in Ny Friesland, with estimated thicknesses in metres, mainly based on Harland (1997, table 2) with permission of Norsk Polarinstitutte. The origin of the names is indicated by the numbers in brackets: (1-2) Nordenski6ld in Kulling (1934); (3) Harland & Wilson (1956); (4) Abakumov (1965); (5) Harland et al. (1966); (6) Krasil'shchikov (1967); (7) Flood et al. (1969); (8) Fortey & Bruton (1973); (9) Ohta (1982); (10) Lauritzen & Yochelson (1982); (11) Lauritzen & Ohta (1984); (12) Gramberg, Krasil'shchikov & Semevskiy (1990); (13) Gee et al. (1995); (14) Johansson, Gee & Larionov (1995); (15) Larionov et al. (1995); (16) Gee & Teben'kov (1996); (17) this work. The Kapp Hansteen Group is defined by two formations in Botniahalvoya: Norgekollen (quartz porphyry) Formation, above and Gerarodden (volcaniclastics) Formation below, and in the Rijpdalen area it would include the Svartrabbane Formation as plotted. *, detrital zircons indicate maximum age of Strata: (18) Gee & Hellman (1996); (19) Hellman et al. (1997).

NORTHERN NORDAUSTLANDET showed the Meyerbukta Group as equivalent to the Austfonna Group in the east. However, already Flood et al. (1969) had shown that the Austfonna Formation was not only intruded by quartz porphyry but also cut by the Rijpfjorden granite. Moreover they had shown it to be continuous with the Brennevinsfjorden Formation, which was, however, then thought to lie above the Kapp Hansteen Formation. The outcome must be that the Austfjorden and Kapp Platen formations are older than the Kapp Hansteen Group and correlate with and belong to the Brennevinsfjorden Group whereas the Meyerbukta Unit is clearly the lowest unit so far recorded within the Murchison Bay Supergroup. It cannot thus be defined by the Innvikhogda, Djevlaflora and quartzite formations of the Austfjorden Group but rather as its own formation which is included here within the Franklinsundet Group as the rocks were originally so included by Flood et al. (1969). This has been clarified by Gee et al. (1995), Larionov et al. (1995) and Gee & Teben'kov as Fig. 6.2. (vi) The Granites. The granites were originally thought to be ancient but the relatively unfoliated and pink rather than grey granites generally appear to have intrusive contacts and would therefore be younger than the adjacent rocks. By analogy with the granites in northwest Spitsbergen which Holtedahl argued were 'Caledonian', it was thought by Kulling, and by most geologists until recently that the late tectonic granites would also be Paleozoic. Indeed isotopic investigations supported this view as shown in the compilations of Gayer et al. (1966) and Ohta (1992). Values consistently averaged around 400 Ma mostly by K - A r and Rb-Sr determinations mainly on biotite, muscovite and whole rock. However, the application of uranium-lead isotopic studies of zircons opened a new window on the problem. Many apparently younger granites are now yielding ancient zircons. Therefore if the zircons represent the age of original cooling of the granites it appears that many Precambrian granites have been subject to later, Paleozoic reheating. Making the assumption that the zircons were not inherited from an older basement we now have the prospect of a radical reinterpretation of the Nordaustlandet granites as Proterozoic (Gee et al. 1995; Larionov et al. 1995; Gee & Teben'kov 1996). (vii) The migmatites. Increasingly eastwards migmatites prevail. They invade older strata of which fragments of a ghost stratigraphy may be interpreted. They are clearly older than, through probably related to, Prins Oscars Land granites and probably the Laponiahalvoya granites. They would thus appear not to be Caledonian migmatites although modified in Paleozoic time, but rather developed from migmatites associated with the Kapp Hansteen magmatic events. (viii) Duvefjorden Complex. This name introduced by Teben'kov (Gramberg, Krasil'shchikov & Semevskiy 1990) usefully signifies the metamorphics, migmatites and granites east of Rijpfjorden, whose age is not established. It probably represents the Precambrian Barents Craton.

6.2.1

Hinlopenstretet Supergroup

This s u p e r g r o u p is set o u t here as c o m p r i s i n g t w o groups.

Oslobreen Group Sparreneset formation (informal) Krossoya formation (informal)

Gotiahalvoya Group Klackbergbukta Formation Sveanor Formation Backaberget Formation T h e H i n l o p e n s t r e t e t S u p e r g r o u p was defined in N y F r i e s l a n d to the west o f H i n l o p e n s t r e t e t ( H a r l a n d , Wallis & G a y e r 1966) c o m p r i s i n g the O s l o b r e e n G r o u p ( C a m b r o - O r d o v i c i a n f o r m a t i o n s ) a n d the P o l a r i s b r e e n G r o u p ( V e n d i a n f o r m a t i o n s i n c l u d i n g tillite horizons). Similarly o u t c r o p s in N o r d a u s t l a n d e t o n the east side o f H i n l o p e n s t r e t e t were described earlier by K u l l i n g as the C a p e Sparre F o r m a t i o n a n d the S v e a n o r F o r m a t i o n respectively. T h e C a p e Sparre F o r m a t i o n (850 m) was divided by K u l l i n g (1934) i n t o six series ( m e m b e r s ) thus: (6) (5) (4) (3) (2) (1)

Upper Upper Upper Lower Lower Lower resting

D o l o m i t e , 140-200 m Quartzite, 110 m Shale 1 3 0 - 1 4 0 m Dolomite 120m Quartzite 30-40 m Shale 250 m. o n the S v e a n o r (tillite) F o r m a t i o n .

99

Winsnes (Flood et al. 1969) redescribed and measured further sections of this unit which he renamed the Kapp Sparre Formation in the same arrangement, but increasing the thickness estimate to 1200 m. This scheme was followed by Lauritzen & Ohta (1984). A more detailed section of the Sveanor Formation was recorded by Edwards (1976). Krasil'shchikov (1967, 1973) had also recorded sections and redivided the succession so that Kapp Sparre Formation was limited to Kulling's division (6) above and the remainder was named Klackbergbukta Formation. This reclassification was followed by Harland (1985) and again by Harland, Hambrey & Waddams (1993), but mistakenly mistranslating the name Klackberget. Krasil'shchikov's Blackaberget Formation (which constitutes the upper pelitic part of Kulling's Rysso dolomite Formation) was also accepted by Harland et al. These revisions have the advantage of distinguishing an upper Early Paleozoic carbonate unit, a Vendian siliciclastic unit and a (mainly) preVendian carbonate unit. The upper two units correlate well with the Oslobreen and Polarisbreen groups in Ny Friesland and so this classification is applied. It is thus appropriate to rename the original Cape Sparre Formation by dividing it into the Sparreneset and the Klackbergbukta formations. Similarly the Ryss6 Formation as defined by Kulling loses its upper part to make the Backaberget Formation. Thus Krasil'shchikov's (1967) three (Vendian) formations combine to define his Gotiahalvoya Group (equivalent to the Polarisbreen Group of Ny Friesland) and so form the lower group of the Hinlopenstretet Supergroup as applied in Nordaustlandet by Lauritzen & Ohta (1984). T h e r e c a n be n o d o u b t as to the c o r r e l a t i o n w i t h N y F r i e s l a n d as s h o w n in F i g u r e 6.2.

Oslobreen Group. This group, named for the Ordovician and Cambrian formations in Ny Friesland as the uppermost of the two groups comprising the Hinlopenstretet Supergroup, is applied here for the time being pending a decision as to whether the equivalent strata in Nordaustlandet require a distinct group name. It is the uppermost unit 6 of Kulling's Cape Sparre Formation. He described this upper dolomite series (140-200 m) thus: at Sparreneset: Black grey dolomitic mudstone, 40 m with trail marks (originally observed by de Geer 1901, and identified as Helminthoidichnites) and inarticulate brachiopods (Lingulella and Obolus) Grey dolostone, 70-100 m. on Krossoya: Grey to dark-grey dolostone, with trail marks in upper part (Planolites) on Depotoya up to 700 m but poorly exposed. All these fossils have long time-ranges so no precise biostratigraphic correlation could be made, though Kulling took the age to be Early Cambrian. Winsnes (in Flood et al. 1969) described a further section north of Br~vika and measured others. At Sparreneset, in 1974, Harland found the contact with the earlier rocks to be faulted (Hambrey, Harland & Waddams 1981). He thought the nearest analogue in Ny Friesland to be the Nordporten Member of the Valhallfonna Formation of demonstrable Arenig a g e - just across Hinlopenstretet. More fossils had been sought in vain by several parties, but outcrops are between tides and of limited extent. He also noted a fault so that two formations could be present there. The difficulty was resolved by Lauritzen & Yokelsen (1982) who recorded Salterella at Sparreneset, and in Krossoya they also found olenellid tribolites so confirming a late Early Cambrian age. Moreover west of Krossoya they reported an Early Ordovician fauna so supporting Harland's suggestion. Until the matter has been taken further the Early Ordovician unit is referred to informally as the Sparreneset unit to distinguish it from the Early Cambrian Krossoya Formation, the names selected where ages are evident. The result is to match still more closely the successions in Nordaustlandet with those in Ny Friesland. Undifferentiated sections were measured by Kulling (1934) as about 500 m at Sparreneset and by Winsnes (Flood et al. 1969 p.20) at over 1100 m north of Br~tvika near the northwest of Storsteinhalvoya. Sparreneset (informal) formation. Lithologically at Sparreneset this would correlate with the Nordporten Member of the Valhallfonna Formation which in Ny Friesland is of late Canadian (Arenig) age. Biostratigraphically Lauritzen & Yochelson (1982, p.5) reported: 'on small islands northwest of Krossoya, an Ordovician fauna has been found indicating a break in the succession from Middle Cambrian to lower Ordovician time...'. The two unnamed islands near to the northwest coast of Krossoya were mapped by Kulling (1934) as part of his Cape Sparre Formation. Sparreneset is where Harland had noted this unit. No measured section has been published.

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Krossoya (informal) formation. This name is chosen for that part of the uppermost three units of Kulling's Cape Sparre Formation because it appears to be best developed there with a thicknesses of 700-800 m and was described there by Kulling and in 1966 by Winsnes (in Flood et al. 1969) and who collected the specimens identified by Yochelson (Lauritzen & Yochelson 1982) as Salterella. Olenellids were also found so that good correlation is established with the Tokammane Formation of Ny Friesland which, together, indicate a late Siberian (Early Cambrian) age i.e., the Bonnia-Holmia zone. At Sparreneset the succession was described by Kulling (1934) as containing Lingulella and Obolus types and with trace fossils: Helminthoidichnites type and estimated at 110 m in difficult circumstances thus (p. 191): 40 m black-grey dolomite mudstone with trail marks and brachiopods 70-100 m grey dolomite 3 m black-grey laminated dolomites. This may well include part of the Sparreneset formation. The section is clearly incomplete dipping west into the sea. Gotiahalvoya Group (Krasil'shchikov 1967) (equivalent to the Polarisbreen Group of Harland & Wilson 1956). The group comprises three formations: Klackbergbukta (top), Sveanor and Backaberget. Krasil'shchikov (1967) recorded the most detailed available petrographic description of these deposits, only some portions of this are added to this account. Klackbergbukta Formation (Krasil'shchikov 1967). This unit comprises the lower five units of Kulling's (1934) Cape Sparre Formation which he described thus: (5) Upper quartzite series, l l 0 m of variously coloured (red, grey, green, white) quartzite and slaty sandstone at Sparreneset and on Krossoya, also with some grey dolomitic mudstone. (4) Upper Shale Series, 130-140m, pink and grey shales with laminated dolostone and bands of chert (a thin middle quartzite occurring only on Krossoya). (3) Lower Dolomite Series, 120m. At Sparreneset, dark and black-grey dolostone also with some dolomitic limestone on Krossoya and Depotoya. (2) Lower Quartzite Series, 30-40m. White quartzite sandstone only at Sparreneset (subjacent rocks are not exposed possibly being tectonically disturbed). (1) Lower Shale Series, 250m. Green grey and red brown shale SW of Sveanor on S Russoya but more carbonaceous with 10 m dolostone at base resting directly on Sveanor tillite. Other outcrops in Murchisonfjorden and Wahlenbergfjorden were outlined by Winsnes (in Flood et al. 1969), Edwards (1976) and summarized by Harland, Hambrey & Waddams (1993). The age of these rocks has been confirmed as probably Vendian (Knoll 1982a). The dolostones of the upper horizons of the formation are characterized by flaggy parting with thin impersistent layering separated by a few mm of dolomitic siltstones. Krasil'shchikov described centimetre-scale 'convective' ruptures in the lamination, forming regular polygons in plan. Limonitized pyrite occurs higher up. The sandstone clasts are 90%, acid plagioclase dominating orthoclase with a wide range of accessory minerals. Below a sharp boundary are light coloured sandstones. Sveanor Formation (Kulling 1934), 100-168 m. At the type locality, south of Murchisonfjorden, is a diamictite which was the first in Svalbard to be identified unequivocally as a tillite and has been described in detail (Kulling 1934; Edwards 1976; Hambrey 1982). Whereas Flood et al. (1969) included part of Kulling's Rysso Formation, Krasil'shchikov (1967) distinguished that part as his Backaberget Formation (below). This classification is adopted here and so Kulling's Sveanor Formation is approximately retained. Within the formation lateral facies changes are m a r k e d - the typical tillite is best seen at Sveanor in Murchisonfjorden and at Aldousbreen in Wahlenbergfjorden. The diamictites, interbedded sporadically with sandstones, shales and carbonates, range in colour from greyish and green to maroon. The stones comprise: dolostone (50%), limestone (20%) and the rest sandstone, siltstone, granite, granite porphyry, aplite, quartz porphyry, syenite, keratophyre, amygdaloidal basalt, tuff, siliceous sericitic schist, garnet schist, gneisses, phyllite, quartzite, basic volcanic rocks and jasperised chert (Kulling 1934). The proportion of stones is about 5-10%. All shapes especially facetted and striated (up to 10%) stones being common. Krasil'shchikov described the stone petrography in detail noting oncolitic concretions and concretions with katagraphs. The facies vary from massive to weakly bedded diamictite, with conglomerate lenses. The environment of formation is interpreted as

lodgement and waterlain till deposit and ice rafted stones in more distal mudstones, all indicating an interplay of subaerial, subglacial, glaciomarine and glaciolacustrine and fluvial environments. The cessation of glacial conditions is marked by the sharp change to the Klackbergbukta Formation (Harland, Hambrey & Waddams 1993). The till facies were described by Chumakov (in Krasil'shchikov 1964) before he had accepted a glacial origin for such deposits. Many pages are filled with meticulous petrographic descriptions with few petrogenetic (environmental) conclusions. Selected from this account is the estimate that the larger intrabasinal clasts (stones) suggest local origin from the underlying formations down only to a maximum of 500 m. They confirmed Kulling's view that the basic volcanism preceded, but not by a long interval, the deposition of the diamictites. These basic igneous products unlike many of the acidic rocks were not metamorphosed. Attempts to deduce provenance of the stones were not productive. Krasil'shchikov and others correlated these Sveanor rocks with the Polarisbreen rocks acknowledging that Harland & Wilson (1956) had inferred a glacial origin for the same correlation as had Kulling for the Sveanor Formation. But having considered a glacial origin they preferred (with Klitin 1965) a purely tectonic origin for all such deposits. Baekaberget Formation (Krasil'shchikov 1967), 220-290m. Krasil'shchikov separated this unit from the top of Kulling's Sveanor Formation. Hambrey, Harland & Waddams (1981) and Harland, Hambrey & Waddams (1993) followed this scheme, partly because it correlated well with the succession to the west in Ny Friesland. The formation, based on Kulling's 1934 units east of Sparreneset comprises (4) 50 m laminated, cream-weathering, grey, partly cross-laminated dolostone with rip-up conglomerate at the top (3) 40m dark-grey quartzose slate (2) 150 m grey-black shale (15-20 m dolerite sill) (1) no exposure.

Langgruneset member. To the north at Langgrunnodden is a diamictiterhythmite-limestone-sandstone sequence included by previous authors in the Sveanor Formation. However, because of its distinctive composition (dolostone 65%, limestone 15%, quartzite 10% etc.), it appeared to correlate well with the Petrovbreen Member of the Elbobreen Formation in Ny Friesland (Hambrey 1982) and so would be the equivalent of the Early Varanger tillite (Smhlfjord). The diamictite is underlain by dark, cherty shaly limestone (10m), several tens of metres of marls, sandy towards the base overlying the Rysso dolostone. Well preserved acritarchs in the shales yielded to Knoll (1982a): Protosphaeridium sp., Trachysphaeridium spp., cf. stictosphaeridium sp., and Bavinella faveolata (Shepeleva) which indicate a Vendian age. Osagia svalbardica and Vermiculites irregularis had also been reported in Soviet literature (Krasil'shchikov, Golovanov & Mil'shtein 1965).

6.2.2

Murchison Bay Supergroup (Kulling 1932, 1934)

This s u p e r g r o u p n o w c o m p r i s e s three g r o u p s defined by their f o r m a t i o n s as follows, a n d illustrated in Fig. 6.3. Roaldtoppen Group Rysso Formation Hunnberg Formation Celsiusberget G r o u p Raudstup-Salodd Formation Norvik Formation Flora Formation Franklinsundet Group Kapp Lord Formation Westmanbukta Formation Persberget F o r m a t i o n Meyerbukta Formation K u l l i n g ' s (1934) M u r c h i s o n Bay f o r m a t i o n was raised in r a n k to a s u p e r g r o u p a n d r e n a m e d M u r c h i s o n f j o r d e n by F l o o d et al. (1969) in w h i c h K u l l i n g ' s original six 'series' were a d o p t e d as five f o r m a t i o n s b u t classified into two g r o u p s . T h r e e m o r e f o r m a t i o n s were defined at the base o f the succession for rocks t h o u g h t by

NORTHERN NORDAUSTLANDET

Fig. 6.3. Geological map of northwestern Nordaustlandet (after Flood et al. 1966; Gee et al. 1995).

101

102

CHAPTER 6

K u l l i n g to be repetitions by folding o f his lower f o r m a t i o n s a n d c o m b i n e d in the F r a n k l i n s u n d e t G r o u p . A f o u r t h unit was i n t r o d u c e d ( O h t a 1982) to a c c o m m o d a t e f u r t h e r strata below the F r a n k l i n s u n d e t G r o u p a n d to include the K a p p P l a t e n a n d A u s t f o n n a f o r m a t i o n s east o f R i j p f j o r d e n also within the s u p e r g r o u p .

Roaldtoppen Group (Flood et al. 1969). Both constituent formations were argued to be late Riphean (Knoll 1982). Rysso Formation (Nordenski61d 1863; Kulling 1934) was modified by Krasil'shchikov (1967) who, as already noted, placed the upper part of Kulling's Rysso Formation in his Backaberget Formation. The essential Ryss6 Formation middle and lower part is of relatively uniform massive dolomitic facies. Only this part was described as the Rysso Formation by Winsnes (Flood et al. 1969). It is one of the earliest formations to be named in Svalbard but not at first defined. It was probably the whole carbonate development of the Roaldtoppen Group and was thought to be Carboniferous (Nordenski61d 1863): 50-140m light grey dolomite 70-140 m dark dolomitic limestone - dolomite 500 m typical Ryss6 - dolomite (conspicuously oolitic and stromatolitic). The lower part contains yellow-weathered chert, further details were given by Winsnes and by Krasil'shchikov. Krasil'shchikov, Golovanov & Mil'shtein (1965), describing the biostratigraphy, recorded Vermiculites irregular& with a range Vendian through Cambrian. Silicified bituminous limestones with pyritic black shales near the top of the Ryss6 Formation contain vase-shaped microfossils which suggest correlation with the Backlundtoppen Formation in Ny Friesland and the upper Eleonore Bay carbonates in East G r e e n l a n d - all in the Sturtian interval (?750 Ma). Silicified carbonates in lower Ryss6 Formation match the biota of the Hunnberg Formation below, but have Chuaria in addition (Knoll 1982). Hunnberg Formation (Kulling 1934) 400-600m. Consists predominantly of grey black and grey limestones and dolomitic limestones, passing into mudstones, with lighter coloured, and subordinately reddish, limestones in the middle part. There are horizons of chert concretions, chert conglomerates and phosphorite concretions. The upper part of the formation is a shallowing-upward carbonate sequence passing upwards into open coastal marine facies with bioherms and columnar stromatolites overlain by laminated mud-cracked dolostones. The cherts contain microfossil assemblages (Knoll 1982). The restricted lagoonal biota is dominated by Myxococcoides cantabrigiensis Knoll (1982a) and Glenobotrydion aenigmatis Schopf (1968). The open coastal assemblage is a rich variety of plankton including: Chuaria circularis Walcott, Protosphaeridium cf flexulosum Timofeev (sensu Vidal 1976a), Kildinella hyperboreica Tim. K. jacutia Tim. Trachysphaeridium levis (Lopukhin) Vidal, Trachysphaeridium timofeevi Vidal, cf Stictosphaeridium, Phanerosphaerops capitans Schopf, Myxococcoides cantabrigiensis Knoll. Trematosphaeridium holtedahlii Tim. (Knoll 1982). This is a typical Late Riphean microfossil assemblage. The lowest first occurrence of pterospermopsimorphid acritarchs and other complex taxa suggest latest Riphean to Early Vendian (sensu Vidal). Knoll suggested 700800 Ma for the age. Organic geochemistry of the Raoldtoppen Group. In a s t u d y o f dispersed organic m a t t e r in P r e c a m b r i a n deposits o f N o r d a u s t l a n d e t , D a n y u s h e v s k a y a et al. (1970) analysed samples f r o m the R o a l d t o p p e n G r o u p a n d f o u n d t h a t clots o f biogenic c a r b o n a c e o u s material t e n d e d to be c o n c e n t r a t e d in stylolitic structures. T h e y also analysed basal (Vendian) K l a c k b e r g b u k t a a n d B a c k a b e r g e t strata f r o m the overlying H i n l o p e n s t r e t e t S u p e r g r o u p . Many data were tabulated including total organic carbon thus: Klackbergbukta Fm Backaberget Fm Ryss6 Fm (upper member) Hunnberget Fm

0.49% 0.54% 1.07% 0.19%

With transmitted light the organic matter is dark grey through brown to black, in reflected light it is whitish yellow to dark brown. UV luminescence studies showed the dark brown to black matter to be inert and surrounded by an inner luminescent dimly green aureole passing outwards to lighter luminescence. The black material was unevenly pyritized.

Spectroscopic analysis with (many detailed spectra reported) indicated abundant aromatic structures with linked carboxylic C = O groups possibly with (?)chione affinity and a significant aliphatic component of CH2 and CH3. The conclusion was that the material had resulted from the transformation of blue-green algae in the first instance in the Ryss6 carbonates and that at a later stage (a Caledonian event was suggested) fractionation with migration of the lighter hydrocarbon components into the overlying Vendian sandstones accounted for much of the TOC in those formations. In a final comment the authors remarked that their'results paralleled those from North America and Greenland.

Celsiusberget Group (Flood et al. 1969) Raudstup-Siilodd Formation (Kulling 1934; Flood et al. 1969). Kulling described two series in Murchisonfjorden (especially the north coast): (upper) Siilodd series (180-260) of greenish-grey dolomitic siltstones or redgrey shale of Ohta 1982; (lower) Raudstup series (300-440m) of reddish brown and green-grey slate partly carbonaceous and also quartzose with horizons of white quartzose sandstone. Flood et al. (1969) combined these two series into one formation because the lithologies are interbedded and there is no clear boundary between them. The formation occupies the core of the major synclinorium and thicknesses vary greatly from 400 to 2200 m (Ohta 1982). Small scale cross-bedding in the sandstones suggests a wave-dominated sub-littoral environment. Four fining-upward cycles were distinguished in the lower less deformed strata. A metaporphyrite stratum, 0.5 m with plagioclase and mafic phenocrysts (?after pyroxene) occurs in the lower part and is either an intrusive sheet or a lava flow. It is too altered to compare with the widespread Mesozoic dolerites (Ohta 1982). Norvik Formation (Kulling 1934) 350 m is of dominant green-grey to grey sandstone and slaty sandstone dolomite. Multicoloured slates and white quartzite also occur. Ohta (1982) described it as a formation of 900m of lithology intermediate between the overlying shale-rich formation and the thick Flora quartzites with two members: (upper) shale and quartzite alternation (300-700m); (lower) shale-dominated succession (200-550m) and with five cyclic sequences, the quartzite being 7-20 m thick at the base of each cycle. Flora Formation (Kulling 1934) 910m was described by Kulling: as the distinctive lower unit of his Murchison Bay succession, comprising white, pink and green-grey quartzose sandstone. 630m were measured at Floraberget in 13 divisions. Ohta (1982) gave a thickness of 910m divided into three members with detailed petrographic descriptions: (upper) white grey banded ortho-quartzite with thin flasers of shale and sandstone 50-150 m (middle) reddish quartzite with shales and slates and red shale fragments (lower) alternations of grey sandstone and reddish-white quartzite with abundant red shale fragments. There is a basal conglomerate Franklinsundet Group (Flood et al. 1969). The strata described here beneath the Flora Formation were included by Kulling in his Murchison Bay rocks, but assumed to be repetition of the younger strata by folding because of their similar facies. He perhaps exaggerated the steepness of dips in his postulated isoclinal folding. Flood et al. distinguished three older formations combined in the new grouping. Still older strata were distinguished by Ohta (1982: his Meyerbukta formation) and included at first in the Franklinsundet Group. However, Lauritzen & Ohta (1984) named a further Meyerbukta Group. These two new groups may total nearly the same thickness as the two upper groups of the Murchison Bay Supergroup. The upper two formations of the Franklinsundet Group are clearly distinguished from the conspicuous quatzites above (Flora) and (Persberget) below and it is not easy to distinguish the upper two formations as their mutual boundary is not well exposed. Kapp Lord Formation, 1000 m, in which a detailed succession of 43 units recorded by Gee (Flood et al.) comprising mudstones (various colours) quartzites, limestones and shales in that order of abundance. Westmanbukta Formation, 625 m is similar to Kapp Lord Fm. but with less limestone and more siltstone and fine sandstone. Persberget Formation is characterized by massive white and grey quartzite with subordinate grey shales and ripple marks and ferruginous spots. No complete section was measured and this may account for the lower part being underestimated (Flood et al.) which was later distinguished as the Meyerbukta Formation. Meyerbukta Formation (Ohta 1982). To the north of Kapp Lord and Westmanbukta, the large island of LAgoya yielded to Ohta (1982) a

NORTHERN NORDAUSTLANDET thickness of shales, east of and below the Persberget quartzites. The shales are in places calcareous and grey limestones occur. Ohta claimed 1400m in total for this Meyerbukta Formation. He also (1982 p. 29) argued for a series of megacycles into which the above successions could be divided. Djevleflota Formation (Ohta 1982; Gee & Teben'kov 1996). In central Nordaustlandet in the outcrops between Austfonna and Vestfonna and south of Rijpfjorden to inner Wahlenbergfjorden, Ohta had described three units: Innvikhogda, Djevleflota and a basal quartzite. The area was mapped in greater detail (Gee & Teben'kov 1996) which resulted in a revised stratigraphic scheme.The Djevleflota Formation was accepted as correlating with Ohta's Meyerbukta Formation in the west and at the base of the Murchison Bay Supergroup. In this area it was seen to rest unconformably on the Svartrabbane Formation correlated with the Kapp Hansteen Group. This formation is essentially the same as the Austfonna Formation originally mapped here (Flood et al. 1969).

6.2.3

Kapp Hansteen Group

Botniahalvoya. (Kulling 1932, 1934; Ohta 1982; Lauritzen & Ohta, 4G, 1984). The group comprises at least the Norgekollen and Gerardodden formations (introduced informally here to define the Kapp Hansteen Group), and probably includes the Svartrabbane Formation (Gee & Teben'kov 1996). Kulling (1934, p. 221) summarized his Cape Hansteen Formation as 'of considerable but little known thickness. Grey-green to green porphyry dominates the formation, but there are also violet-grey to red-grey porphyry, grey quartz-porphyry, greengrey quartz-phyllite (mostly more or less rearranged pyroclastic material), agglomerate, and conglomerate'. He gave detailed descriptions area by area. Flood e t al. (1969) described the petrographic types in the volcanogenic Kapp Hansteen succession. In spite of their uncer tainity as to the relative ages of the Kapp Hansteen and Brennevinsfjorden units they were clear that the magmatic rocks best seen around Norgekollen were later, being intrusive into the fragmental Kapp Hansteen succession. Ohta (1985) described the geochemistry of the igneous rocks in detail. He concluded that 'the porphyrites are calc-alkaline acid andesites and dacites of medium to high KaO type'. Two meta-diabase types are (i) of low K20 and high Fe tholeiite and the main body (ii) are acid andesites. Basic dykes suggest island arc volcanism and all are referred to continental rather than oceanic types.

Norgekollen (quartz porphyry) Formation. This is the large body cropping out at Norgekollen but representative of other quartz porphyry intrusions in the peninsula. Whereas it intrudes the rest of the Kapp Hansteen succession and the Brennevinsfjorden Group it is in turn intruded by the Kontaktberget granite in which it also occurs as xenoliths. The porphyries contain metasedimentary xenoliths. No such intrusions are known in the Murchison Bay Supergroup. Quartz porphyry clasts occur in a basal conglomerate in the Murchison Bay sequence due east of Hansoya. Flood et al. (1969), following Sandford (1950) reported that quartz porphyries are distinguished by smoky coloured quartz (up to 15%) phenocrysts, often corroded, (1-3mm diam) 3-7cm -2 and with sharp contacts. Somewhat larger grey, white and pink feldspar (albite-oligoclase) phenocrysts up to 25% occur in a fine groundmass. The composition is of rhyolitic to dacitic composition and a general potash-calc-alkaline affinity. Derivation from the thick continental crust has been inferred (Gee et al. 1995). Three facies occur; massive, sheared, and folded even within one body so that their regional significance cannot readily be inferred. Ohta (1982) referred to the rocks as phyllitized rhyolite. A later schistosity penetrates all these lithologies (Flood et al. 1969, p. 61). This is consistent with the schistosity being part of the post-Hecla Hock (Caledonian) deformation and not to be confused with the pre-Kapp Hansteen Group deformation to be considered below (and p. 109). The minor upheavals associated with the magmatism would account for the local angular unconformity that follows. No great discordance is evident because of the persistence of the succession from east to west. The age of the quartz-porphyries has been estimated at 766 + 87 Ma by Rb-Sr isochron (Gorochov et al. 1977), and a revised age of 970 Ma is expected from the same authors (Ohta 1992).

103

Gerardodden Formation. The stratified volcaniclastic sequence follows with five formations as outlined by Ohta (Gee et al. 1995). Agglomerate, tuff breccia and lava formation, c. 1 km. These include units 4 to 7 (downwards) as mapped by Ohta: (4) ignimbrite; (5) andesite; (6) porphyrite; (7) tuff, breccia and agglomerate. (8) Shale formation c. 50 m This contains tuffacious laminae and is of intermittent occurrence. Tuff and tuffaceous sandstone c. 10 m. These are finely laminated tufts often graded with sandy intercalations and locally with breccias. (9) Columnar jointed porphyrite c. 10m. This massive grey rock is of rhyodacite composition and appears as a conformable lava fow. (10) Basal conglomerate formation up to 20m. These conglomerates are clast supported with monomict basal beds dominated by quartzite clasts up to 1 m in diameter and well rounded at the base but increasingly angular and polymict upwards. Because of the immense variety of volcanic facies and the fine grain of much material, chemical analysis have been used in preference to petrography to characterise the rocks. Ashes and tufts are abundant and 'many of the non fragmental rocks were interpreted as lava flows' (Flood et al. 1969).

Rijpdalen area in Central Nordaustlandet Svartrabbane Formation. Gee & Teben'kov (1996), from further mapping of the outcrops between Vestfonna and Austfonna, defined a new formation with a basic volcaniclastic content already described by Teben'kov (1983) and Ohta (1985); they are interbedded with phyllites and quartzites. Gee & Teben'kov correlated this new unit within the Kapp Hansteen Group. On mapping it was found to rest unconformably on the Helvetesflya Formation of the Brennevinsfjorden Group.

6.2.4

Brennevinsfjorden Group

The formations of the Brennevinsfjorden Group are distinguished in two main areas. To the west of Laponiahalvoya is the type outcrop on Botniahalvoya and to the east are the outcrops of Rijpfjorden and Prins Oscars Land. To qualify as a group it must be defined by its constituent formations. These are three, as yet unnamed, units in the western outcrop as listed below.

Western outcrops. The unit as described by Flood e t al. 1969, p. 53), comprises a m o n o t o n o u s sequence of interbedded quartzites, siltstones and shales. The quartzites are only rarely more than a metre thick. The bedding dipping steeply to the east in the type area mainly coincides with the cleavage. Ripple marks and crossbedding occasionally signal inversion of strata. The quartz has slight undulatory extinction. Ohta (1982 p. 7) recorded 'a 3000m thick areno-argillaceous succession'; Lauritzen & Ohta (1984) referred to 4500 m in the type area. A narrow and distinct hornfels with large idioblasts of andalusite, poikiloblastic staurolite and garnet develops within 30 m of the contacts with the porphyritic gneiss and granite. Strong cleavages with the metasediments show conformable trends with the margins of the granite-porphyritic gneiss masses. Ohta's (1982) detailed observations in Botniahalvoya are significant both in determining that the group is older and not younger than the Kapp Hansteen Group and in identifying a basal conglomerate between them. Three unnamed formations have been distinguished on Botniehalvoya by Ohta (Gee e t al. 1995): Upper sandstone shale formation Middle quartz shale formation Lower shale sandstone formation

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Rijpdalen area in Central Nordaustlandet Helvetesflya Formation (Gee & Teben'kov 1996). In this area, further mapped by Gee & Teben'kov the lower formations of the Murchison Bay Supergroup, once approximately the Austfonna Formation and now established as the Djevleflota Formation, rests unconformably on the Svartrabbane Formation, which in turn has extensive unconformable contacts with the dominantly phyllitic shale and slate Helvetesflya Formation. This has a penetrative, finegrained sericitic schistosity and a superimposed crenulation in an isoclinally folded sequence. The map suggests that the Helvetesflya and Svartrabbane formations are isoclinally folded together. The Helvetesflya Formation is in contact with extensive outcrops of granitic augen gneiss (at Ringghsdalen). This gneiss as well as the above formation is cut and/or metamorphosed by the Rijpdalen-Winsnesbreen granites which were suspected to be coeval with the Laponiahalvoya granites and confirmed as 'Grenville age' based on U-Pb zircon age data (Johansson in Gee & Teben'kov). This would suggest that the whole of the outcrops from the east would also be Proterozoic basement.

North central Nordaustlandet The Kapp Platen Formation at Kapp Platen was mapped in some detail by Winsnes (Flood et al. 1969). This unit has been variously correlated with the Austfonna rocks but in the map of Gee et al. (1995) it was shown as Brennevinsfjorden Group.

6.3 6.3.1

Subjacent metamorphic complex Evolution of ideas

Parry is credited in 1928 for classifying the granites and gneisses together as 'primitive rocks'. Nordenski61d (1863) listed seven formations from Nordaustlandet of which the lower four were (4) (3) (2) (1)

Ryss6 Formation (which he thought might be Carboniferous) Hecla Hock Formation Crystalline limestone and dolomite Gneiss with granite veins and dykes.

He sampled the lowest unit on extensive sledge journeys along the north coast of Nordaustlandet. These 'crystalline' rocks were regarded as Archean basement and were included as Urgebirge in Nathorst's synthesis (Suess 1888 and Nathorst 1910) though he expressed doubt as to the certainty of this conclusion. De Geer (1909) took the same view. A similar opinion regarding the crystalline complex of north western Spitsbergen prevailed until Holtedahl (1914, 1926), in northwest Spitsbergen,argued that the metamorphism resulted from remobilization during the Caledonian orogeny. The status of the Nordaustlandet complex was then in doubt but it differed from the northwest in having an 'unmetamorphosed stratified cover'. Sandford (1926) inclined to the view that the granites were younger. Kulling, who had access to Nordenski61d's material, in 1932 (p. 132) tabulated beneath his Kap Hansteen formation. 'Prim~irt Liggende Ok~irt' (primary layers unknown). Sandford (1950, 1956) began to suspect, and later postulated, an unconformity between the Cape Hansteen rocks and the subjacent metamorphic complex as did Orvin (1940, p. 8) 'there can be no doubt that the Barents Sea shelf forms a continuation of the Fenno-Scandinavian Archean Shields'). That connexion was later in doubt as the postulated Iapetus ocean divided the two areas (Harland & Gayer 1972); but the concept of a (Laurentian) Barents Craton was not thereby undermined. Hamilton & Sandford (1964) showed that Paleozoic thermal activity was extensive from the earliest isotopic age determinations in Svalbard. Nevertheless the dominant view was for a basement to the Proterozoic strata (e.g. Sokolov, Krasil'shchikov & Livshits

1968a) and an ancient Barents shield was postulated to bound the Hecla Hock Geosyncline to the east. We thus depend on the new series of observations by Norsk Polarinstitutt geologists mainly from helicopter reconnaissance sorties and further work by their colleagues in Sweden and Russia. Flood and Gee (Flood et al. 1969, pp. 97-120) described their sub-'Botniahalvoya' complex as of granitic gneisses and migmatites, clearly post-Botniahalvoya in age from their contrasting relationships and some metasomatism. However their description of the supracrustal inclusions therein refers to occasional extensive stratiform rocks, dominantly pelites through to quartzites, and marbles with associated amphibolites. The amphibolite facies of these inclusions contrasts with the greenschist facies of the overlying Brennevinsfjorden rocks. At that time a Caledonian event was preferred. Gee et al. (1995) mentioned that 'pre-Grenvillian basement' is suggested by U - P b data on biotite schist xenoliths within the Laponiafjellet granite. Also augen gneisses at Fonndalen in central Nordaustlandet gave a zircon age of 1048 4-27 Ma with monazite suggesting metamorphism around 960 Ma and some latest Silurian evidence of 412 Ma. Gee &Teben'kov (1996) mentioned a 'Grenvillian' age for the Rijpdalen granites (communicated by Johansson) which would seem to settle the matter. That is to say that the granites and related migmatites of central (and therefore eastern) Nordaustlandet are essentially coeval with those of western Nordaustlandet in Laponiahalvoya so that the whole complex would be Proterozoic, but rejuvenated in some degree in Paleozoic time. Whereas much of the inclusion material may be Brennevinsfjorden Group paleosome, the amphibolites, some of likely sedimentary or at least stratiform origin and others possibly intrusive, do not match the overlying rocks and so are candidates for preBotniahalvoya, i.e. pre-Brennevinsfjorden rocks.

6.3.2

Migmatic and magmatic components

In the early accounts (e.g. Sandford 1926) emphasis was given to the contrast between grey, foliated granites and gneisses, and pink granites. This sub-section concerns the former which are earlier than the late-tectonic plutons (Section 6.4). This large tract of migmatic rock has been named the Duvefjorden Complex (Teben'kov in Gramberg, Krasil'shchikov & Semevskiy 1990). There are two large outcrop areas of these migmatitic gneisses (Flood et al. 1969). In the west: most eastern Laponiahalvoya and Sjuoyane are so mapped. In the east, from Duvefjorden and eastern Rijpdalen, the whole of the eastern half of the north coast outcrops of Nordaustlandet is similarly mapped. West of Rijpfjorden Hjelle (in Flood et al. 1969, p. 103) generalized their findings as follows: Quartz monzonitic rocks with considerable amounts of supra-crustal inclusions occur and at some places with transitions into migmatic gneiss. The modal composition of the migmatite metatect does not differ from that of the average quartz monzonite. The rocks are coarse-grained, grey, hypidiomorphic to porphyritic texture, with phenocrysts of K-feldspar (often microcline and microperthite). Texture varies from slight to well foliated gneiss. Plagioclase is An20m0 and often there are Rapakivi type rims. Quartz shows undulatory extinction and accessories are biotite, muscovite, titanite, apatite, zircon and iron ores. Whereas to the south the rocks are less foliated, and show facies transitional to the Brennevinsfjorden granite, to the north (Nordkapp and Sjuoyane) gneissic structure is typical. Quartzite inclusions with up 65% quartz, epidote and some titanite obtain; mica schist inclusions comprise quartz, albite, biotite; amphibolite inclusions have quartz, oligoclase to andesine, hornblende; and almandine, calcareous inclusions have quartz, calcite, diopside, wollastonite. The gneisses often contain lenses of tourmaline-bearing muscovite. East of Rijpfjorden, Flood & Gee (in Flood et al. 1969 pp. 105-120) suggested that the exposures from Rijpfjorden through Duvefjorden and to the extreme northeast may be just the northern fringes of a large outcrop area extending beneath the ice at least to Isispynten.

NORTHERN NORDAUSTLANDET At the contacts between the low-grade Botniahalvoya Group and the granites and migmatites there is a sharp transition to biotite- and garnetbearing schists, with hornblende in the more basic facies. For example at Innvika in Duvefjorden chlorite-muscovite assemblages in Austfonna (Meyerbukta Group) rocks occurring at a distance of 500 m from the contact give way to biotite-muscovite schists. Within 100 m garnet develops with feldspathic quartz lenses in the schistosity and in the immediate contact zone are staurolite-andalusite-biotite-muscovite~zluartz assemblages in tightly folded structures in which schistosity penetrates the contact zone as well as pegmatite veins. Where the contact is with homogeneous igneous rocks there is generally cataclastic deformation. The more detailed account (p. 108) favours intrusion of granitic magma during deformation but an envelope of quartz monzonite probably solidified first at the contact. Several other such contact phenomena were described in detail (pp. 108-112). The migmatites, gneisses and syno-orogenic granites show a great variety of facies, ranging from little or no foliation or inclusions to highly foliated gneiss with abundant, often large inclusions. A typical composition is 30% quartz, 30% plagioclase, 30% K-feldspar and 10% micas with apatite and zircon. There is an overall similarity of composition throughout, modified only by the various types of inclusion. Evidence of post-magmatic strains abound from cataclastic textures, strain-shadowed quartz, and augen gneisses (augen being typically microcline).

6.3.3

Supracrustal inclusions

Flood et al. (1969, p. 61) reported that their Botniahalvoya Group 'base is not known, and no evidence of an underlying old preCaledonian basement has been found'. Nevertheless (p. 62) 'observations have confirmed a general occurrence of amphibolites east of Duvefjorden as well as within the Austfonna Formation within the migmatite border' which Flood inclined to indicate, by the abundance also of feldspathites, a possible correlation with Harkerbreen Group in N y Friesland. Whereas feldspathites (i.e. metamorphic rocks with >50% feldspar, Wallis et al. 1968, 1969) abound in all the Lower Hecla Hoek of Ny Friesland (Stubendorffbreen Supergroup) amphibolites do not characterize the Planetfjella Group which is correlated here with the Kapp Hansteen Group. They are however abundant in the underlying Harkerbreen Group of N y Friesland so that it is pertinent to enquire as to the abundance of amphibolites within the sub-'Botniahalvoya' migmatites. Amphibolites were reported as a conspicuous element in the metamorphic complex at Isispynten (Sandford 1954) associated with the grey granites (probably migmatitic) in a sedimentary series. It is noteworthy that there is no match for the gabbro-noriteanothosite of Storoya and Kvitoya (p. 17) which appear to be higher in the sequence and possibly Caledonian (Ohta 1978).

6.4

Late tectonic plutons

Two main areas of granite outcrop have been mapped. I n the west is Laponiahalvoya and in the east, Prins Oscars Land. Laponiahalvoya exposes two adjacent bodies. (1) On the west side (east of Brennevinsfjorden) is the Kontaktberget granite. This was so named by Kulling and by Gee et al. 1995. It was also referred to as the Brennevinsfjorden granite by Flood et al. (1969). Further east is the larger outcrop of the Laponiafjellet granite and migrnatite which also forms the islands to the north. There is an isolated outcrop to the southeast south of Sabinebukta mapped by Flood et al. as a subglacial extension of the Kontaktberget granite round the south of the Laponiafjellet outcrop and northeast into some small islands. This is referred to as the Sabinebukta granite. To the south and adjacent to it is a Sabineberget acid rock, probably a Kapp Hansteen quartz porphyry. (2) The eastern granites crop out in Prins Oscars Land. The main body e x t e n d s along the east coast of Rijpfjorden south of Platenhalvoya and again further south near the head of Walhenbergfjorden. There is a further outcrop to the east south of

105

Duvefjorden. These rocks were all mapped (Flood et al. 1969) as adjacent to and probably penetrating synorogenic granites and migmatites which then develop extensively to the east. Kulling (1934) first noted that the granites were not affected by Caledonian folding. Isotopic ages of the granites are the youngest in the area i.e. 400-350 (Hamilton, Harland & Miller 1962; Krasil'shchikov 1965, Winsnes 1965). However, later isotopic work (Gee et al. 1995) requires a radical reapraisal. Hjelle (Flood et al. 1969, pp. 121-128) described the two postorogenic granites': Brennevinsfjorden in the west and Rijpfjorden in the east. The most frequently observed mineral association is quartz-microcline-plagioclase (albite-oligoclase)-biotite-muscovite. Nordaustlandet granites are more alkaline, less calcic and femic than analogous granites in N y Friesland and Northwest Spitsbergen. This is not surprising with the new evidence that they were not coeval.

6.4.1

Laponiahalvoya granites (Hjelle in Flood et al. 1969; Gee, Johansson, Ohta et al. 1995)

The Kontaktberget granite outcrop, if continued beneath fjord and ice cover, appears as an arc with the Botniahalvoya outcrop on the outside (W and S) and the Laponiafjellet foliated granite and migmatic complex on the inside to the east and north so disposed as a broad antiform plunging to the south. The Kontaktberget granite is light grey to red, medium grained, part porphyric, somewhat foliated and cataclastic. Quartz (30-35%) exhibits undulatory extinction bluish with brittle deformation; K-feldspar (30-35%) occurs mostly in medium grained ground mass but also as phenocrysts up to 3 cm long. It is often perthitic and with microcline twinning. Plagioclase (0-20%) is often sericitized with An from 5 to 15%. Biotite (10%) and muscovite (5%) occur with tourmaline, fluorite, ilmenite, zircon and apatite. Intrusive contacts are observed with Kapp Hansteen Group strata exibiting fine-grained marginal facies. Such relationships seen to the east at Sabineberget contradict Sandford's (1950) unconformity interpretation based on air photographs. Anomalous compositions by assimilation of micaceous and calcareous metasediments occur. An occasional orbicular facies is rich in tourmaline. The Laponiafjellet granite is a coarse porphyrite variety, almost an augen gneiss. The foliation and shearing as seen against the quartzmonzonite of the migmatic complex is related to the final stages of the emplacement orogeny rather than as flow during intrusion. The granites are thus late rather than post-orogenic. The composition is quartz 25-30%, Kfeldspar 25-30%, plagioclase 20-25%, and micas 10-15% and accessory minerals parallel those in the Kontaktberget granite. Whereas the Kontaktberget granite has distinct xenoliths near the margin, the Laponiafjellet granite with larger xenoliths merges into migmatite complex with large paleosome rafts both pelitic and psammitic, and occasional marble. Chemical composition of both granites suggests an origin from melting of upper crustal rocks. The Nordkapp granite. The northernmost island of Svalbard, north of Nordaustlandet was sampled by Hjelle (1966) who classified it with the second of his divisions (i.e. with the late tectonic plutons described above and distinct from those that follow. The structural relationship has not been determined. There is one record of isotopic age. Hamilton & Sandford (1964) by Rb-Sr on feldspar obtained 537 Ma. This leaves the age of the intrusion open. However, by analogy with related granites in Nordaustlandet an early Neoproterozoic origin seems probable with later reheating.

Isotopic ages.

Isotopic ages (recalculated) were by Krasil'shchikov

et al. (1964) K - A r on biotite 388 and 393 M a and on whole rock 413 and 428 M a from the southwestern outcrop and by Gayer et al.

(1966) K - A r on biotite 390-399 M a and on muscovite 443 Ma. On the time scale adopted for this work the biotite ages are Early to Middle Devonian and thus the shearing phase could be Late Devonian (i.e. Svalbardian). However, Johansson & Balashov (in Gee et al. 1995) reported zircon ages in the Kontaktberget granite of 939 + 8 and of the Laponiafjellet granite of 961 4- 17 Ma. This is consistent with the contact evidence that the Laponiafjellet

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rock was earlier than the Kontaktberget granite, but the difference between the apparent ages may not be significant. The implications of these results are far-reaching, if the zircons crystallised with the granites and are not inherited. Because all the other ages are Silurian-Devonian, which would then indicate a major Paleozoic regional thermal event to reset all but the zircon crystals and some R b - S r ratios. If this be the case it calls into question the whole area of granites and migmatites to the east where already several values around 600Ma indicated some Precambrian event in addition to the ubiquitous Silurian early Devonian thermal activity.

6.4.2

The pink or red rock is of normal granitic composition with hypidiomorphic, medium-grained and often shear structures. Post-magmatic strain is evident from the undulatory extinction of quartz. Muscovite exceeds biotite and accessories include iron hydroxides and fluorite. Feldspar margins and fissures are embayed by quartz. The K-feldspar is typically microcline-microperthite, the plagioclase is Ans_~0. Biotite content increases near contacts and xenoliths as does more calcic palgioclase. Intrusive sharp contacts with supracrustal rocks are common, but may be transitional with some migmatites. Xenolith distribution gives the impression of an unroofed batholith. Moreover, the pink granite also intrudes homogeneous grey augen-gneiss approximating to quartz diorite, as do apophyses of aplite and pegmatite. A typical sequence is: (a) supracrustal relicts, (b) synorogenic quartz monzonitic gneisses, (c) late-orogenic Rijpfjorden granite, (d) aplite and pegrnatite dykes. The dykes are occasionally foliated and thus are also late-tectonic. K - A r isotopic determinations by Krasilshchikov et al. 1964 (recalculated) on whole rock gave 362, 362, 347, 352, and 438 Ma, on muscovite 387Ma; and on biotite 377Ma. These are all Silurian-Devonian ages and again suggest final Devonian stability. On the other hand Gee & Teben'kov (1996) reported a 'Grenvillian' age in zircon by Johanssen from the Rijpdalen granite. No zircon determinations are available.

6.5.1

Minor igneous bodies Acid intrusions

The granitic, aplitic and pegmatitic dykes belong to the Late tectonic granitic episode treated above.

6.5.2

6.5.3

Dolerite sills and dykes

Relatively unaltered dolerite dykes and sills abound especially in western Nordaustlandet and Hinlopenstretet. They are most probably part of the Cretaceous igneous episode which was extensive throughout most of eastern Svalbard. They can best be dated where related to lavas in K o n g Karls Land to the south and are discussed in Chapter 5.

The Rijpfjorden, Rijpdalen and Duvefjorden granites

Outcrops of this facies are more complex, extending in a N - S strip from the east of Rijpfjorden south through Rijpdalen and with outliers east of Wahlenbergfjorden and south of Duvefjorden. Contacts are with both Botniahalvoya and younger Meyerbukta formations and with the large eastern migmatite complex (Hjelle in Flood et al. 1969).

6.5

determinations. If they are the product of island arc magmatism of Neoproterozoic or Paleozoic age the Barents Craton concept as including the Duvefjorden Complex is challenged.

Basic layers to northeast

In the northeasternmost corner of this study area (Nordmarka, Storoya and Kvitoya) occur basic igneous complexes which are not matched elsewhere in Svalbard (Hjelle, Ohta & Winsnes 1978, Ohta 1978). Basic stratiform rocks appear to be higher in the sequence than the relatively flat-lying migmatic gneisses. Moreover, structurally and petrographically the basic rocks appear to be syntectonic (with the migmatites). Their calc-alkalic and tholeiitic compositions suggested thick continental terranes that would be consistent with a Caledonian foreland to the east. Ohta (1978) in particular described the detailed mineralogy and geochemistry of the Storoya gabbro-diorite complex. Whether the strata were formed as flows or sills near the surface or as part of 'an island arc setting with a thick continental crust' as Ohta suggested is an open question. He argued for a Caledonian origin in 1978 a view that might be modified in the light of later extensive Proterozoic age

6.6

Summary of isotopic ages

All numerical values in this list are in Ma. Analytical details with estimated errors etc. must be obtained from the original papers. Such early data were abstracted up to that time by Gayer et al. 1966. The values given here have been recalculated as necessary according to 1976 constants. They are plotted on the map (Fig. 6.4) on which the following numbers give the references. (1) Hamilton & Sandford (1964) by Rb-Sr at Oxford: from biotite in gneiss at Isispynten 358, 411, 415; from 'Southern Land' muscovite in granite and aphite 373, 378; from Nordkapp feldspar in granite pegmatite 537; from Rijpdalen schist, biotite 618, muscovite 636, whole rock 581. (2) Krasil'shchikov, Krylov & Aljapysev (1964) by K-At at Vinbukta on the E coast of Rijpfjorden, whole rock grey granite 362, pink granite 362, porphyritic granite 347, granosyenite 352, muscovite in pegmatite 388; Rijpfjorden (Wordiebukta) biotite in biotite gneiss 438; from E coast of Brennevinsfjorden (Zeipelbukta) rapakivi granite whole rock 413, rapakivi granite biotite 388; medium granite biotite 393; granite in coastal gravel whole rock 428. (3) Gayer, Gee, Harland, Miller, Spall, Wallis & Winsnes (1966) compiled previous Svalbard determinations including the above with some analytical data etc., converting Russian to western constants and in addition reported from Nordaustlandet material collected by Winsnes determined by K-Ar from north Laponiahalwya west Beverlysundet on musconvite from granite pegmatite 443; from altered biotites in unfoliated pink granite 399; from head of Wahlenbergfjorden on muscovite from foliated granite 420. (4) Krasil'shchikov (1970) also from head of Wahlenbergfjorden by K-Ar whole rock 376. (5) Edwards & Taylor (1976) from a large granite boulder in the Vendian tillite at Aldousbreen north of Wahlenbergfjorden obtained 1275. (6) Gorochov, Krasil'shchikov, Mel'nikov & Varsavskaja (1977) Reported a whole rc-:k Rb-Sr age of 766 from (probable Kapp Hansteen volcanics in) Botniehalv~ya. Because of the high initial strontium content this was later revised to 970 (see Ohta 1992 and Gee et al. 1995). (7) Ohta (1982) reported a whole rock Rb-Sr determinations in the lower Murchison Bay Supergroup of 520. (8) Lauritzen & Ohta (1984) reported Rb-Sr determination on whole rock from Nordre Repoya of c. 600. (9) Ohta (1992): compiled previous Svalbard data making corrections for 1976 constants as necessary. In addition he reported a whole rock Storoya age by K-Ar of c. 600 and gave a revised age of 970 from the original 786 whole-rock Rb-Sr determination from the ?Kapp Hansteen acid rocks of Botniahalvoya. (10) Gee, Johansson, Ohta, Tebenkov, Krasil'shchikov, Balashov, Larionov, Gannibal & Ryungenen (1995) gave details of new U-Pb and Pb-Pb determinations of zircons, by laboratories in Stockholm and Apatity, with selected ages of the Kontaktberget granite 939+8 and of the Laponiafjellet granite 961-4-17 which in view of uncertainties were taken as c. 950. Also noted were tentative ages by Larionov from migmatite rafts in NE Laponiahalvoya by Pb-Pb indicating a pelitic paleosome at c.1600 and also tentative zircon results from the Brennevinsfjorden Group at c. 1500. (11) Krasil'shchikov, Kuno & Sirsova (1996) reported earlier unpublished age determinations on metagabbros from Storoya c. 677 Ma and for Kapp Laura, 442 Ma. (12) Gee & Teben'kov (1996) reported, without details, on 'Grenvillian' age of the granites of southern Rijpdalen based on U-Pb zircon determinations and plotted on their maps the value 1050Ma.

NORTHERN NORDAUSTLANDET

107

Fig. 6.4. Summary of isotopic ages from Nordaustlandet. Outcrops mainly from Gee et al. (1995), and Gee & Teben'kov (1996). Sources of data indicated by numbers in parentheses are as follows: (1) Hamilton & Sandford (1964); (2) Krasil'shchikov, Krylov & Alpapyshev (1964); (3) Gayer et al. (1966); (4) Krasil'shchikov (1970); (5) Edwards & Taylor (1976); (6) Gorochov et al. (1977); (7) Ohta (1982); (8) Lauritzen & Ohta (1984); (9) Ohta (1992); (10) Gee et al. (1995); (11) Krasil'shchikov et al. (1996); (12) Gee & Teben'kov (1996).

6.7

Structure of Nordaustlandet

From the structural reconnaissance reported by Gee (Flood et al. 1969) it seemed that an igneous-migmatic contact rather than

Earliest maps typically show the few rock types recorded to be separated by faults. The first detailed structural traverse was recorded by Kulling (1934) in which the Murchison Bay strata were steeply f o l d e d - mainly upright but with an eastward-verging recumbent fold rooted at Floraberget. Subsequent work by Ohta (1982) showed that the repetition of strata required for KuUing's isoclinal interpretation was indeed better explained by the downward succession into similar but still older strata. Therefore the easterly vergence cannot be sustained. Sandford (1956), using Kulling's data and interpreting from air-photographs plus his own and other available observations, published the first structural map of northwestern Nordaustlandet (Fig. 6.5). It makes little structural difference whether the sub-jacent complex was formed earlier or later than the Hecla Hoek sequence. Sandford mapped a nearly straight N-S shear zone just west of D u v e f j o r d e n - his 'Dove Bay Fault'. He noted that no Hecla Hoek strata are known east of it. It could certainly fit later hypotheses of strike-slip displacement. It would also be consistent with the evidence ofpost-pluton shear in the granites. However, Gee (in Flood et al. 1969) did not observe any post-migmatite displacement there. There are minor shear zones in which porphyritic granite has developed into augen-gneiss. From further fieldwork Gee et al. (1995) seeking evidence i.a. for terrane boundaries did not report any other major shear zone in Nordaustlandet. Such a Duvefjorden Fault was mapped east of Duvefjorden, trending N N W SSE, by Krasil'shchikov (1973) east of which he mapped a pre-Riphean basement, later referred to as the Duvefjorden Complex. However, Krasil'shchikov et al. (1996) marked only a N-S anticline just east of Duvefjorden within the North East uplift (Fig. 3.10).

an unconformity separates the subjacent complex from the supracrustal strata. However, from the discovery that the westerly granite plutons, at least, yielded early Neoproterozoic zircons a new model appears to emerge (Gee et al. 1995). A Proterozoic migmatic-magmatic invasion of metasediments was somehow subsequently altered thermally so that K - A r and R b - S r ages therein appear to be midPaleozoic. This somewhat enigmatic result, albeit with work still in progress, is addressed in Section 6.8 below. Three east-west sections (Flood et al. 1969, p. 68) show mainly open upright folds without great amplitude so that coeval strata have wide distribution. Many faults plotted on a map (p. 94) were shown as vertical. The faults and fold axes are generally N S or N N W - S S E and are interpreted as strike-slip both dextral and sinistral. The migmatic-magmatic (crystalline) areas tend to be positive and determine the main fold structure which is of broad anticlines plunging south with the youngest strata to the west and south. Gee's syntheses noted that the Nordaustlandet structure is dominated by a Caledonian (post-Canadian/pre-Pridoli) fold system. The cleavage, dipping steeply eastwards, is axial planar to the folds which are asymmetric towards the west i.e. as in Ny Friesland and verging westwards. The Hinlopenstretet synclinorium gives the strata on both sides a similar sequence with the oldest rocks away from it. One group of faults is related to the E - W compression of the Caledonian folding with srike-slip displacement dextrally on W S W - E N E trends and sinistrally on W N W - E S E trends. The youngest strata, the Sparreneset formation, dip steeply west into Hinlopenstretet at both Sparreneset and west of Krossoya. The oldest strata appear east of Lady Franklinfjorden on the western flank of the Vestfonna antiform which plunges south beneath

108

CHAPTER 6

Fig. 6.5. Outline geological map of Nordaustlandet and adjacent areas of Ny Friesland illustrating the major structural featues, mainly from Gee (in Flood et al. 1969). Vestfonna. In its core to the north is the Laponiahalvoya intrusion. Not enough is known of the structure further east. It is possible that an analogous synform could occupy Nordenski61dbukta. Then further east there is the option to continue the gentle fold pattern with a Kapp Platen antiform or to treat that as the western edge of the Duvefjorden Complex-Barents Craton (Fig. 6.5). Other dominantly strike-slip faults trend NNW-SSE and N N E SSW. Carboniferous strata are not thereby displaced so that they may have formed during the Late Devonian Svalbardian movements. The Murchison Bay Supergroup strata were undeformed prior to the Caledonian folding. Gee's (1969) discussion of the relationship with the Botniahalvoya rocks was overtaken by the 1982-1984 stratigraphy already recounted so that there must be an unconformity beneath in the Murchison Bay Supergroup and another break beneath the Kapp Hansteen Group. The E-W sections south of Kapp Platen sketched by Winsnes (Flood et al. 1969, p. 66), show an open (upright) fold structure without sensible vergence and apparently cut by the Rijpfjorden granite. Assuming that the latter is early Neoproterozoic then the folding might be part of the tectonism represented by the Botniahalvoya unconformity. This might confirm the correlation of the Kapp Platen strata within the Brennevinsfjorden Group. Correlation with Ny Friesland is suggested in the Chapter 7 and discussed in Chapters 12, 13 and 14.

6.7.1

A Barents Craton

Throughout the fluctuating interpretations of the role played by Phanerozoic diastrophism in Nordaustlandet, there has been a

persistent opinion that the Duvefjorden Complex could be part of a Precambrian shield. This could be confirmed by further isotopic investigations in eastern Nordaustlandet. If it be so then Barentsia would not be part of Baltica but rather an extension of Laurentia and separated by the ensialic Hecla Hoek aulacogen from the East Greenland part of Laurentia (as discussed further in Chapter 12).

6.8

The Lomonosov Ridge in relation to Nordaustlandet

Little is known of the Lomonosov Ridge except that it is a markedly linear, non-magnetic submarine feature now bordering the Eurasian Ocean basin. This basin opened by Cenozoic spreading along the mid-oceanic Nansen Gakkel Ridge as the northerly terminus of the De Geer transform separating Svalbard from Greenland. The pre-Cenozoic configuration is constrained by simply closing the Eurasian and the Greenland and Norwegian basins. This brings the Lomonosov Ridge adjacent to the northern coasts of Svalbard and perpendicular to the widespread Caledonian grain of Svalbard. From its positive morphology and non-magnetic nature the Ridge would appear to be of continental rather than of oceanic affinity. Indeed such a relict 'orogen' could have focused the Cenozoic thermal fission, so determining the initial location of the NansenGakkel Ridge. That might be as far as speculation should be taken; but it may be worth considering this situation in relation to Nordaustlandet and to the mid-Paleozoic strike-slip model developed in this work. That model (e.g. Harland 1966, 1969) postulated the origin of the Lomonosov Ridge as a compressional feature that formed across the front of the eastern terranes of Svalbard as they progressed from the East Greenland province by strike-slip to

NORTHERN NORDAUSTLANDET their Carboniferous-Cretaceous location north of Greenland and Canada and so adjacent to where the Lomonosov Ridge is now. That northward progression could have been accomplished by the continental foreland of Svalbard's eastern province overriding the intervening Thalassic ocean. The subducted ocean floor would have sunk i.a. beneath northern Nordaustlandet and the ridge would develop from the scrapings of the ocean floor sediments. The above speculation is entered because the later phases of this translation would be Devonian and the later thermal rejuvenation along the E-W northern margin of Nordaustlandet from early radiometric determinations tend to be Devonian.

(3)

(4) (5)

(6)

Conclusion

(7) (8)

A model is suggested for further criticism and testing in which the following events in Nordaustlandet would be accommodated.

(9)

(1) (2)

Early to mid-Proterozoic sedimentation to form the Brennevinsfjorden Group. Early Neoproterozoic migmatism/magmatism (Grenvillian) Kapp Hansteen volcanics and Laponiahalvoya granites.

109

Later Neoproterozoic through Early Paleozoic sedimentation of the relatively unaltered Murchison Bay and Hinlopenstretet supergroups. Silurian (Ny Friesland) orogenic folding in NS axes with EW compression to transpression. Later Silurian through Devonian northward migration of Svalbard with subduction around North Greenland towards Ellesmere Island. Late Devonian accumulated thermal effects of subduction with Lomonosov orogen transverse to progression and hot fluids or magma from buried slab rejuvenating the E-W zone of Early Neoproterozoic granites etc. Late Paleozoic denudation and sedimentary cover. Renewed uplift in Late Cretaceous Cenozoic time as heat accumulated beneath northern Nordaustlandet and the Lomonosov Ridge leading to Spreading of the Eurasian Ocean Basin with the thermal tilting of the pre-Carboniferous basement so that northern Nordaustlandet exposes the deeper roots of the earlier structures whereas Late Paleozoic and Mesozoic platform strata obscure the basement further south.

Chapter 7 Northeastern Spitsbergen W. B R I A N 7.1 7.2 7.2.1 7.2.2 7.2.3 7.3 7.4 7.4.1 7.4.2 7.4.3 7.4.4 7.5 7.6 7.6.1 7.6.2 7.7 7.7.1 7.7.2

Geological frame, 110 Younger (cover) rocks, 112 Cenozoic lava, 112 Mesozoic dolerites, 112 Triassic to Carboniferous Strata, 112 Post-Permian deformation, 112 Ny Friesland plutons, 112 The Chydenius (breen) Batholith, 113 The Lomonosovfonna pluton, 113 Origin of magnos, 113 Lamprophyre dykes, 113 The Hecla Hoek Complex: the continuing debate, 113 Hinlopenstretet Supergroup, 116 Oslobreen Group, 116 Polarisbreen Group, 117 Lomfjorden Supergroup, 118 Akademikerbreen Group, 119 Veteranen Group, 119

The land (area) considered here is bounded on the west by Wijdefjorden and on the east by Hinlopenstretet and Storfjorden. The southern boundary is somewhat indefinite. For descriptive convenience Carboniferous through Triassic stratigraphy is treated in Chapters 4 and 5 and Devonian strata to the northwest in Chapter 8. It makes geological sense for these chapter areas to overlap where they meet. Ny Friesland was the name for most of the area under consideration. However, after the accession of the Norwegian King Olav V in 1957 his name was given to what had previously been a somewhat indefinite territory, mostly ice covered (the Terre Glac6e Russe of some older maps) to the south east of Ny Friesland. Olav V Land was defined to take in some of what had been referred to as Ny Friesland and early accounts should be read with this in mind (Miloslavskiy et al. 1993, map D8G). This chapter thus concerns Ny Friesland and north western Olav V Land and for descriptive economy Ny Friesland will be used for the area where most of the older rocks crop out. Much of the interior is covered by highland ice rather than an ice cap, meaning that the ice is not thick enough for the surface to be independent of the underlying relief. Indeed the ice cover is broken here and there by rocky cliffs of submerged valley glaciers. The three largest areas of continuous ice are Lomonosovfonna, Asg~rdfonna and Valhallfonna. The inland ice flows out along valley glaciers, often to the sea. In Olav V land the second largest glacier in Svalbard, Negribreen, meets the sea in a continuous ice cliff (Fig. 7.1). In addition there are independent valley and corrie glaciers. The two highest mountains in Svalbard (Newtontoppen 1717 m, and Perriertoppen 1712 m), each typically supporting a small ice cap, are not conspicuous in this highest mountainous region. An advantage of the area for geologists is the admirably clear rock surfaces in cliffs and glaciated pavements. When the Cambridge group began a systematic investigation of the geology of Ny Friesland there was no topographic base for most of the interior. Thus a combined survey was necessary in which the position of geological features was fixed by triangulation, thus producing a topographic map at the same time. The contours were plotted by a simple photogrammetric plotting table made for the purpose in Cambridge (Harland & Masson-Smith 1962). The main focus of Cambridge research until about 1965 concerned Ny Friesland, hence the balance of this Chapter may seem one-sided. The early work of Blomstrand (1864), Nathorst (1910), Tyrrell (1922), Odell (1927), Fairbairn (1933), Kulling (1934) and Fleming & Edmonds (1941) formed the basis of these investigations.

HARLAND 7.8 7.8.1 7.8.2 7.8.3 7.9 7.9.1 7.9.2 7.9.3 7.10

7.10.1 7.10.2 7.10.3 7.10.4 7.10.5 7.10.6

7.1

Stubendorffbreen Supergroup: succession, 121 Planetfjella Group, 121 Harkerbreen Group, 122 Finnlandveggen Group, 124 Stubendorffbreen Supergronp: genesis, 125 Petrology, 125 Geochemistry, 126 Isotopic ages, 127 The Hecla Hock Complex: mid-Paleozoic structure and metamorphism, 128 Fold and nappe structure, 128 Fabric and shear zones in the Stubendorffbreen Supergroup, 129 The Billefjorden Fault Zone, 129 Planett~ella schists, 129 Kinematic interpretation of transpressive shear in the Stubendorffbreen Supergroup, 130 Metamorphism, 131

Geological frame

The rocks divide naturally into three: older, younger and 'drift'. The older rocks comprise the Hecla Hoek complex and later batholiths. Unconformably overlying this are the cover strata: the northern extension of the Spitsbergen Basin sequence, being mainly Carboniferous and Permian with conformable softer Triassic rocks above. The youngest rocks are Q u a t e r n a r y - generally Late Quaternary glacial and marine beach deposits of trivial bulk. These three units are separated by two or three surfaces. (1) The older surface is the obvious unconformity which oversteps most of the older rocks. It is continuous in the south where it dips to sea level but occurs in Ny Friesland with small Carboniferous and Permian outliers. Indeed this is an unconformity with both overstep and some overlap. Originally a peneplane, it now emerges, with a southerly dip, from beneath the Central Basin and Eastern Platform to rise with an arched surface: enveloping the summits of the high mountains formed of the older rocks. Indeed Ny Friesland mounts the highest peaks in Svalbard. Towards the margins outliers of Carboniferous strata are perched on the flat unconformity at the mountain tops. More often the flat top is covered by ice or snow. Elsewhere the summits of sharp peaks fall within, or define, the smooth projected unconformity surface. (2) The younger surface is not so obvious because in the higher ground it is postulated to coincide with the older one, i.e. as an exhumed peneplane, or to truncate and cut down into it. It is indeed the present summit height envelope which encompasses all mountain tops whether of older or younger rocks. In this area it is demonstrably post-Triassic; further south it is at least post-Eocene. This is the surface that gives Svalbard a flat-topped appearance when seen from a distance and when the sharp peaks and steep cliffs are not evident. It represents the Late Cenozoic erosion surface that i.a. truncates the West Spitsbergen (Paleogene) Orogen. (3) The youngest surface is the most conspicuous being of latest Neogene or Quaternary dissection of the younger surface and is being actively formed today. It is the surface on which the youngest Quaternary deposits and glaciers rest so giving rise to the present day topography. Each of these surfaces represents a major diastrophic and erosional event. The older surface marks the Ny Friesland (Caledonian) Orogeny and its reduction to a peneplane. The younger surface marks the West Spitsbergen Orogeny and related tectogenesis in this area and its reduction again to a peneplane.

N O R T H E A S T E R N SPITSBERGEN

111

Fig. 7.1. Topographic and place name map of Ny Friesland. Based on Harland & Masson-Smith (1962). Spitsbergen, southern Ny Friesland 1 125 000, Royal Geographical Society and Geological Map of Svalbard 1:5000 000, sheet 3, Norsk Polarinstitutt.

112

CHAPTER 7

The youngest surface marks the relative uplift of that peneplane, in relation to sea level and its dissection to the distinctive relief seen today. The rock units are bounded by faults as well as by unconformities. Faults which displace the relatively flat-lying younger rocks are easy to map. They are demonstrably postPermian and probably belong to the Paleogene diastrophism as the eastern response of the West Spitsbergen Orogeny. Most faults within the older rocks did not continue to be active beyond the N y Friesland Orogeny. However, the Billefjorden Fault Zone (BFZ) was active in Paleozoic and Mesozoic as well as Cenozoic time. It bounds the Hecla Hoek rocks, faulting them against (Devonian) Old Red Sandstone to the west which is lacking in this sector and will be treated in the northwest sector (Chapter 8). The Lomfjorden Fault Zone is demonstrably post-Carboniferous; its earlier history is uncertain. It was certainly active during the Paleogene West Spitsbergen Orogeny. The main part of this chapter concerns the older rocks, i.e. the Hecla Hoek complex with its related intrusions (mainly the large late tectonic granite plutons). However, in conformity with this systematic descriptive approach the rocks are treated from the top down and the story interpreted from oldest to youngest follows in Part 3. This has the advantage of leaving the most difficult problems concerning the possibility and identity of a more ancient basement within the Hecla Hoek Complex till last. The youngest (Quaternary) rocks will not be treated here because there is little to distinguish their nature between the different sectors of Svalbard. Any generalizations belong to Chapters 21 and 22. The older rocks to the northeast pass without significant disconformity across Hinlopenstretet into the Hecla Hoek sequence of Nordaustlandet.

7.2

7.2.3

Sassendalen Group, 316 m (Mid- and Early Triassic). The Sassendalen Group strata mainly, shales and silstones, are as usual less resistent than the underlying Kapp Starostin Formation. The outcrop probably accounts for much of the low-lying ice covered area of Olav V Land and is discussed in Section 5.4. It is best known where it emerges southeast of Sassenfjorden in the type Sassendalen area as described in Chapter 4.4. The rocks are peripheral to the area considered in this chapter. The underlying three groups are also detailed mainly in Chapters 4 and 17 and the eastern outcrops in Chapter 5. Tempelfjorden Group, 381m (Late Permian). In many areas of Svalbard the Kapp Starostin Formation, a siliciclastic to cherty unit is a resistent marker of relatively uniform facies. Gipsdalen Group, 828+m (Early Permian and Pennsylvanian). The Gipsdalen Group of five formations is mainly formed of carbonates and evaporites. Facies vary markedly and are thicker in the Billefjorden Trough. The upper units extend westwards across the Billefjorden Fault Zone (BFZ) on the Nordfjorden High. The lower units thicken to the abrupt margin of the Fault Zone. It is noteworthy that the western margin of the older rocks of the Ny Friesland orogenic structure is also formed by the BFZ which continued active and controlled the western margin of the Carboniferous Billefjorden Trough. Billefjorden Group, 316m (Mississippian). The Billefjorden Group consists of two formations in the Billefjorden Trough. They are largely of continental sandstones with plant beds and some coal. Whereas these strata form the base of the cover or platform succession of the Central Basin (Chapter 4) they are preserved in a series of down-faulted outliers far to the north in western Ny Friesland just east of the BFZ. They may well have covered much of the older surface of western Ny Friesland before erosion. Differences are most evident in the lowest strata of the Billefjorden Group as seen in the map and section (from Cutbill, Henderson & Wright in Harland, Pickton & Wright 1976).

Younger (cover) rocks 7.3

7.2.1

Post-Permian deformation

Cenozoic lava

Teben'kov & Sirotkin (1990) reported the presence of a single small nunatak at the head of Manbreen, on the south side of Valhallfonna in eastern Ny Friesland, that consists of lava overlying Precambrian schists of the Planetfjella Group. The nunatak is only 10-30m high and is at an altitude of 800-820 m. The lower contact of the lava with the schist is subhorizontal. The lava is flaggy with subhorizontal joints and little internal structure; it was interpreted as a single lava flow. The lava is partly vesicular and scoriaceous, especially at the top, and contains phenocrysts, mainly of olivine, but also plagioclase and minor clinopyroxene. By analogy with the Woodfjorden plateau lavas, a mid-Miocene age was suggested, and it may once have covered the whole area. At the same time they rejected correlation with either the Mesozoic dolerites or the Quaternary trachy basalts from Bockfjorden. A non-oceanic magmatic source common with the Miocene lavas with TiO2-KzO-P202 ratios respectively 52.6-54.5%; 37.0 38.6%; 8.3 8.8%.

7.2.2

Triassic to Carboniferous strata

Mesozoic dolerite

A dolerite outcrop beneath the ice cap at Bivrastfonna, west of southern Lomfjorden, was included in the survey of dolerites by Tyrrell & Sandford (1993) and was mapped in more detail by Cutbill (1968) who showed it resting on sandstones of the Billefjorden Group. The ice cap is on a flat-topped mountain of truncated Veteranen Group Hecla Hoek strata and the dolerite is presumed intrusive into the overlying Carboniferous sandstones the upper contact of which is obscured if not removed by the ice. It must now be presumed to belong to the extensive Early Cretaceous magmatic event evident in many other outcrops east of Lomfjorden where black sills in Carboniferous and Permian strata are conspicuous in cliff sections.

The N-S Balliolbreen Fault is the main fault of the BFZ and it is seen best in the cliff north of Alandvatnet where a preCarboniferous reverse high-angle fault juxtaposes Old Red Sandstone on the footwall and metamorphic rocks of the Hecla Hoek complex on the hanging wall. This key exposure, first noted by Vogt in 1923 and later investigated by McWhae (1953) and by Harland in 1953 (1959), has been the subject of detailed structural mapping by Lamar, Reed & Douglass (1986) and Lamar & Douglass (1995). But as their area was predominantly of the Old Red Sandstone rocks, discussion of their work fits better into the following chapter in which the Billefjorden Fault Zone must be addressed from another point of view. In southwest Bfinsow Land not only are the strata folded in a compressive sense, but the upper gypsiferous strata are deformed penetratively so that original anhydrite 'spheres' have been sheared into westward-dipping elongated ellipsoids. The other main N - S fault that cuts the younger rocks is the Lomfjorden Fault, with its associated splays. This is perhaps the most conspicuous fault in the map of Ny Friesland though not so active as the BFZ in pre-Carboniferous time. It also concentrated Paleogene reworking of Mesozoic strata. The two fault zones are associated with normal dip-slip faults which, striking with the older structures, are only evident where the cover rocks are present.

7.4

Ny Friesland plutons

Pre-Carboniferous acid plutons intrude deformed Hecla Hoek strata. The boundaries are generally concealed beneath ice and Carboniferous cover, and so are mainly conjecture on the map except where the thermal aureole can be mapped. Three plutons have been identified, possibly the northern two are connected at depth.

NORTHEASTERN SPITSBERGEN

7.4.1

The Chydenius(breen) Batholith (Odell 1927; Harland 1959; Teben'kov et al. 1996)

This is the largest outcrop and is fairly well delineated by a thermal aureole superimposed on the regional metamorphic zones where the rocks are exposed. It forms the body of the highest mountain, Newtontoppen, which is mostly ice covered. The rock is a porphyritic granite with large rectangular pink orthoclase phenocrysts (not unlike Shap granite of England). The mineral composition from 40 samples ranged from adamellite to granodiorite (Harland 1959). This is typical of late tectonic plutons without noticeable foliation. Where marginal facies can be seen xenoliths and hybrid facies are evidence of stoping. The typical light-coloured coarser facies gave quartz 17%; potash feldspar (mostly microcline, often perthitic; the large phenocysts are typically orthoclase) 25%; plagioclase (oligoclase where determined) 11%; hornblende and occasional augite with associated chlorite 7%; titanite 0.6%; apatite 0.2%; zircon, allanite, muscovite, pyrite and ilmenite total about 0.25% (Harland 1959). It was from this pluton that early K Ar age determinations were made of a few samples, a small exposure on the flank of Newtontoppen at Eplet (Newton's apple). The values recorded by Gayer et al. (1966) are 385, 4 0 1 + 8 , 4024-8, 388+14; 406+15. Early to Mid-Devonian ages are suggested. A minor pluton occurs at Raudberget to the north of lower Chydeniusbreen and may have a subterranean connexion with the Newtontoppen granites. Teben'kov et al. (1996) in a historical introduction to their investigation omitted to mention the above work from the Cambridge reconnaissance which mapped and named most of the area topographically and geologically, the granite outcrops being virtually the same as the more detailed 1996map. They did, however, suggest a change in name to the 'Chydeniusbreen granitoid suite' to conform to the Norwegian Stratigraphic Committee and against the principal of priority and that names should be proposed according to official maps at the time. However, Teben'kov et al. described a more detailed survey of the individual outcrops, their structural features, with petrological and geochemical data. They described the following rock types: 1, melanosomes and dark grey granosyenites; 2, pink-grey granosyenite and pink quartz monzonite; 3, grey granite; 4, granosyenite with aligned K-feldspar phenocrysts; 5, aplitic veins; 6, pegmatites; 7, quartz-feldspar porhyry; 8, lamprophyre, their sequence of emplacement in that order. They concluded that the Newtontoppen granitoids are mainly granite and granosyenite intermediate between alkali-calcic and alkalic as between S and I-type granites. New Rb-Sr age determinations (Teben'kov et al. 1996) by whole-rock apatite isochron method gave 432 + 10 i.e. 30million years older than the earlier K - A r values which they interpreted as a cooling age. An Early Silurian age might challenge the Gee & Page (1994) Early to mid-Silurian age for the main metamorphism to the west, the granites being clearly intruded into already deformed strata as a batholith. Unfortunately the successive intrusive phases were not distinguished isotopically, and the innermost ?latest grey granites may not have been dated.

7.4.2

The Lomonosovfonna pluton

This is exposed only in the upper reaches of Nordenski61dbreen at Terrierfjellet, Ferrierfjellet and Ekkoknausane, but is projected to cover a large area beneath the ice field and so may qualify as a batholith. Evidence for its eastern subglacial extent is seen in granite boulders in the moraines of Tunabreen and Von Postbreen at the head of Sassenfjorden. From morainic specimens in Nordenski61dbreen, Tyrrell (1922) described pegmatites, quartz, veins and a syenitic suite. The syenite was confirmed in situ (Harland 1959). An unfoliated granite boulder from the moraine of Tunabreen at the head of Tempelfjorden yielded a Rb-Sr ?Late Silurian age of 421 + 11 (Gayer et al. 1966). Its most likely source

113

would be from a subglacial outcrop of the eastern extension beneath Lomonosovfonna of the Nordenski61dbreen Batholith. Teben'kov et al. (1996), without further work or reference to Tyrrell, referred to this as the Ekkoknausane group of small intrusives, more likely into the root of the batholith.

7.4.3

Origin of magmas

Harland (1971) suggested that shearing in the Silurian transpressive regime could have raised temperatures in the deeper Stubendorffbreen Supergroup rocks to generate granitic magmas. The Chydenius Batholith, especially, while marked by a thermal aureole extending horizontally to 1 km may have completed its diapiric emplacement in a relatively cool state so as to give the strength to shoulder away the near vertical N-S-striking strata and so causing significant attenuation. The thicknesses are locally reduced to about half. An ensialic origin is assumed. However, the early stages of intrusion truncated the Hecla Hoek strata.

7.4.4

Lamprophyre dykes

Some lamprophyre intrusions, long noted in Ny Friesland, and a monchiquite dyke by Teben'kov et al. (1996), but not investigated fully. They would appear to be related to the late phases of granitic intrusion. The lamprophyre dykes are unlikely be of the same suite as that at Krosspynten (monchiquite and camptonite), on the west side of BFZ, which are possibly of Bashkirian age (Gayer et al. 1966) and in another (allochthonous) terrane.

7.5

The Hecla Hoek Complex: the continuing debate

Hecla Hoek rocks are the core of Ny Friesland. The name, coined by Nordenski61d in 1863, comes from the mountain (now Heclahuken) named after Parry's ship H M S H e c l a that wintered at its foot in Sorgfjorden in 1827-8. Nordenski61d at first used the name for most of the rocks of Svalbard older than the (Carboniferous) Mountain Limestone. He included the ?strongly metamorphosed rocks, on the one hand, and the Old Red Sandstone on the other and all rocks of intermediate age. Nathorst (in Suess 1888) excluded the metamorphics as Archean and the Old Red Sandstone as the Liefde Bay System. His Hecla Hoek in Ny Friesland is equivalent to the upper two of the three supergroups earlier referred to as Upper, Middle and Lower Hecla Hoek. As already argued the use of the name Hecla Hoek for rocks west of the Billefjorden Fault Zone is not recommended. Many, however, still use it for any pre-Devonian rocks in Svalbard, seemingly on the assumption that all basement was Caledonian and then related spatially as now. A recurring question concerns the relationship between (a) the metamorphic rocks of western Ny Friesland i.e. Nathorst's Archean; Tyrrell's (1922) pre-Devonian basement complex; Fairbairn's (1933) 'western schists and gneisses' and (b) the relatively unmetamorphosed strata to the east regarded by all as Hecla Hoek. Such was a common problem in many Caledonian terranes in Europe, Greenland and North America. Three main options were under consideration: (i) that the western metamorphic rocks are basement i.e. much older than the eastern, being separated by a major diastrophic event; (ii) that the western rocks are older but pass relatively conformably up into the eastern; (iii) that the western rocks are the metamorphosed equivalents of the eastern. In both options (ii) and (iii) the age of metamorphism would be later than the age of the eastern rocks. These questions persisted as long as no comprehensive geological maps were available. Until 1955 no fossils had been found in Ny Friesland to give a clue as to the age of the eastern rocks. The problem was addressed over many years by the Cambridge group (from Fairbairn 1933; Harland 1941). This involved surveys:

114

CHAPTER 7

topographical (Harland 1952; Harland & Masson Smith 1962) as well as geological (e.g. Harland 1959; Harland et al. 1992). Annual expeditions from 1949 to 1964mostly by man-hauled sledges and small boats) involved many geologists especially: M. B. Bayly 1951, 1952, 1953; R. A. Gayer 1961, 1962, 1963; D. Gobbett 1958, 1959; W. B. Harland 1938, 1949, 1951, 1953, 1964, 1974, 1981, 1982; J. R. H. McWhae 1949; G. Vallence 1965, 1967; R. H. Wallis 1964, 1965, 1967; C. B. Wilson 1952, 1953, 1955, 1956, 1957. By 1955 the main problem seemed to be solved favouring the second option above: namely that a whole succession of strataabout 18km thick passed down from unmetamorphosed into metamorphosed strata and the age was Precambrian except for the top kilometre of strata which first revealed Early Cambrian S a l t e r e l l a r u g o s a to Wilson in 1955. The whole sequence was first published in outline (Harland & Wilson 1956) and revised with more information and international terminology (Harland, Wallis & Gayer 1966; Harland e t al. 1992) as shown in Figs 7.2 and 7.3. Further research enhanced the value of this succession, modified it, and is recounted in detail in Section 7.6-8. However, the succession as published was not at first challenged. Supporting evidence included: (a) the concordance of the main groups of rocks in similar sequence throughout Ny Friesland except for the lower units; (b) mapping of granitic gneisses as meta-sedimentary strata (volcanic or arkosic) within the succession, with some melting, remobilisation and minor intrusion; (c) the intense transpressive tectonism with bedding strike-slip juxtaposed higher and lower grades of metamorphosed rocks; (d) the chlorite zone boundary transgresses the stratigraphic boundary so that in the north even 'upper' Hecla Hoek rocks are so tectonized; (e) no major unconformity surface had then been identified though such might have been expected to be obscured within the intensely tectonized older rocks. On the other hand Harland (1941) described some of the rock units as nappes with attenuated lower limbs, i.e. thrust sheets. Moreover, Harland & Wilson (1956) admitted that the lowest units were so complex that they could well constitute a basement. It was also realised that with such intense shearing, discordant contacts could be smeared into concordance. It seemed unlikely that any major tectonism punctuated the succession above the lowest group. It was not thought that the overlying apparently regular and concordant sequence could contain a distinct orogenic episode. However, this tentative conclusion depended only on the rapid reconnaissance mapping of the whole area completed about 1965 which is inadequate in detail (e.g. Harland 1959; Harland et al. 1992). The above interpretation has been questioned and so it must be considered provisional. That is because a basement to the regular succession may be distinguished. Abakumov (1965) regarded the two lowest groups as basement, combining them in the Atomfjella Complex. D. G. Gee visited northern Ny Friesland with a view to collecting specimens to demonstrate by isotopic dating that there is indeed an ancient basement. For some time older Proterozoic dates had been rumoured (i.a Gee 1986) and the data when published (Gee et al. 1992) gave evidence for ages of granitoid rocks of 1700 1800Ma, said to be intruding sediments in the Harkerbreen Group. If the zircons analysed were not derived from an arkosic or igneous protolith it must be accepted that at least part of the Harkerbreen Group is Late Paleoproterozoic. Such an age by itself identified a tectonothermal event. But without accompanying structural stratigraphic evidence of a discontinuity in the sequence it need not represent an orogenic episode. This matter was developed by Gee e t al. (1992). One option thus appeared for a sequence without interruption back to at least 1800 Ma. This would not be impossible considering that a likely age for the oldest Veteranen Group rocks probably exceeded 800 Ma (Harland & Gayer 1972; Knoll & Swett 1985) and the underlying Planetfjella Group, first correlated with the Kapp Hansteen Group of Nordaustlandet, which appears to have consistent ages between 900 and 1000 Ma. G. M. Manby in an account (1990) used a structure radically different from that of Harland (1959). Applying an already agreed

Supergroup

Group

Formation

Member and character

Valhallfonna (220 m)

Profilbekken Olenidsletta

(S)

Z Kirtonryggen

(750 m)

S S n," S

S~ 8 Tokammane

(192 m)

Z

Dracoisen (245 m)

s

z

5

(N)

Nordporten Basissletta Spora

Upper Limestone Mbr i Middle Limestone Mbr! I Dolostone Mbr Lower Limestone Mbr

Didovtoppen Topiggane Bl~revbreen

Dolostone Shale Sandstone

Shales

Wilsonbreen (160 m)

6 members

Gropbreen (tillite) Member Middle carbonate Member Ormen (tillite) Member Slangen MacDonaldryggen

Dlostone Dolostones & siltstones

Petrovbreen

1111ite

Elbobreen

(362 rn)

Age Llanvirn Late Arenig

Arenig mremadoc-Arenig mremadoc

Early C a m b r i a n

? Ediacara Late V a r a n g e r

Early V a r a n g e r

Lower carbonate Member Mainly limestone Upper dolostone Backlundtoppen

wZ

Shale Middle dolostone Oolitic limestone

(360-700 m)

U.I~ n" E ~oo v ~ .~ o I~ ~ ~v

Draken (25-300 m) Upper limestone Stromatolitic dolostone Lower limestone Lower dolostone

Svanbergfjellet

(100~625m)

'~

Upper (pale) Member

6 limestone beds

Lower (dark) Member

4 limestone & dolostoee beds

Grusdievbreen (865 m)

Oxfordbreen (550 m)

Fulmarberget shale Enpiggen Upper Greywacke Upper Quartzite Lower Greywacke Lower Quartzite

Glasgowbreen

ilZl•

(540 m)

o

Kingbreen (-1500 m)

>

Cavendishryggen -J-- Rheaninden Beds Quartzite L _ Bl&rinterBeds BogenLimestone 6 divisions Galoistoppen 2 divisions

Kortbreen (1200 m) Vildadalen

(3250 m)

E i o ' O._o v.=_ 8_

Fl&en (1500 m)

Sturtian

Sturtian

Late R i p h e a n

Quartzite Member Limestone Member Ros~nflella (=Eosletta skam zone Manby & Lybeds) Albreen Alryggen T~breen upper Member Middle Member Lower Member

[? 950 Ma]

Sorbreen

(250 m)

o

x

Vassfaret (600 m)

zI.U

Bangenhuk

LLI~

~IT

g

Lower Member

(2000 m)

Femmilsjoen Flatoyrdalen

Rittervatnet

Amphibolites, feldspathites and psammites, with metatillites at the top

Feldspathic bodies

z

Upper Member Middle Member

(350 m)

[c.1750

Ma] (I) (3)

Psammitic pelites with graphite Marble and quartzite

P o l h e m (2000 m) incl. near basal Inastadse~lga conglomerate ' "lnstrumentberget

(5)

.1_

--

-

Granitic gneiss

Smutsbreen

Westbyf]ellet Bohryggen

,~t-e,l v

Ingstadseggaconglomerate

Fl&tan (3)

[< 131 7 Ma] (8) [C.1750

Ma] (3)

[<1190 Ma] (7)

Einsteinfjellet

Eskolabreen

LemstrOm~ellet Malmgrent]ellet

[c. 1750 Ma] (4) [? 2145 Ma] (2)

Sederholm~ellet

Fig. "/.2. Summary of the Hecla Hoek succession of Ny Friesland, based on Harland & Wilson (1956), Harland & Wilson (1966) and Harland et al. (1992), with numerical ages from (1) Gee et al. (1992); (2) Balashov et al. (1993); (3) Johansson et al. (1995); and (4) Larionov et al. (1995). The value of 950 Ma is by suggested correlation with Nordaustlandet; unit (5) introduced by Abakumov (1965); (6) Johansson et al. (1995). The diagram shows the units in their sequence and classification; (7) Gee & Hellman (1997); (8) Hellman et al. (1997).

NORTHEASTERN SPITSBERGEN

115

strike-slip zone within the Planetfjella Group he argued for a major tectonic event between the 'middle' and 'lower' Hecla Hoek, thus going back to option (i) above i.e. in which the basement is the whole Sturbendorffbreen Supergroup. This argument was countered (Harland et al. 1992) then resuscitated (Gee & Page 1995; Manby & Lyberis 1995) and again countered (Harland 1995) on the basis that the only systematic mapping yet done shows a conformable sequence, though admittedly highly sheared (Wilson 1958; Wallis 1969). It was again rejuvenated (Witt-Nilsson, Gee & Hellman 1997). However, Harland (1997) while confirming the concordance and indeed conformable relationship between the Veteranen and Planetfjella groups, noted two lines of evidence for an unconformity between the Planetfjella and Harkerbreen groups. This could mark the hiatus between the two groups but not sufficient to warrant a major orogenic episode, the older strata even though intruded and thrust still mapped out in a fairly consistent sequence. There is as yet no sufficient case to abandon the original description of this remarkable sequence. A further matter concerns the presence of basic igneous material. It is virtually absent from the upper two supergroups and the upper (Planetfjella Group) of the three groups in the lower Supergroup. The middle (Harkerbreen) Group is rich in amphibolite which had mostly been interpreted as volcanic lavas and tufts with some intrusions. The lower group comprises two formations. The upper (Smutsbreen) formation has almost no basic rocks and the lower (Eskolabreen) formation has both acid and basic gneisses and has always been a serious candidate for ancient basement. The question arises that if the Harkerbreen feldspathic rocks were mainly intrusive instead of pyroclastic then it would pose a problem for the underlying Smutsbreen Formation to have escaped conspicuous intrusion if they were originally beneath. There have been still older ages rumoured in the oldest complex which all along has been suspected as basement (Balashov et al. 1993). However, in spite of announcing a much older zircon date they found the sequence to be concordant. Then Larionov et al. (1995) found c. 1770 Ma zircons in these older rocks also uniting the oldest group with the Harkerbreen Group in Abakumov's Atomfjella Complex. Johansson, Gee et al. (1995) reported good isotopic ages (1720 and 1770 Ma) from zircons from granitic bodies at two levels in the Harkerbreen group in northern Ny Friesland. Larionov, Johansson et al. (1995) reported similar (c. 1750 Ma) ages in the lowest group of the Atomfjella complex. The consistency of these results then appeared to establish the Atomfjella Complex as late Paleoproterozoic with a probable gap up to 800 Ma before Planetfjella schists were formed. New data, kindly made available in advance of publication, throw new light on the problem. Gee & Hellman (1997) determined detrital zircon crystal ages by the zircon-lead evaporation method, which gave a wide span of ages from the metasedimentary Smutsbreen Formation, so indicating the original sources of sediments. The youngest two zircons ( l l 9 0 M a ) gave the maximum age for sedimentation. Similarly, Hellman et al. (1997) gave a maximum age of 1317 + 7 Ma for the Polhem Formation quartzites. Witt-Nilsson, Gee & Hellman (1997) using the above data added detail of the Polhem basal conglomerate, with a reinterpretation of the Atomfjella Antiform with consequent stratigraphic adjustments. The interpretation of all the above data may now be reviewed again. (a) First giving primary reference to stratigraphic-structural observations, the following may now be taken as established.

Fig. 7.3. Generalized geological map of Ny Friesland outlining the distribution and subdivision of the Hecla Hoek Complex (adapted with permission of Cambridge University Press from Harland et al. 1992 and Johansson et al. 1995).

(i) All authors from Harland (1941) onwards recognized that the Caledonian deformation involved significant thrusting and nappe formation and, with one exception (Manby 1990; Manby & Lyberis 1995), agree with westerly vergence. (ii) There is general agreement that the intense sinistral Caledonian shear (transpression of Harland 1971) affects the whole structure west of the Veteranen Line.

116

CHAPTER 7

(iii) The Veteranen Line is the boundary between the overlying Veteranen Group and the Planetfjella Group and has been taken as a conformable sequence (Harland & Wilson 1956; Wilson 1958; Harland, Wallis & Gayer 1966; Wallis 1969) on the basis of field observations. Others who have opposed this conclusion have not contradicted the field evidence, but rather argued in support of their speculative terrane boundary. Though admittedly faulted, the succession is taken here as first proposed. (iv) An unconformity, above the Harkerbreen Group must be assumed on the basis of Abakumov's unpublished map showing successive formations of the Harkerbreen Group wedging out northwards against the overstepping and overthrust Planetfjella Group, and the comparison of the Harkerbreen successions from south to north as plotted by Johansson e t al. (1995) and pointed out ( H a r l a n d 1996). (v) An unconformity beneath the Polhem Formation where it rests on the newly established Instrumentberget-Fl5tan granitoid rock with basal conglomerate including granitoids of the same age (Johansson et al. 1995; Helhnan et al. 1997). (vi) Witt-Nilsson, Gee & Hellman (1997) named four nappe units each resting on a thrust of the nappe name. According to (iii) above the uppermost nappe is an integral part of the whole succession above the Harkerbreen Group. Moreover, the four main metasedimentary Harkerbreen formations appear in the succession in the same sequence as originally listed. It might appear that the Caledonian nappes have not significantly disturbed the original stratal sequence. It does, however, show that the Planetfjella Group is thrust over the lower metasedimentary (Polhem) formation of the Harkerbreen Group. (vii) Witt-Nilsson et al. (1997) showed that the Atomfjella Antiform continues from south to north of Ny Friesland and that the northern axis is displaced 3.5km eastwards from the position suggested by Gayer (1969), which simplifies the correlations in the succession and by introducing the Instrumentberget-Flfttan granitoid unit. They found beneath the Polhem Formation and to the north beneath the Instrumentberget granitoid, in the extreme north and in the axis of the antiform, rocks which match the Smutsbreen Formation. This suggests continuity of the relationship between the Harkerbreen and underlying Finnlandveggen groups through a distance of 130 km. (b) To the above field observations the following isotopic age w o r k m a y be s u m m a r i z e d thus. (i) The Caledonian age of the main deformation and metamorphism is confirmed as Silurian (Gayer et al. 1966; Gee & Page 1994). (ii) All the principal granitoid/feldspathite units gave zircon ages clustered around 1750 Ma. (iii) The only two (lowest) sedimentary formations so far investigated suggest that they could not have been formed earlier than 1100 or 1300 Ma (Gee & Hellman 1997; Hellman et al. 1997). (c) F o r interpretation of the above at this early stage only two hypotheses a p p e a r to survive and others m a y well be needed. (i) The granitoids (feldspathites) with consistent zircon ages of about 1750 Ma were at first confidently asserted as intrusive granites into older sedimentary formations (Gee et al. 1992; Johansson et al. 1995), but now the sedimentary units appear to be younger. Witt-Nilsson, Gee & Hellman (1997) and Gee (1996) reinterpreted the granitoids as being basement to the metasediments. Thus each nappe unit comprises granitoid basement beneath a different formation and stacked so as to give the originally recorded stratigraphic sequence, and as mapped by Abakumov to the east. (ii) The original conception based on the appearance of the granitoids/ feldspathites being concordant within the stated succession and so being metavolcanics need not yet be superceded. This explanation would fit the idea of an original stratal sequence, but now with two minor unconformities, whch did not unduly disturb the succession downwards without any major orogenic break. The difficulty with this is to account for the consistent c. 1750 Ma zircon ages of the geochemically cogenetic feldspathites. It just might be that an older granite of that age, say to the north of Ny Friesland, was melted and produced a succession of rhyolites and ignimbrites within the stratal succession. Under intense Caledonian metamorphism, gneisses or even granitoids would be formed, with some mobilization and intrusive contacts. This would account for the 'plutonic' zircons. This p r o b l e m has occupied the a u t h o r off a n d on since field w o r k in 1938 a n d he hopes to survive to learn the answer.

7.6

Hinlopenstretet Supergroup

H i n l o p e n s t r e t e t Supergroup, 1 . 9 k m ( H a r l a n d e t al. 1966; ' u p p e r H e c l a H o e k ' of H a r l a n d & Wilson 1956; H a r l a n d 1960, 1961, 1965). The S u p e r g r o u p crops out t h r o u g h o u t eastern N y Friesland and n o r t h w e s t e r n Olav V L a n d and in n o r t h w e s t e r n N o r d a u s t l a n det. It comprises two groups.

7.6.1 OslobreenGroup ( H a r l a n d & Wilson 1956; G o b b e t t & Wilson 1960) The Oslobreen G r o u p comprises a distinctive Early C a m b r i a n a n d Early to m i d - O r d o v i c i a n (Llanvirn) succession. It is d o m i n a t e d by c a r b o n a t e s of shallow m a r i n e facies. There are seemingly b a r r e n dolostone strata where Mid- and Late C a m b r i a n strata might be expected. The Oslobreen Series was first described in six units from central N y Friesland ( H a r l a n d & Wilson 1956; G o b b e t t & Wilson 1960). (6) (5) (4) (3) (2) (1)

U p p e r Oslobreen Limestone, 500 m M i d d l e Oslobreen Limestone, 220 m K i r t o n r y g g e n Dolomite, 85 m L o w e r Oslobreen Limestone, 160m Oslobreen Dolomite, 200 m Oslobreen Sandstone, 4 5 m

Wilson h a d discovered the first fossils in the N y Friesland Hecla H o e k strata with the Early C a m b r i a n S a l t e r e l l a r u g o s a in units (1) and (2). W h e n H a r l a n d , Wallis & G a y e r (1966) retermed the succession as the Oslobreen G r o u p with two formations, the K i r t o n r y g g e n F o r m a t i o n comprised units (6) to (3) and units (2) and (1) became the T o k a m m a n e F o r m a t i o n . H i g h e r strata were later discovered and n a m e d the Valhallfonna F o r m a t i o n above the K i r t o n r y g g e n F o r m a t i o n and the m o r e complete succession in northeast N y Friesland became the better standard (Fortey & Bruton 1973). The three formations are thus: Valhallfonna F o r m a t i o n (Mid-Ordovician) K i r t o n r y g g e n F o r m a t i o n (Early Ordovician) T o k a m m a n e F o r m a t i o n (Early C a m b r i a n ) Valhallfonna Formation, 220 m (Llanvirn limestones). The formation was set up after discovery on the north eastern coast of Ny Friesland and exposed in the cliffs along Hinlopenstretet of richly fossiliferous strata by CSE in 1965 (Vallance & Fortey 1968). It was described systematically by Fortey & Bruton (1973). The marine fauna has been only partially described, especially its trilobites and graptolites, from collections made first by CSE and later by the Natural History Museum, London and Palaeontological Museums, University of Oslo. From these the following work has arisen making this Llanvirn fauna one of the richest in the world. Whittington 1968, Fortey 1971, 1974a, b, 1975a, b, 1976, 1980; Fortey & Holdsworth 1971; Archer & Fortey 1974; Bockelie & Fortey 1976; Bockelie & Yochlson 1976, 1979; Fortey & Barnes 1976, 1977; Fortey & Whittaker 1976; Morris & Fortey 1976; Bockelie, Bruton & Fortey 1977; Fortey & Morris 1978; Cooper & Fortey 1977; Bockelie 1980; Cooper & Fortey 1982; Peel & Smith 1988; Bergstrom 1989; Smith, Sonderhom & Tull 1989; Cooper & Lindolm 1990). The Valhallfonna Formation was named from the ice cap, to the northeast of which the rocks are exposed along the coast. It was divided into two members as described by Fortey & Bruton (1973). Profilbekken Mbr, l l0m, is of massive limestone beds at the top grading downwards into well-bedded grey limestone strata. The top 5 m comprises grey-green shale. These softer beds may be the level at which higher strata were eroded away. The lower 5 m include beds transitional with the top of the underlying member faunally and lithologically. The base is taken at the occurrence of inarticulate brachiopods and phosphatised trilobites. The member contains an abundant fauna, mainly trilobites, representing at least 13 families and correlated with the middle Table Head Formation of Newfoundland i.e. White Rock Stage of mid- Ordovician age (Llanvirn). Olenidsletta Mbr, 145 m, of black and grey limestones and shales. The uppermost 43 m are of black limestone and shale 27 m of alternating black and grey

NORTHEASTERN SPITSBERGEN crystalline limestone beds. The lower 75 m are of black limestone and shale with an olenid trilobite fauna and a rich earliest Arening graptolite fauna. Kirtonryggen Formation (Harland, Wallis & Gayer 1966). The locality and the formation are named for John Kirton, an undergraduate of Queens College, Cambridge, who lost his life in 1958 on the mountain while collecting Early Ordovician fossils from this newly discovered locality (Harland & Wilson 1956; Harland 1958). His companion subsequently continued the study (Gobbett 1960; Gobbett & Wilson 1960). Four units (members) were described in this part of central Ny Friesland: at the type section in Kirtonryggen. (4) Upper (Oslobreen) Limestone Unit, 500+m, is formed of massive monotonous limestones with partial dolomitization giving a mottled appearance. The lower 200 m is fossiliferous. (3) Middle (Oslobreen) Limestone Unit, 200 m, of massive grey-brown cragforming limestone interbedded every 1-5 m with knobbly flags. It is often recrystallized shelly or oolitic limestone, with fecal pellets and algal nodules with Girvanella and trace fossils. Fossiliferous horizons yielded brachiopods and many trilobite species of Mid- to Late Canadian age. (2) (Kirtonryggen) Dolostone Unit, 70m, close-jointed, yellow-weathering dolomite siltstone interbedded with grey-brown porcellanous limestone, often partly silicified. (1) Lower (Oslobreen) Limestone Unit, 114 m on Kirtonryggen, up to 160 m north of Oslobreen is characterized by three main lithologic facies: (a) 'Knobbly flags', (b) massive fine-grained limestones with veins of white calcite, shell fragments faecal pellets and some stromatolites; (c) partly dolomitized limstones with pink to red patches and beds. Three fossil horizons occur in flaggy limestones in the middle of the unit with an early rugose coral, new species of trilobite Hystricurum wilsoni, the fauna being of Early Canadian age. Its base is marked by a sharp contact with the underlying dolostones. The above four units were named as divisions (members) of the Kirtonryggen Formation (Harland, Wallis & Gayer 1966). In northern Ny Friesland, north of the type locality, but below the Valhallfonna :Formation succession, Fortey & Bruton (1973) described the Kirtonryggen Formation with three members as follows: Nordporteu Mbr, 220 m, is entirely of limestone. The upper, 145m, is of light grey or brown massive limestone with thin bedded limestone intervals often stained black with stylolite surfaces and calcite veining often with hematite staining. The middle, 65m, of massive grey fossiliferous limestone with shaly interbeds The basal, 10 m, is of massive resistant limestone forming a headland. Detailed correlation has not been attempted, but it would appear that the Nordporten Member corresponds with the middle and upper (Oslobreen) Limestones of Central Ny Friesland (units 3 & 4 above). Basissletta Mbr, 250 m, of alternating dolostone or dolomitic limestone to limestone with a variety of facies. The upper 100+ m is only accessible with difficulty at low tide (in which about 40 m are not seen) is of micritic limestones with sparite and oosparite 2 m units, and shales. 50 m is of porcellanous dolostone often pale brown to black interbedded with dolomitic shale, with a variety of distinctive beds. 60 m is of alternating yellow weathering dolostone and grey limestone with stromatolitic horizons, oncolites and intraformational conglomerates. The lower 40 m is of cavernous bright yellow-weathering dolostone. The Basissletta Mbr correlates with the dolostone unit (2) above. Spora Mbr, 20 m, of fossiliferous massive limestone with some dolomite and hematite staining. The trilobite fauna is of Early Canadian age and correlates with unit (1) above. As generally applies in the north Atlantic region (northwest Scotland, East Greenland and Svalbard) Late and Mid-Cambrian faunas are missing and the dolostones between Arenig and Siberian are relatively barren. Swett (1981) noted that Early Ordovician conodonts are found only 160m above the Tokammane Formation so that late and mid-Cambrian time is either represented by the 100 200 m of seemingly barren strata and/ or by a significant time gap at the sharp lithological boundary change between the formations. Recent lower numerical estimates of the age of the Early Cambrian boundaries may reduce significantly the duration of Late and Mid-Cambrian time and hence the scale of the problem. Tokammane Formation. Wilson found cf. Salterella rugosa, (Billings) identified by C. Poulsen, the first Hecla Hoek fossil record in Ny Friesland (Harland & Wilson 1956) and the strata were established as Early Cambrian (Cowie 1974; Harland, Perkins & Smith 1988; Smith 1988). The lower two of the six Oslobreen units originally described were included in this named formation by Harland, Wallis & Gayer (1966).

117

Sedimentological studies followed (Swett 1981; Swett & Crowder 1982; Kidder & Swett 1989) and led to three members being established in Central Ny Friesland: (Swett 1981): The Ditlovtoppen Dolostone Member combines the upper and lower dolostone divisions of Harland & Wilson (1956) and Harland et al. (1966). The Topiggane Shale Member and The Blfirevbreen Sandstone Member is the sandstone division/member in the same two papers. Further palaeontological work was reported (Lauritzen & Yochelson 1982; Knoll & Swett 1987). In northeastern Ny Friesland Fortey & Bruton (1973) described the Tokammane Formation but without division into members. Tokammane Fm, in Central Ny Friesland Ditlovtoppen (dolostone) Mbr, 217 m, (descriptions from Swett 1981) The type section is composite from nunataks at Topiggane, Tokammane and Kirtonryggen. They are correlated on the basis of a Salterella-rich horizon 120m above the base of the member. The upper beds are medium crystalline dolostones weathering medium grey to greyish green with some mottling and stromatolitic structures. Some pebble-flake horizons are imbricated edgewise. Elongate nodules of coarsely crystalline cherts occur near the top of the formation. These may be evidence of former evaporites. Trace fossils (Planolites) occur. The top of the member is clearly distinguished by an abrupt change to the Kirtonryggen Limestone Formation. Salterella occurs in the middle and the top of the dolostone member making the whole of the Tokammane Formation no younger than Early Cambrian. Topiggane (shale) Mbr, 27 m, comprises green (glauconitic) to grey shales interbedded with thin, brownish weathering, glauconitic, phosphatic, and dolomitic sandstones. The unit forms a distinctive saddle between the more resistent members between which it lies. Swett (1981) distinguished this shale member because of its anomalous potash concentration which appeared to match that in the 'Fucoid Beds' of northwest Scotland and similar horizons in East Greenland and Newfoundland. It thus appears to be part of a widely distributed facies representing the weathering products of either volcanic sources or displacement of potash from illitic clays during dolomitization. The wide distribution may favour a cratonic weathering diagenetic origin rather than a volcanic source for which there is no other evidence at this time (Swett 1981). The potassium occurs as finely crystalline authigenic K-felspar (adularia). Kidder & Swett (1989) reported research that the phosphatic clasts in the Topiggane Member are of at least two kinds. Some resulted from diagenetic alteration of glauconite. Some pebbles were reworked concretions. The concretions may have been primary phosphatic deposits characteristic of earliest Cambrian sedimentation throughout the world as a result of oceanic upwelling at a continental shelf. However, in Spitsbergen the deposits are minor and formed apparently in a shallow shelf setting. Salterella occurs in the shale in Central Ny Friesland as well as in the overlying dolostones so indicating an early Cambrian age (Gobbett & Wilson 1960). Salterella has been regarded as belonging to the North American province. In the north an olenellid fragment was found 32 m from the base of the formation in strata probably equivalent to this shale member or to the dolostone member above. No correlation with Central Ny Friesland was attempted by Fortey & Bruton (1973), but their sequence was similar. Bl~revbreen (sandstone) Member, 33 m at south Tokammane appears to thin northwards. The sandstones are typically quartz arenites with 99+% quartz in medium to fine grain sizes and compacted with sutured interpenetration of quartz grains which, with acicular rutile inclusions, indicate a plutonic source. Occasional glauconite grains indicate a marine origin as do trace fossils especially in the north. Current laminations are typically planar. An Early Cambrian age is indicated by trace fossils Diplocraterion, Monocraterion and Scolithus in the northern exposures (Fortey & Bruton 1973) and confirmed by the occurrence of Salterella immediately above the sandstone member.

7.6.2

Polarisbreen Group ( H a r l a n d & Wilson 1956)

The Polarisbreen Group is d o m i n a n t l y o f shales with two tillite horizons o f w h i c h the u p p e r is the m o s t distinctive having exotic in a d d i t i o n to intrabasinal stones. T h e tillites in ' G o r g e Valley' in n o r t h N y Friesland were first identified by F l e m i n g & E d m o n d s

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(1941). Tillites were identified elsewhere in central-eastern N y F r i e s l a n d a n d the n a m e P o l a r i s b r e e n Series was i n t r o d u c e d by H a r l a n d & W i l s o n (1956). T h e P o l a r i s b r e e n G r o u p o f three f o r m a t i o n s : D r a k o i s e n , W i l s o n b r e e n a n d E l b o b r e e n was f o r m a l i z e d by H a r l a n d , Wallis & G a y e r (1966), the m i d d l e f o r m a t i o n being c h a r a c t e r i z e d by the c o n s i p i c o u s tillite: A t t h a t t i m e the o p i n i o n t h a t such tilloids were glacigenic deposits was being c h a l l e n g e d (e.g. K l i t i n 1960, 1964, 1965; C r o w e l l 1964; K r a s i l ' s h c h i k o v 1967; S c h e r m e r h o r n 1974), b u t also s u p p o r t e d ( H a r l a n d 1964; H a r l a n d , H e r o d & Kinsley 1966; H a r l a n d & H e r o d 1975). F u r t h e r C S E fieldwork in 1981 a n d 1982 established the earlier tillite w i t h i n the E l b o b r e e n F o r m a t i o n a n d elsewhere ( H a m b r e y 1982, 1983; F a i r c h i l d & H a m b r e y 1984). O n e o f the genetic p r o b l e m s was the a b u n d a n c e o f c a r b o n a t e s associated w i t h these glacial deposits. It was a d d r e s s e d by isotopic investigations (Fairchild et al. 1989; F a i r c h i l d & Spiro 1987, 1990) a n d a cold w a t e r e n v i r o n m e n t was c o n f i r m e d . A c o m p e h e n s i v e d e s c r i p t i o n o f V e n d i a n strata t h r o u g h o u t S v a l b a r d ( H a r l a n d , H a m b r e y & W a d d a m s 1993) i n c l u d e d a definitive a c c o u n t o f these strata in S v a l b a r d w h i c h is the source o f the following detail. Dracoisen Formation, 525 m, is the upper Polarisbreen Shale of Harland & Wilson. Although no disconformity has been noted at the top, micropalaeontological studies suggest a depositional hiatus spanning the time interval equivalent to the Late Ediacara and early Siberian beds of Eastern Europe (Vidal & Knoll 1982; Knoll & Swett 1987, 1990). Microfossils include Bavinella faveolata, Protosphaeridium sp., thin-walled leiosphaerids and rare acritarchs, which collectively indicate a Vendian age. As the underlying member is probably of Late Varanger age it is reasonable to suggest an Ediacara age for the Dracoisen Formation. The formation reflects a dominantly marine lacustrine environment following abruptly the glacial conditions of the underlying Wilsonbreen Formation. The uppermost of the six members show evidence of drying out and evaporitic minerals: anhydrite/gypsum and halite (Hambrey 1982). (D6) Upper Dolomitie Shale Sandstone Mbr, 150 m, the upper contact is obscured. The member is of a fine-grained dolomitic green sandstone interbedded with highly dolomitic maroon mudstone. Mudstone layers show evidence of atmopheric exposure with desiccation structures and rain pits. Small nodules appear to have originated as anhydrite or gypsum crystals. (D5) Middle Dolostone Mbr, 10m, is of pure cream-weathering, grey laminated dolostone and minor limestone; similarly with desiccation cracks and evaporite pseudomorphs. (D4) Middle Dolomitic Shale Sandstone Mbr, 150 m, is of finely laminated, fissile black, dark-grey and brown-weathering shale. Is not dolomitic and not well exposed. The lower contact is not exposed. (D3) Black Paper Shale Mbr, 150m, is of finely laminated, fissile black-, dark grey-, brown-weathering shale. It is not dolomitic and not well exposed. The lower contact is not exposed. (D2) Impure Carbonate Mbr, 105m, shaly dolostone and limestone with uniform parallel lamination. (DI) Basal Dolostone Mbr, 20m, was the 'third pale band' of Wilson & Harland (1964) and transferred to the Dracoisen Formation (Hambrey 1982). The member is of maroon laminated fissile dolostone, the laminations defined by variation in organic matter, silt or cement content. There is a sharp channelled contact at the base with the underlying formation. Wilsonbreen Formation, 160-170 m, is the Polarisbreen Tillite of Harland & Wilson (1956), Wilson & Harland (1964). It is the principal diamictite in the Polarisbreen Group. Two tillite members are separated by the Middle Carbonate Member (Fairchild et al. 1989) and display ungraded rhythmites alternating sand and carbonate laminae with stromatolites and brecciation related to anhydrite/gypsum relicts. The thickness of the formation is constant over a distance of 55km but the thickness of the individual members varies. The two tilloid members (Gropbreen and Ormen) are rich in both intrabasinal clasts (of underlying Hecla Hoek strata) and up to one third of extra-basinal igneous and metamorphic stones of unknown provenance. Of these, red granites and pink grey gneisses are the most common. The tilloid units have been the subject of detailed investigation, establishing by many features and beyond doubt their glacial origin. The first glacial material was water-lain; striated carbonate stones are common. Ice sheet conditions with transport of subglacial moraine was the major process with intermittent glaciomarine conditions indicated by dropstones. A striated cobble pavement

at Ditlovtoppen and preferred orientation of stones suggested movement from the southeast (Chumakov 1968, 1978; Fairchild & Hambrey 1984). The diamictites rest on pale dolostones with evidence of periglacial environment the isotopic evidence is of a cold water environment. Wilsonbreen Fm (W3) Gropbreen Mbr, 73m, is a diamictite with minor sandstone and siltstone. (W2) Middle Carbonate Mbr, 3-10 m, is a limestone of ungraded rhythmites alternating sands and carbonate laminae with stromatolites. Some distortion and brecciation suggest collapse from evaporite disolution of anhydrite and gypsum. Fairchild et al. (1989) reported oxygen and carbon isotopic studies which concluded that glaciation extended to low latitudes. (W1) Ormen Member, 85 m, is similar to (W3) but has a minor breccia. The top is sharp and there is top of a basal conglomerate on the underlying formation which was already indurated and with frost wedges indicating subaerial exposure. Elbobreen Formation was the Lower Polarisbreen Shales of Wilson & Harland (1964) and was so named by Harland et al. 1966. It was redefined and divided into four members including a further diamictite the Petrovbreen (E2) Member (dolomitic) by Hambrey (1982) and Fairchild & Hambrey (1984). (E4) Slangen Mbr, 14-28 m, is the 'first pale band' of Wilson & Harland (1964) is of cream or white-weathering dolostone and comprises three distinct divisions (Fairchild & Hambrey 1984). The upper division (unit C) is of sub-millimetre laminae of silt and dolomicrite, locally peloidal, oolitic or intraclastic, and stylolitic. The middle division (unit B) is of oolitic dolostones The lower division (unit A) is of well-sorted dolo-arenites with cherts and quartz probably after calcium sulphate. The base is transitional. (E3) MaeDonaldryggen Mbr, 145m, grey, laminated, shaly-muddy dolostones with siltstones and pure dolostones. (E2) Petrovbreen Mbr, 2+ to 42 m, a highly dolomitic diamictite, wacke and mud rock, variable in thickness with a sharp base, sandstones and clayey siltstones. The whole clast content may be matched with the underlying member except for rare volcanic fragments and black limestones. The stones are often striated and flatiron shaped, similar in many respects to those of the Wilsonbreen tillites except for a lack of conspicuous extra-basinal clasts. The unit was described in detail by Fairchild & Hambrey (1984) and environmental conclusions were again summarized by Harland, Hambrey & Waddams (1983) and discussed here in Chapter 13. (El) Lower Carbonate Mbr, 180m, is dominated by bluish black or grey limestone. It was redefined by Hambrey & Fairchild (1984) from the Lower Limestone Member of Hambrey (1982) by including dolostones and sandstones directly beneath the Petrovbreen Member. The upper division, 27m, is represented by pale yellow-weathering stromatolitic dolostone with bioherms up to 3 m (the largest being 10 to 50 m diameter and up to 6 m high) and spaced at 30 to 60 m. Grey dolomitic shales of E2 pass down into dropstone-bearing strata. Anhydrite-bearing silicified dolostones are also common and some rare cherts occur. This division passes down into Quartz arenites, 5 m, with subordinate shale and shaly limestone. Below this division is the main bulk of the member (El) which typically is of uniform bluish grey to black limestone with calcite veining from later deformation. The Polarisbreen Group is thus characterized by the upper (Dracoisen) formation, probably of Later Vendian (Ediacara) age. The middle (Wilsonbreen) formation is certainly of late Varanger age (Mortensnes Stage) and the lower (Elbobreen) formation is of early Varanger age (Sm~lfjord Stage) both early Vendian. It represents a siliciclastic interlude of cold and glacial conditions between the carbonate groups above and below, which formed in warmer environments.

7.7

Lomfjorden Supergroup

(Harland,

Wallis & Gayer

1966)

T h i s is the m i d d l e Hecla H o e k , c. 6 k m , o f H a r l a n d & Wilson (1956). It c o m p r i s e s two g r o u p s (series): A k a d e m i k e r b r e e n a n d V e t e r a n e n , each later defined by f o u r f o r m a t i o n s ( H a r l a n d , Wallis & Gayer, 1966). T h e u p p e r g r o u p is d o m i n a t e d by c a r b o n a t e s a n d the lower g r o u p by siliciclastics. It is o f N e o p r o t e r o z o i c (Late R i p h e a n to Sturtian) age f o r m i n g over a d u r a t i o n o f at least 200 million years a n d m a y r e p r e s e n t the d e v e l o p m e n t o f a subsiding i n t r a c r a t o n i c basin b e g i n n i n g w i t h r a p i d clastic s e d i m e n t a t i o n

N O R T H E A S T E R N SPITSBERGEN (following volcanic strata o f the u n d e r l y i n g g r o u p ) a n d w h i c h c h a n g e d into the stable c a r b o n a t e p l a t f o r m e n v i r o n m e n t o f the upper group.

7.7.1

Akademikerbreen Group ( H a r l a n d & W i l s o n 1956; W i l s o n 1961)

T h e A k a d e m i k e r b r e e n Series was described by H a r l a n d & W i l s o n (1956) with five c o n s t i t u e n t units each with u p to ten divisions. These were described in m o r e detail, p u b l i s h e d p o s t h u m o u s l y (Wilson 1961) w h i c h can h a r d l y be i m p r o v e d . T h e units were f o r m a l i s e d i n t o f o u r f o r m a t i o n s using the same n a m e s ( H a r l a n d , Wallis & G a y e r 1966). T h e g r o u p is very largely f o r m e d o f d o l o s t o n e s a n d limestones. Backlundtoppen Formation Draken (conglomerate) Formation Svanbergfjellet F o r m a t i o n Grusdievbreen Formation. S u b s e q u e n t l y the m a i n d e v e l o p m e n t s have been p a l a e o n t o l o g i cal with R u s s i a n studies o f k a t a g r a p h s , oncolites a n d s t r o m a t o l i t e s a n d by the A m e r i c a n studies o f m i c r o b i a l assemblages p r e s e r v e d in chert. The Russian studies were reported as follows: Raaben (1960, 1967); Golovanov (1967, 1976); Mil'shtein (1967-1976); Golovonov & Raaben (1967); Raaben & Zabrodin (1969); Mil'shtein & Golovanov (1979, 1983); Mikhaylova & Turchenko (1986) and with a study of carbonate in stromatolites (Fairchild 1991). The American studies as follows: Knoll & Calder (1983); Knoll (1984); Knoll et al. 1986; Swett & Knoll (1989); Derry et al. (1989); Knoll & Swett (1990). Bacldnndtoppen Formation, 360-700m, (Harland, Wallis & Gayer 1966). Originally this formation comprised an upper 'Backlundtoppen dolomite' unit with three divisions and a Lower Backlundtoppen oolite with three divisions (Wilson 1961). The formation is now described with the same six units or members, (Harland et al. 1992 confused B1 and B3). (B6) Upper Dolostone Mbr, 6-25 m, massive pale grey dolostone with large convex-downwards stromatolitic structures. These strata and the units below match well the Ryss6 rocks of Nordaustlandet. Wilson referred to this as 'dartboard dolomite'. (B5) Shale Mbr, 16-20m, dark quartzose and multicoloured shales. The shales are sharply distinguished from the dolostones above and below. The thickness is constant and four divisions can be traced extensively. 0.5 m quartzite, fine-grained, weathering orange; 1 2 m paper shales, purple, quartzose non-calcareous; 10 m paper shales green, quartzose non-calcareous; 5.10m mixed beds as above, weathering dark. (B4) Middle Dolostone Mbr, 150-250 m, massive pale grey dolostones. This main unit can be recognized everywhere by its resistant lithology, pale multicoloured weathering and absence of stratification. It is largely composed of massive or separated Collenia colonies with breccia and oolitic matrix. The stromatolitic structures are up 20 cm across and a metre high. There is some replacement by chert. (B3) Oolitic Dolostone Mbr, a dark grey dolomitic limestone, rusty weathering and irregularly bedded. Pale to coloured pisolitic and oolitic dolostones, often silicified, alternate with massive black limestone. (B2) Lower Dolostone Mbr, medium grey, pale-weathering coarsely stratified Dolostone with chert and Collenia. (B1) Oolitic Limestone Mbr, 100-300 m, thickly bedded dark grey to black cherty limestones with numerous oolitic and pisolitic bands, with subordinate flake conglomerates. Pale weathering dolostones also occur 0.5 to 4 m. Knoll, Swett & Burkhardt (1989) reported on biotas from the Backlundtoppen Formation which preserves five distinct microfossil assemblages occurring in distinct sedimentary environments. They noted a possible age range of 700-800 Ma but without explicit correlation (Sturtian on the scale used here). Draken (conglomerate) Formation, 25-300m, cliff-forming shale-like strata, dominantly dolomitic and with stromatolites, oolites and indeed all the lithologies in the Backlundtoppen Formation but with the distinguishing thick conglomeratic facies and the remarkably rich microbial cherts. Wilson (1961) listed 18 distinctive beds and with detailed descriptions especially of the gravelstones and flake conglomerates.

119

The succession may be summarized as follows: The upper 150m is of undifferentiated cherty dolostones, pale grey weathering grey-white, mainly thick bedded with abundant intraformational conglomerates often silicified with patchy or continuous bands of chert up to 1 m. There are also bands of Collenia dolostone, dark grey shale and oolitic or pisolitic facies. The lower 150m is formed of three or four units, similar to the above, separated by a variety of thinner beds. The formation as a whole is laterally variable in thickness and facies. This formation is noteworthy because of the rich microbial biota exquisitely preserved in the chert. (Knoll 1982a, b & c; Swett & Knoll 1985; Maliver, Knoll & Siever 1989, Knoll, Swett & Mark 1991; Fairchild, Knoll & Swett 1991). The key paper by Knoll (1982 in the Journal o f Paleontology) described an intraformational flake conglomerate with well preserved microfossils in silicified shards or microbial (cyanobacterial) mats formed in a lagoonal environment with at least three cyanobacterial benthos and a dozen planktonic taxa. Overall, of 28 taxa described, 8 were new. Knoll (1981) compared the biota with that of Bitter Springs. It is richer and probably of similar age (700-800 Ma). Svanbergfjellet Formation, 100-625m, is of limestone, dolostones, and Collenia strata divided by Wilson (1961) into four members, followed by Harland, Wallis & Gayer (1966) and Harland et al. (1992). It is a sequence of alternate limestones and dolostones. ($4) Upper Limestone Mbr, 3-115m, because there is some similarity with the Draken Formation, and some sections recorded are of doubtful correlation, the type section must be from Akademikerbreen where Wilson recorded seven units from the top: quartzites; black oolitic limestones; limestones and dolomitic flags; siliceous and dolomitic flags; calcareous flags; black oolitic limestones; and limestones and dolomitic flags. ($3) Stromatolitic Dolostone Mbr, 52-230m, this unique 'Svanbergfjellet Collenia' facies is penetrated by large scale stylolites and separated by thinner layers of multicoloured siliceous paper shales. ($2) Lower Limestone Mbr, 15-130 m, this member forms steep cliffs of thick bedded grey to black limestone generally iron stained and referred to by Wilson as 'Bolster Beds'. The base contains ochre-weathering cherty concretions up to 30 m and the upper beds are paler. (S1) Dolostone Mbr, 30-150m, this member of well bedded pale-grey dolostones and dolomitic limestones with black and white chert flattened concretions. The greater thicknesses are in Akademikerbreen which thin greatly in the north to Kluftdalen. More details were given by Wilson (1961). Butterfield, Knoll & Swett (1988 & 1994) reported on the paleobiology of the Neoproterozoic Svanbergfjellet Formation in which exceptional preservations of organisms including sphaeromorphic acritarchs, cyanobacterial sheaths, multicellular algae, complex protistan vesicles and probable heteromorphic bacteria providing an exceptional window on Neoproterozoic peritidal life. Of 63 forms reported 56 were treated taxonomically. These and other Proterozoic biotas are discussed in Chapter 12. Grusdievbreen Formation, 865 m. This unit was a series originally separated from the Akademikerbreen Series which comprised the above three formations as in Harland & Wilson (1956) and Wilson (1961) and included in the Upper Middle Hecla Hoek. Harland, Wallis & Gayer (1966) combined it with the three overlying formations to make the Akademikerbreen Group. The Grusdievbreen Formation (Series) was divided by Wilson (1961) into upper and Lower Limestone members with six and four divisions respectively as in Harland et al. (1992). (G2) Upper Limestone Member, 465 m in Akademikerbreen (6) Limestones banded, pale grey (5) Limestones banded, pale grey-black (4) Limestones banded, pale grey. (3) Limestones banded, pale grey-black. (2) Limestones banded, pale grey with massive base (1) Calcareous flags mainly red-brown. (G1) Lower Dolomific Member, 400 m in Akademikerbreen (4) Dolostone, pale weathering (3) Limestone black (2) Dolomitic Limestone, shales and flags (1) Dolostone, pale weathering.

7.7.2

Veteranen Group ( H a r l a n d & W i l s o n 1956; W i l s o n 1958)

3.8 k m , m a i n l y siliciclastics. T h e V e t e r a n e n Series was established by H a r l a n d & W i l s o n (1956) a n d described in m o r e detail by

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Wilson (1958) as the L o w e r Middle H o e k and divided as follows: Oxfordbreen Series U p p e r Veteranen Series Middle Veteranen Series L o w e r Veteranen Series Whereas this a c c o u n t follows Wilson, the n o m e n c l a t u r e was modified by H a r l a n d , Wallis & G a y e r (1966) and H a r l a n d e t al. (1992), as h e r e u n d e r , m a k i n g the four series into four formations respectively Oxfordbreen, Glasgowbreen, K i n g b r e e n a n d K o r t b reen. Hjelle (1965) c o n t r i b u t e d some additional detail and K n o l l & Swett (1985) reported on further microbial biotas, the oldest k n o w n f r o m Svalbard. H a r l a n d & G a y e r (1972), on the basis of likely sedimentationsubsidence rates in the strata above the Veteranen G r o u p , suggested that the age might well range from a b o u t 875 M a back to 900 or 920 Ma. Milstein & G o l o v a n o v (1979) m a d e the V e t e r a n e n G r o u p as o f late R i p h e a n age, say 670-950 M a on the basis o f s t r o m a t o l i t e s and microphytolites. K n o l l & Swett (1985) c o m b i n i n g their results f r o m material collected f r o m each of the formations with correlative rocks in N o r d a u s t l a n d e t suggested an age between 800 and 900 M a on the basis of acritarchs. The evidence is consistent, but not constraining. O n a likely correlation of the underlying Planetfjella G r o u p and the K a p p H a n s t e e n igneous rocks of N o r d a u s t l a n d e t , of w h i c h the latter has yielded ages in the range of 9 5 0 M a (Gee e t al. 1995), these estimates appear to be reasonable, but not established. M o r e o v e r the m a x i m u m age of the strata three groups below and beneath an u n c o n f o r m i t y appears to be 1190 M a (Gee & H e l l m a n 1997). All the above results are consistent with an age between 800 and 900 M a and the 4 k m of variegated, often shallow water strata could well have spanned that interval. Oxfordbreen Formation, 550 m. The formation, divided into two members, is of distinctive beds of dolomitic shales, quartzites and limestones, so distinguished from the overlying Grusdievbreen F o r m a t i o n dolostones and limestones. It was described by Wilson (1958) from five m a i n areas: Faksevfigen, lower C h y d e n i u s b r e e n , Polarisbreen, O x f o r d b r e e n - G r u s d i e v b r e e n , and T r a n s p a r e n t b r e e n . The following succession was described from Faksevfigen. Fulmarberget Shale Mbr, 210 m, (0.7) 140 m, pale highly dolomitic shales with some pure dolomite-siltstone, with a conglomerate near the top. (0.6) 70 m, interbedded pale and bright red-brown slightly dolomitic shales with layers of pale dolomitic quartzite. Eupiggen Mbr, 450 m, (0.5) dark green-grey shales and brown-weathering pale quartzose flags; (0.4) Passing into blue-black shales and flags. (0.5) & (0.4) non-calcareous and total 210m; (0.3) 90m, dark quartzose flags interbedded with dark limestones, some dolomitic; (0.2) 10m, grey-black bedded limestone-siltstones; (O. 1) 140 m, mixed dark beds. Glasgowbreen Formation, 540 m. Harland & Wilson (1956) referred to this unit as the Upper Veteranen Series, comprising two formations: Glasgowbteen Greywackes and Glasgowbreen Quartzites. Wilson (1958) divided the Glasgowbreen Greywackes into three units: Upper Greywacke, Upper Quartzite and Lower Greywacke the former Quartzite Formation becoming the Lower Quartzite. These four units were followed by Harland, Wallis & Gayer (1966) and listed as members by Harland et al. (1982). The following is from Wilson (1958) who described essentially only two lithological types. (G4) Upper Greywaeke Mbr is of clean greenish-black, fine-grained greywacke, finely laminated with darker and less dark laminae separated by carbonaceous fitness. (G3) Upper Quartzite Mbr is of coarse-grained, thickly bedded, pale pinkish, cross-bedded quartzites of uniform lithology. (G2) Lower Greywaeke Mbr of consistent lithology similar to (G4). (G1) Lower Quartzite Mbr is a prominent consistent unit similar to (G3) without other lithologies and with a sharp lower boundary. Knoll & Swett (1985), while generally confirming Wilson's successions questioned whether greywackes were not mixed tidal sandstones and shales. If so they would be consistent with the environments of formation of the quartzite members. Kingbreen Formation, c. 1500m. These rocks could first have been described by Fairbairn (1933, pp. 451-2) but not in sequence. Harland &

Wilson described the Middle Veteranen Series with three formations: Cavendishryggen Quartzites (300 m), Cavendishryggen Limestone (250 m), Galoistoppen Beds (c. 1000 m). The same rocks were described in considerable detail by Wilson (1958) from observations around Heklahuken, Dun6rbreen, Glintbreen, northern Veteranen, mid Veteranen, lower Chydeniusbreen and south Ny Friesland. He noted that the Middle Veteranen Series differed from the upper and lower series by much greater variety of strata. He divided the Galoistoppen Beds into upper and lower. Harland, Wallis & Gayer (1966) introduced the formation name and further division names, so making three members as listed by Harland et al. (1993) and followed here with Wilson's descriptions. 'Two thin lava bands occur at different horizons and localities. These are the only extrusions known from Ny Friesland in the Middle & Upper Hecla Hoek' (Wilson 1958, p. 313). Kingbreen Fm (K3) Cavendishryggen Quartzite Mbr was described by Wilson in three divisions. Harland, Wallis & Gayer (1966) followed by Harland et al. (1992) in systematising the naming of the units, without further explanation. To clarify the usage it is proposed to apply these two names to Wilson's observations pending further investigations as follows. Rheanuten Beds The upper division (of Wilson 1958) consists largely of 'black-coated' flags and shales with the same greenish quartzites as the middle division; greywackes and calcareous beds are subordinate. 4 m above its base is the 0.5m band of vertically jointed lava altered largely to calcite, chlorite in which the relic phenocrysts can be seen. Blfinuten Beds The Middle division (of Wilson 1958) is of dark uniformly medium-bedded, pale green-grey medium to fine-grained quartzites without other lithologies. The Lower division (of Wilson 1958) is of massive bands of variously tinted cross-bedded pure quartzite with thinner partings of rusty weathering quartzose shales and flags with few layers of dark dolomite limestone. Trail marks are common. (K2) Bogen Limestone Mbr. This unit is the renamed Cavendishryggen Limestone of Wilson (1958) which he described in six divisions (p. 317) only listed here. (6) 35 m, shales (5) 50-70m, calcareous beds (4) 4 35m, quartzose beds (3) 50 70 m, calcareous beds similar to (5) (2) 50 m, quartzose beds (1) 30m, limestones and dolostones. (K1) Galoistoppen Mbr. Following Wilson this is divided in two. Upper division Wilson listed 5 units at Faksevfigen (5) 180in, an assemblage of distinct lithologies including cream bands of cross-bedded fine dolostone with desiccation cracks and trail marks and fine green layers alternating with coarse cross-bedded pink quartzite. (4) 140m, mainly scree-covered mixture of rock types. (3) 30m, brightly coloured paper shales with dolomitic flags and a ferruginous quartzite bed. (2) l i0m, comprising 10m bands of differently brightly coloured noncalcareous paper shales. (1) 9 m, conspicous white quartzite marks the base. Lower division c. 700 m in Glasgowbreen, c. 450 m at Faksevfigen The upper 60m is finely laminated dolostone. The main rock type is of thickly bedded dark medium-grained quartzose greywacke. Two bands of altered lava, about 1 m thick occurred on the south side of Skinfaksebreen snout. One band has a pillowed upper surface and both have chilled margins top and bottom. Kortbreen Formation, 1200 m. This lowest unit of the middle Hecla Hoek, the Lower Veteranen Series was divided by Harland & Wilson (1958) into Veteranen Quartzites, 2150 m, and Veteranen Limestones, 10 350m. With more detailed observations Wilson (1958) described successions at Heclahuken, Dun6rbreen, the Fakse glaciers, northern Veteranen, midVeteranen, and Terrierfjellet and reduced the original estimate of thickness. Two members follow the original division. The Quartzite Mbr is of uniform petrology reflecting typical shallow water deposits. Rich in iron the colour varies, possibly in different tectonic situations. The Limestone Mbr, varies greatly in thickness and structure, but is always present beneath the quartzite member. Best seen by the Fakse glaciers is of dark grey limestone, siltstones, alternating with dolomitized equivalents. There are abundant oolites and some pisolites.

NORTHEASTERN SPITSBERGEN The Lower boundary of the Veteranen Group separates it from the Planetfjella Group in the Stubendroffbreen Supergroup (Section 7.8.1 below) and this boundary referred to (e.g. Harland et al. 1992) as the Veteranen Line has been the subject of some controversy (e.g. Gee et al. 1995; Manby & Lyberis 1995). Wilson (1958) summarized the field evidence from Harland & Wilson (1956) together with further observations. He reported (p. 306) on the boundary in at least six localities - from north to south: Sorgfjorden, Dun~rbreen, Skinfaksebreen, northern Veteranen, midVeteranen, and Terrierfjellet. Only in Terrierfjellet and northern Veteranen is there any evidence of structural irregularity at the contact. However, the stratigraphy corresponds so closely with that of Skinfaksebreen and midVeteranen, where the strata show every sign of conformity that such a fault is not likely to be of great throw. Further 'the metamorphic grade is always transitional across the boundary, though sometimes as in Dun6rbreen the transition appears to be rather rapid'. Further evidence is cited to conclude that the earlier views of Harland & Wilson (1956) are confirmed.

7.8

Stubendorffbreen Supergroup: succession ( o f H a r l a n d e t al. 1966)

This unit is the Archean of Nathorst (Suess 1888), the basement complex of Tyrrell (1922), the Western schists and gneisses of Fairbairn (1933) and the Lower Hecla Hoek of Harland & Wilson (1956) and of Bayly (1957). The whole or part of this unit, estimated at 12 + km thick, was a candidate for a proto-basement complex to the Hecla Hoek then reduced to the Atomfjella Complex (Harland, P o l a r R e s e a r c h 1997). The rocks are entirely metamorphosed and crop out throughout western N y Friesland: unlike the overlying units they have a range of igneous and sedimentary compositions suggestive of episodes of volcanic and related igneous activity almost throughout. Harland & Wilson (1956) distinguished three series: Planetfjella, Harkerbreen, and Finnlandveggen which were simply converted to group status as by Harland, Wallis & Gayer (1966). Abakumov (1965) and Krasil'shchikov (1965) proposed the Atomfjella Complex to combine the Harkerbreen and Finnlandveggen groups, confirmed by Harland (1996) as proto-basement. In anticipation of gravity surveys in Svalbard (Howells 1967); the Stubendorffbreen Supergroup, as an example of Caledonian basement, was sampled for density determinations (Howells, Masson-Smith & M a t o n 1977). F r o m the early sixties the St Petersberg group followed and extended the earlier Cambridge work but their detailed maps have not been published. However the map by Johansson, Gee et al. (1995), although based on Cambridge maps, added detail from Abakumov's unpublished work. This enabled mapping to the east of AsgSrdfonna to delineate the lower boundary of the Planetfjellet Group and in the south with the correlation especially of the Rittervatnet Formation. These revisions are included in the diagrammatic maps (Figs 7.3 and 7.4).

7.8.1

The Planetfjella Group (Harland & Wilson 1956; Harland et al. 1966; Wallis 1969)

The group, 4.7km, is dominated by metasediments with an acid volcanic component which increases downwards. Unlike the underlying groups no basic compositions (amphibolites) have been recorded. A distinctive feature of these feldspathic schists is their foliation and their spindle-shaped feldspathic aggregates. Fig. 7.4. Distribution of the Stubendorffbreen Supergroup in Ny Friesland (after Harland et al. 1992 and Johansson et al. 1995). The contact between the Planetfjella and Harkerbreen groups may have been mapped by Abakumov because the authors do not comment on it. It shows successive thinning and truncation northwards of the Sorbreen, Vassfaret and Bangenhuk formations, which is one of the arguments here for an unconformity without orogeny between the two groups to the east of the Atomfjella Antiform. Northern part revised after Witt-Nelson, Gee & Hellman (1997).

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Others have w o r k e d on these rocks, notably B l o m s t r a n d (1864), Odell (1927), Fleming & E d m o n d s (1941), Bayly (1957), G a y e r (1969) a n d K r a s i l ' s h c h i k o v (1979) w h o r e n a m e d the unit the M o s s e l h a l v o y a G r o u p - a j u n i o r s y n o n y m . M e t a m o r p h i c facies range from chlorite facies at the top to amphibolite facies with garnet, kyanite and staurolite at the base (Witt-Nilsson, Gee & H e l l m a n 1997). The two f o r m a t i o n s presently defining the g r o u p were described in detail in the n o r t h by Wallis (1969) from which paper the following s u m m a r y has been taken.

Vildadalen Formation, c. 3250m. First regarding the upper contact, Blomstrand (1864) in the north recognised the stratigraphically conformable contact with the overlying rocks and the transitional nature of the sedimentary lithologies. Fleming & Edmonds (1941) noted the conformable nature of the boundary in the Gullfaksebreen area and the uniform nature of the uppermost Planetfjella rocks from Sorgfjorden to Veteranen. The conclusions of Harland & Wilson (1956) confirmed by further work by Wilson (1958) as recounted for the overlying formation were further confirmed by detailed studies of Wallis (1969) who divided the formation into four members: Ros~nfjella, ,~lbreen, ,~lryggen and Tfibreen which alternate two lithologies. Whereas Wilson (1958) confirmed the consistency of the succession above the Planetfjella Group in which the lowest limestone unit is almost always present. Wallis (1969) showed that the uppermost (Ros6nfjella) member of the Vildadalen Formation is consistently adjacent to it. These observations in the north confirm Harland's reconnaissance traverses across the boundary (Harland & Wilson 1956). (V.4) Ros~nfjella Mbr, 1500m, is of fine-grained dark grey-green subpelites. The top 20 to 50m may be interbedded with 5m thick brown dolostone layers. 400 m below the top of the member are two further brown to orange dolomitic subpelites 15 m and 30 m apart. Down the succession, that is towards the west, deformation and recrystallization increase from a quart~chlorite-sericite assemblage with some plagioclase and tourmaline to increasing grain size, lightening of colour in which biotite and muscovite dominate. In the lowest 100 m horizons of pale pink feldspar phenocrysts up to 3 mm occur in a fine ground mass. These are the highest horizons in the PlanetfoJella Group with feldspar megacrysts. (V.3) Albreen Mbr, 400m, is distinguished by its contrasting beds of dolomitic and calcareous marble, subpelites, psammites and quartzites of which a 100m unit near the base is massive and persistent. The thicknesses and persistence vary along strike. The subpelites and psammites in particular are intensely folded and exhibit quartz hinges and feldspar megacrysts. (V.2) Alryggeu Mbr, 500 750 m, is of uniform subpelite lithology similar to that of (V.4) though somewhat lighter. Psammitic bands have recrystallized, biotite is the dominant mica, garnets are common and distort the ubiquitous microfolds with detached quartz hinges. The rock thus forms a foliated gneissose rock with quartz tension gashes. A characteristic Planetfjella Group lithology is a crenulated, foliated, megacrystic feldspathic psammite in horizons up to 10m thick with pink potash and grey plagioclase feldspars. Large feldspars up to 5 cm occur in a matrix of quartz-muscovite + plagioclase + biotite. Feldspar may constitute 50% of the rock. (V.1) Tfibreen Mbr, 450-800m, is analogous to the Albreen Member with horizons of marbles and quartzites as well as the characteristic feldspathic Planetfjella lithologies. Wallis (1969) gave three different successions in the north each with 5 - 6 units but varying greatly between them. The most constant feature is the basal marble unit. The distinctive Planetfjella lithologies may constitue half the bulk of the formation. Flfien Formation, 1500 m. The formation is distinguished from that above by the much greater occurrence of feldspar, yet retaining the typical close lamination of the Planetfjella Group. Whereas Harland, Wallis & Gayer (1966) noted three divisions, Harland et al. (1992) followed that paper rather than the later work of Wallis (1969) which is followed here with eight informal divisions. (F8) Upper subpelite division, 120m, of massive garnetiferous subpelites to psammites in which garnets reach 2 cm, with strongly contorted crenulation boudin necks with marked biotite foliation interrupted by the garnets. (F7) Upper variable division, 30-45 m, with marbles, subpelites and craggy feldspathite. Garnet megacrysts reach 4 cm. (F6) Upper felspathic-psammite division, 180m, is a massive craggy greyweathering unit with orthoclase and plagioclase feldspar megacrysts often euhedral, quartz axes produce rodding and there is extensive boudinage. (F5) Middle subpelite division, 40m, dark brown-weathering gneissose, garnet~luartz-subpelite, equigranular and little crenulated.

(F4) Lower felspathie-lrsammite division, 150m, pink-weathering, massive feldspathic psammite well foliated, crenulated with pink microcline megacrysts but mostly equigranular. (F3) Lower subpelite division, 30 m, is transitional from (F4) with increase in pelitic composition (biotite and garnet). (F2) Banded psammite division, 75m, with repetition of units, 0.5-1,0m each, with quartz-psammite base grading upwards into better laminated more pelitic composition. (F1) Lower variable division, 60m, a banded psammite passing downwards into more biotitic psammite in which crenulation produces marked lineation. The genesis of the distinctive rocks of the Planetfjella Group is discussed with problems of the origins of the metamorphic rocks of the whole supergorup in Section 7.9. To anticipate, it is clear that the Planetfjella Group derived much sediment fi'om an acid volcanic source. Wallis (1969) discussed the question in detail and showed, from a plot of four sections through the group from north to south of Mosselhalvoya, that the megacrystic felspathic lithologies thicken northwards so indicating a source in a direction with a northerly component. East-west comparisons are not possible in the steeply dipping strata. The Lower boundary of the Planetfjella Group with the Harkerbreen Group was discussed by Wallis (1969) who referred to the description of the northern outcrops of the Harkerbreen Group by Gayer & Wallis (1966). It is not so well exposed as the upper boundary and has yet to be mapped in detail. The contrast is marked from the laminated semipelitic Planetfjella lithologies to the Harkerbreen pure granular psammites with amphibolites. Moreover, 'the uppermost amphibolite unit seems to occur at the same general horizon' in relation to the boundary. The contact is well exposed for 5km from the NW corner of Mosseldalen where the boundary is taken below a 3 m persistent marble band above pale grey and pink equigranular granulose, slightly felspathic psammites interbanded with amphibolites, apparently concordant. However at many localities the contacts are thrust and indeed the whole complex has suffered intense tectonism. Krasil'shchikov (1973) showed a conformable upper contact, but a major break beneath his Mossel Series (Planetfjella Group). The revisions to the map afforded by Abakumov's mapping (in Johansson et al. 1995) provides clear evidence of discordance whether stratigraphic, tectonic or both, quite contrary to the same mapping which is consistent with a concordant upper contact of the Planetfjella Group. Exposures east of ~,sgfirdfonna show Vassfaret Formation in contact with Planetfjella rocks whereas in northern Ny Friesland the contact is with Rittervatnet and Polhem formations and in southern Ny Friesland with the Sorbreen Formation. Thus there would appear to be a somewhat progressive overstep of Harkerbreen Group Formations northward with a net loss of about 2 kin. Johansson et al. (1995) made this contact a 'major thrust'. This is confirmed by further mapping in the north (Witt-Nilsson e t al. 1997).

7.8.2

The Harkerbreen Group (Harland & Wilson 1956; Bayly 1957; H a r l a n d et al. 1966; G a y e r & Wallis 1966; G a y e r 1969)

The H a r k e r b r e e n G r o u p , 3.5 4.0 km, comprises quartzites, psammites, feldspathic schists and granitic gneisses, with mainly c o n c o r d a n t amphibolites. First described in the south f r o m sledge parties based on Billefjorden ( H a r l a n d & Wilson 1956; Bayly 1957), the T o r d e n r y g g e n rocks are d o m i n a t e d by pink quartzites and the Bleikfjellet by variable compositions. A m o r e detailed, sequence in the n o r t h was a d d e d by G a y e r & Wallis (1966), but it lacks the u p p e r strata of the southern succession. H o w e v e r , the group was defined by H a r l a n d , G a y e r & Wallis (1966) as comprising the Sorbreen, Vassfaret, B a n g e n h u k , Rittervatnet a n d P o l h e m formations. The rocks of this g r o u p have been the subject of studies f r o m the earliest days to recent times including Blomstrand (1864), Tyrrell (1922), Fairbairn (1933), Fleming & E d m o n d s (1941), H a r l a n d (1941) which were essentially disconnected. These were followed by attempts at regional synthesis by H a r l a n d & Wilson (1956), Bayly (1957). A b a k u m o v (1965) and Krasil'shchikov (1965) i n t r o d u c e d the concept of a b a s e m e n t comprising the H a r k e r b r e e n and F i n n l a n d v e g g e n groups u n d e r the n a m e Atomfjella C o m p l e x w h i c h usefully combines the H a r k e r b r e e n a n d F i n n l a n d v e g g e n

NORTHEASTERN SPITSBERGEN groups. Harland, Wallis & Gayer (1966) in a revision of the whole Hecla Hoek sequence discussed especially the Harkerbreen Group facies and associated with further detailed studies by Gayer & Wallis (1966), Gayer et al. (1966) and Gayer (1969). Then, after an interval, a new interest developed partly with improved isotopic age determinations as by Gee, Schouenberg et al. (1992), Gee, Bj6kelund & Stolen (1994), Gee & Page (1994) and renewed speculation by Manby (1990), Harland et al. (1992), Manby & Lyberis (1995), Harland (1995), Johansson et al. (1995), Larionov et al. (1995), Witt-Nilsson et al. (1997), and Hellman et al. (1997). In reviewing the history of investigations of the Harkerbreen Group it may be overlooked that in the middle of Ny Friesland the extensive Asg~trdfonna ice obscured a large part of the lower Planetfjella Group and the upper Harkerbreen Group so that correlation of units between north and south and between east and west may in some cases need to bridge a gap of 50 km. Moreover, when the logistic routine was by pack-carrying or man-hauled sledge from the south or small boats from the north, and after the initial reconnaissance of the fifties, studies in the sixties focused either on the north or south. Thus coherent correlation with detailed mapping remains to be done. Therefore the later (unpublished) work by A b a k u m o v and colleagues is welcome in that it fills part of the previous unknown. The Harkerbreen Group has attracted particular interest because of the interpretation of a variety of facies. The amphibolites have been interpreted as meta-tuffs and lavas with some basic intrusives, and the feldspathites were argued to have originated as meta-tuffs, ignimbrites and arkoses also with some intrusives. This interpretation was based on the stratiform nature of the bodies - their stratigraphic persistence often of quite thin beds over long distances, and occasional gradational compositions (Harland et al. 1966). However, the largest granite-gneiss sheet the Camryggen gneiss in the south and later subsumed in the larger Bangenhuk Formation, seen best in the north, has been regarded as emplaced by thrusting (Gee, Schouenborg et al. 1992; Gee, Bj6rkelund & Stolen 1994; Gee & Page 1994; Johansson et al. 1995) and later as basement (Witt-Nilsson, Gee & Hellman 1997). These papers report on Precambrian isotopic ages in contrast to the earlier determinations compiled by Gayer et al. (1966). Moreover, the geochemistry of the rocks has been applied to interpret the tectonic environment of their formation (Manby 1990; Carlsson, Johansson & Gee 1995), but with somewhat equivocal conclusions. Igneous textures have survived later deformation in the core of some amphibolite bodies and there could be some dykes and sills amongst the greater volume of volcanic basic strata. Gayer & Wallis (1966) proposed a shallow marine environment with volcanic lands to the west. The Rittervatnet Formation contained the upper two psephites (a metatilloid) which served as strain as well as possible climatic indicators (Gayer & Wallis 1966). The lower psephite has been reinterpreted as a basal conglomerate of the Polhem Formation (Hellman et al. 1997). The Atomfjella Arch is a southward plunging antiform which exposed Finnlandveggen Group rocks in its core to the south and so separates the two limbs which, because of structural complications, are not easy to correlate. However, the plunge is variable as the antiform continues to the far north. Moreover, most work on the group has been done either in the north or in the south with less information from middle Ny Friesland concerning the Harkerbreen Group which is exposed mainly in the western limb seen in coastal valleys or east of Asg~trdfonna on the eastern limb. Figure 7.4 follows the formation boundaries as modified from Harland et al. (1992) according to Johansson et al. (1995) which incorporates not

only the new zircon age determinations but also the available improved mapping of Abakumov. However the structural interpretation in that map is speculative. The major fault depicted along the Veteranen Line (Johansson et al.) is not supported by sufficient evidence. Breaks in the Harkerbreen Group successions are marked as thrusts (later named by Witt-Nilsson, Gee & Hellman 1997). These are noted below but have yet to be demonstrated by detailed mapping.

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Stubendorffbreen Supergroup Atomfjella Complex (Krasil'shchikov 1965) Harkerbreen Group Tordenryggen Subgroup, 1 to 2 km. This subgroup was based on the cliff sections in Harkerbreen which expose massive quartzites and psammites of relatively uniform composition dipping E and east of the Atomfjella Antiform. They have not been investigated in detail. Sorbreen Formation. The formation was named for the glacier reaching the sea on the east side of Widefjorden where the shore exposes clean fissile quartzites so that athough it correlates with the lower part of the originally defined Bleikfjellet rocks in the eastern limb, there is no complete measured sequence - a conclusion that is not difficult to entertain after a close study of the Ny Friesland glaciers. Indeed, in the north the contacts are often faulted cutting out the upper Tordenryggen Subgroup or obsecured beneath the fjord to the west. It comprises the Dirksodden Nappe of Witt-Nilsson et al. (1997). The rocks are primarily quartzites and psammites with variable feldspar and other content as described by Gayer & Wallis. Some compositional banding exhibits cross bedding so confirming the sequence. Distinctive feldspathic bands occur as typical meta-tuff which extend much of the length of the Wijdefjorden coast, composed of tabular plagioclase and K-feldspar megacrysts in a feldspar-quartz matrix. Concordant amphibolite horizons occur throughout with thicknesses ranging from 1cm to 30 m. By colour and competence contrast the ubiquitous boudinage is especially evident. Typically with 60-70% blue-green hornblende and 40-30% plagioclase (An20 30) with accessories quartz, biotite, iron ore, titanite and apatite. Often megacryst garnets occur. In some horizons Manby and Harland in 1981 and 82 observed N S bands of mylonite (Manby 1990; Harland 1992). Gayer & Wallis described the lower boundary as transitional. Witt-Nilsson et al. made the lower contact the basal Dirksodden Thrust, with some related granitoid features which gave a 1750Ma zircon age (Larionov in Witt-Nilsson et al. 1997).

Bleikfjellet Subgroup Vassfaret Formation, 600 m, defined just south of Femmilsjoen (Five Mile Lake) of mixed composition with traceable horizons of psammite and feldspathite and where best exposed three divisions are recognizable. (V.3) 320 m, quartz-biotite-polymictite with bands of feldspar psammitcs and calcareous polymictites. Intense folding of foliation has resulted in quartz rods from fold hinges. (V.2) 40 m, of two distinctive units an upper calcareous-hornblende-biotitepolymictite with garnet and a lower banded epidote psammite separated by a sharp boundary. (V. 1) 240 m, predominantly polymictic with calcite epidote concretions and bands of foliated concordant amphibolites. From residual sedimentary structures the concretions are interpreted as syn-sedimentary. The formation is interpereted as formed in shallow water by rapid deposition with contemporary basic pyroclastic input. It would correspond to the top of the Bleikfjellet subgroup in southern Ny Friesland, and has been so mapped by Abakumov. Bangenhuk Formation, 2000m, this unit was first distinguished in the south as the Camryggen gneiss with distinctive spindle shaped feldspars in an intensely lineated massive feldspathite. It is continuous with the Bangenhuk Formation to the north coast where it is divided into two members as seen best in Femmilsjoen. However, it may well correlate with more layers than in the south where the Camryggen gneiss in the eastern limb is much thinner. Femmilsjoen Mbr, 1250m, at the type locality and thins to 500m to the north. It is a markedly lineated gneissose alkali feldspathite. Orthoclase and oligoclase form 50 to 60% with quartz and up to 36% mafic bands of biotite (up to 17%) hornblende (less than 10%), epidote and titanite. Garnet is rare. The section by Gayer & Wallis (1969) shows fine nearly evenly distributed amphibolite horizons within the member. Flatoyrdalen Mbr, 735m, named from the valley south of Royal Societybreen on the west of the arch in middle Ny Friesland, is said to thin to 260 m east of the arch. It is formed of banded lithologies with up to 47% of potash feldspar. It is typically a medium-grained, banded gneissose, quartzose or psammitic feldspathite with mafic bands up to 5 cm of tabular blue-green hornblende. Schistose amphibolites similar to those in the Sorbreen Formation occur throughout with both sharp and gradational contacts. Harland, Wallis & Gayer (1966) concluded that the sedimentary origin of the formation is shown by the compositional banding including psammites of undoubted sedimentary origin and by the amphibolites

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representing basic pyroclastic deposits. This was originally evident in the south where amphibolites of varying thicknesses from a cm to many metres are interbedded with clean quartzites making it likely that amphibolite bands in feldspathites have a similar origin. Early ideas of magmatic or metasomatic origins for the granite gneisses were abandoned. Local evidences of granites were interpreted as a melted volcanic stratum. The matter is for discussion below. Nevertheless a magmatic intrusive origin was postulated by Gee et al. (1992) and subsequently. It seems likely that the Bangenhuk Formation has a greater feldspar content in the north because the typical granite compositions are matched in the south by the much thinner Camryggen gneiss, as seen at the head of Smutsbreen. The corresponding thickness being made up of quartzites. These southern investigations noted that above the 'Camryggen gneiss' was the 'Bottfjellet Band' of similar facies but only about 10 m thick. The latter unit specially exhibited gradational marginal facies from quartzite or psammite, through transitional facies with conspicuous isolated feldspar megacrysts, to a fully feldspathic gneiss. These observations, at the height of the magmatic-metasomatic controversy on the origin of granites, seemed to rule out a magmatic origin and suggested a metasomatic transition (Harland 1959). That was before some of the immense variety of volcanic products was preferred to provide protoliths of the granitic gneiss (Harland, Wallis & Gayer 1966). Zircons from a granite and gneissic granite of the Harkerbreen Group have been analysed by U-Pb and 2~176 single crystal method and have yielded ages of c. 1700-1800Ma. One of these granites intrudes metasediments, indicating [a late Paleoproterozoic] age for at least part of the Harkerbreen Group (Gee et al. 1992). Gee et al. concluded that significant segments of 'pre-Caledonian' crystalline basement are incorporated in the base of the Caledonian pile in northeastern Spitsbergen. The samples analysed were from locations shown on their map at Brennkollen, Femmilsjoen, Flhtan and Rittervatnet. Manby (1990) reported detailed chemical studies: (Section 7.9.2 below). Further determinations consolidating the above conclusions were presented by Johansson et al. (1995) when the zircons were characterized as plutonic rather than volcanic. Volcanic zircons were also identified in some of the meta-tuffs. Petrographic as well as detailed geochemical studies on the granitoids were reported by Carlsson, Johansson & Gee (1995) who noted that the granitic compositions throughout are 'cogenetic members of a single fractionation series'. Because the igneous component of the Bangenhuk Formation, with 1750Ma zircons, was thought to be intrusive in the Vassfaret Formation, Witt-Nilsson et al. (1997) combined both formations into a Bangenhuken Complex as the Nordbreen Nappe. They accounted for the distinction between the two formations as 'extensive shearing resulting in decoupling between the Bangenhuken Complex granites and the Vassfaret Formation metasediments'. Johansson et al. (1995) recorded the boundary between the Bangenhuk and Rittervatnet Formations as a major thrust. Witt-Nilsson et al. named it the Nordbreen Thrust and the Bangenhuken Complex their Nordbreen Nappe. Rittervatnet Formation, 350 m (Gayer & Wallis) up to 500 m (Witt-Nilsson et al.). The formation crops out in the northeast and west of the Atomfjella Arch. Rittervatnet is the lake just north of Femmilsjoen. The variety of distinctive strata enable more reliable structural observations to be made. Three divisions were recognised in the west but are difficult to correlate with different lithologies in the east where psephites are noteworthy. (Gayer & Wallis 1966). (R3) 72m, psammites with subordinate thinly banded (up to l m) psammitic sub-feldspathites, feldspathites, biotite subpelites and concordant amphibolites. Epidote is abundant, up to 30%; hornblende is a largely altered to chlorite. (R2) 160 m, is of uniform graphite-pelite to subpelite with thin marbles and quartzite as well as the usual thin bands of foliated schistose concordant amphibolites. The graphite is distinctive in the pelites which contain up to 60% mica. Quartz may amount to 35% and garnet is always present. The pure marbles contain up to 80% calcite giving a sugary appearance. Quartzite bands up to 0.5 m have sharp boundaries. (RI) 160m, in the west is of four distinct units. A thick foliated garnet amphibolite makes a clear top to (R1) below which is a thick white marble with over 80% sutured quartz. The Rittervatnet Formation in the east, as seen for example on the mountains some 10km southeast of Mosselbukta, is of approximately the same thickness but of different facies. Most notable are the two psephites, one at the top and separated from the lower one by about 300 m of banded

psammite, polymictites, feldspathite and amphibolite and underlain by about 50 m of polymictite has the appearance of a meta-tilloid with a variety of stones in a pelitic matrix. The dolostones being most competent have been squeezed and extended to fish-shaped spindles with axial ratios N-S of 10:1, limestones were flattened to ratios of 20-30:1 Witt-Nillson (1996?) noted conglomerate stones elongated in ratios of 40 : 3 : 1. The pelite matrix presumably attained much higher ratios. These tilloids give a clue as to the degree of deformation suspected throughout the supergroup by the prevailing linear and foliated fabric and indicated positively by the ubiquitous boudinage, all indicating N-S extension and later interpreted as extreme transpression. The original tilloid sedimentation was most likely by dropstones into mud from floating ice in a marine environment. It may be significant that feldspathite stones are rare. The lower horizon stones can be matched with underlying lithologies. The upper horizon contains over 20% that were not matched in Ny Friesland. The overall sedimentary pattern of the Rittervatnet Formation suggests a shallow marine environment in which the banded lithologies appear to have spread from the east. The carbonaceous content must imply significant biogenic activity with anaerobic conditions in local deeper water. Miscorrelation of units across the Atomfjella Antiform has been resolved not only by identifying the distinctly older Instrumentberget Formation (Johansson et al. 1995), but also by reinterpreting a psephite (probably the lower one) of the Rittervatnet Formation as the basal conglomerate of the Polhem Formation (Witt-Nilsson et al.) Polhem Formation, 900+ m (Gayer & Wallis) to 5000m (Witt-Nilsson et al.), named from Nordenski61d's 1872-1873 winter base and the name of his ship, is composed mainly of coarsely banded psammites and amphibolites. Indeed their similarity to those of the Sorbreen Formation and uniform light colour has posed a mapping problem where the succession is not clear. The psammites contain 60% quartz, other minerals vary, the dominant second mineral being oligoclase. Muscovite generally exceeds biotite. Because of its uniformity of facies the formation has not been divided. Gayer & Wallis (1966) gave more mineralogical details. The amphibolite strata range from a few centimetres to 30m and some less altered facies are doleritic with ophitic texture and appear as intrusive bodies. Nevertheless, the dominant impression is of concordant volcanics. The Polhem-Instrumentberget contact is marked by a basal conglomerate, the lngstadsegga conglomerate (member), with large granitoid clasts decreasing upwards and yielding zircon ages identical to the underlying granitoid (Hellman et al. 1997). Instrumentberget (granitoid) Formation. This is a previously unrecorded unit from a small outcrop in northern Mosselhalvoya at Fl5tan (about 5 km south of Verlegenhuken). Johansson et al. (1995) reported granitoid samples with plutonic zircons giving U-Pb ages of 1720-1770 Ma, the least deformed with ages around 1750 Ma. They interpreted these from two sheet-like units. One of these the well known Bangenhuk Formation referred to above and the other newly distinguished as a lower unit beneath the Polhem Formation and exposed at Instrumentberget (southeast of Mosseldalen). The Instrumentberget exposure yielded an age of 1737 +46/-41 Ma suggesting a coeval intrusion time of 1750 Ma. The unit was placed as the lowest of the Harkerbreen Group formations.

Lower boundary of Harkerbreen Group. There is a s h a r p transition f r o m highly q u a r t z o s e a n d feldspathic rocks often with a m p h i b o l i t e s to a distinctive p s a m m i t e with calcareous facies. This b o u n d a r y was m a r k e d as a m a j o r thrust by J o h a n s s o n e t al. (1995). It a p p e a r e d in the core o f the A t o m f j e l l a A n t i f o r m a n d is consistently b o u n d e d on their m a p by R i t t e r v a t n e t a n d P o l h e m f o r m a t i o n s on b o t h E a n d W flanks a n d over a N - S distance o f 6 0 - 8 0 or even 1 2 0 k m . F u r t h e r m a p p i n g in the n o r t h shows the P o l h e m F o r m a t i o n and, f u r t h e r to the n o r t h , the I n s t r u m e n t b e r g e t Fl~ttan F o r m a t i o n each resting directly on rocks o f p s a m m i t i c calcareous facies similar to the S m u t s b r e e n F o r m a t i o n to the south. T h u s there a p p e a r s to be no evidence o f a m a j o r u n c o n f o r m i t y , b u t the base is defined as the R e k v i k a T h r u s t at the base o f the R e k v i k a N a p p e o f W i t t - N i l s s o n e t al. 7.8.3

Finnlandveggen Group ( H a r l a n d & W i l s o n 1956)

W h e r e a s this, the lowest g r o u p , c. 3 k m , in the Hecla H o e k C o m p l e x , is a c o m b i n a t i o n o f t w o quite different f o r m a t i o n s :

NORTHEASTERN SPITSBERGEN Smutsbreen and Eskolabreen, its original distinction as a group stems m o r e from its contrast with the overlying H a r k e r b r e e n G r o u p than f r o m similarity o f its constituents. This contrast applies most particularly with the Smutsbreen F o r m a t i o n which could not be confused with any overlying strata. On the other h a n d the Eskolabreen F o r m a t i o n with its feldspathites and amphibolites could be confused with the H a r k e r b r e e n G r o u p except for their interbedded schists and marbles and their distinct plutonic fabric. The Smutsbreen F o r m a t i o n is clearly a m e t a s e d i m e n t a r y calcareous unit of psammites, semipelites, calc-schists and marbles of a distinctive mauve hue, or brown to orange where the calcschists and marbles have weathered, and exceptionally with amphibolitic bands. The Eskolabreen F o r m a t i o n is a complex of acid and basic gneisses of coarse grain size suggesting a plutonic m e t a m o r p h i c environment. Amphibolitic banding is typical except for some pink gneisses. Whereas the Eskolabreen F o r m a t i o n has from the beginning been suspect basement and possibly confirmed isotopically, the Smutsbreen F o r m a t i o n is a coherent metasedimentary unit overlying it and underlying the H a r k e r b r e e n Group. Nevertheless M a n b y (1990), thinking that m o s t of the H a r k e r b r e e n amphibolites are intrusions, suggested that the general lack o f Smutsbreen basites beneath the H a r k e r b r e e n rocks makes the Smutsbreen F o r m a t i o n younger and so tectonically inverted. It was clear from H a r l a n d ' s (1941) study in Stubendorffbreen that considerable nappe structures are present, nevertheless the overall stratigraphic succession appears to be consistent (e.g. Balashov et al. 1993).

Smutsbreen Formation, c. 1000m, (Harland & Wilson 1956). Smutsbreen Formation is seen in an antiform beneath the Harkerbreen rocks (Fig. 7.8a) especially well in the cliffs north of Stubendorffbreen and it forms the outer core of the Atomfjella Antiform extending through Lemstr6mfjellet to Smutsbreen (Harland 1941). At first sight it is a dark pelite with distinct light marble bands which are valuable as marker horizons. The formation as a whole ranges in composition from a foliated psammite of distinctive mauve tint with quartz stringers, the axes of isoclinal folds, though garnetiferous pelites to calc schists and relatively pure marble in two principal horizons (Harland 1941). The Atomfjella Antiform extends southwards where the formation is more accessible from Billefjorden, but less well exposed along the northern moraine of Nordenski61dbreen. Tyrrell (1922) and Fairbairn (1933). Amphibolite bands do not characterize the Smutsbreen Formation contrary to the impression from Harland & Wilson (1956). Indeed since the early reconnaissance reported there the further work, especially that of Bayly (1957) resulted in a reappraisal by Harland, Wallis & Gayer (1966) as follows: ($2) Westbyfjellet Mbr, c. 500m, includes the Westbyfjellet and Einsteinfjellet marbles of Harland & Wilson (1956) and the upper part of the Stormerfjellet schists of Harland (1959). Five divisions were listed. (5) c. 100 m, dark medium-grained schistose garnetiferous mica semipelite (4) 0-20 m, impersistent marble (3) c. 100m, as (5) (2) c. 100m, massive marble dividing into two or three horizons and associated with highly calcareous pelites. (1) c. 200m, calcareous garnetiferous schistose pelites and semipelites weathering to a fine golden colour. (S1) Bohryggen Mbr, c. 700m, is equivalent to the lower part of the Stormerfjellet schists, and probably the Lemstr6mfjellet schists of Harland & Wilson (1956). It is of uniform coarse-grained, foliated, compositionally laminated, garnetiferous psammite/semipelite characterized by a mauve or purple sheen on fresh surfaces, and sigmoidal quartz fold hinges. It contains rare psammites and exceptional amphibolites (Harland, Wallis & Gayer 1966). Eskolabreen Formation, 2000+ m, Harland & Wilson (1956). The underlying Eskolabreen gneisses are the least understood; the members distinguished may be in stratigraphic sequence or may be digitations of a nappe (Harland 1941; Harland 1959) or separate thrust sheets, e.g. of basement. If there is a pre Hecla Hoek basement, it is likely to have been remobilized and so be obscured in this formation. On the other hand there is a general concordant compositional banding and foliation throughout. The conclusions of Harland (1941), Harland & Wilson (1956) and Bayly (1957) were revised by Harland, Wallis & Gayer (1966) who distinguished four members:

125

(E4) Einsteinfjellet Mbr, c. 100 m, is a massive pink-weathering gneissose feldspathite, associated with coarse-grained semipelites. (E3) Lemstriimfjellet Mbr, c. 700 m, is similar to those of the Einsteinfjellet Member but alternating with coarse amphibolites. (E2) Malmgrenfjellet Mbr, 100~00m, consists of coarse-grained semipelites together with impersistent marble horizons. (El) Sederholmfjellet Mbr, 500+m, is of interbanded feldspathic and amphibolitic layers distinguished by very coarse granite texture suggestive of a plutonic environment. This is the lowest unit exposed beneath ice and Carboniferous cover to the south. Larionov, Johansson et al. (1995) reported U-Pb determinations on zircons from the Eskolabreen Formation as exposed in Stubendorffbreen. A band of muscovite biotite gneiss gave 1770Ma. Two samples of granite gneiss yielded a pooled upper intercept age of 1766+ 10Ma which was taken to date the age of the intrusion of the granite protolith. The lower intercept age of 404+8 and a similar U P b titanite age recorded the Caledonian metamorphic event (?Early Devonian). The consistency of this result with ages from zircons in the Harkerbreen Group in northern Ny Friesland leave little doubt that the feldspathites in the Atomfjella Complex comprising both the Harkerbreen and Finnlandveggen groups were formed at about the same time or derived from a common source. The temptation to correlate the Harkerbreen and Eskolabreen rocks should take into account the marble content only of the lower rocks. Balashov et al. (1993) reported without detail a zircon age of c. 2415 Ma from the Eskolabreen Formation.

7.9 7.9.1

Stubendorffbreen Supergroup: genesis Petrology

In classifying these rock types Bayly (1957) described six m a j o r lithologies: (1) pink quartzites; (2) variable quartzites, (3) granitic gneiss; (4) calc-schist and marble; (5) feldspathic schists and (6) mafic rocks (Fig. 7.5a). Both granite gneisses and mafic rocks have an igneous composition whereas the remainder are of sedimentary origin and often with a variable and significant igneous c o m p o n e n t . The purely igneous compositions presented a problem. In addressing it, and to avoid genetic prejudice, Wallis et al. (1968, 1969) used a working objective classification of m e t a m o r p h i c rocks according to the m a j o r mineral group present: quartzite > 90% quartz; psammites 80-50% quartz; feldspathite > 50% feldspar; marble > 50% carbonate minerals; pelite > 50% alumino-silicates; and amphibolites > 50% pyrobole, hornblende is generally > 60%. The granite gneiss (or feldspathite) compositional range is smaller than in adjacent beds and the main c o m p o s i t i o n is typical o f low-melting-point mixtures so that the 'last consolidation' was probably from a liquid, not f r o m 'detritus'. Bayly preferred a product o f refusion rather than a primary magmatic origin. H a r l a n d et al. (1966) further concluded that magmatic intrusions could not have p r o d u c e d such consistent stratal relations along strike (100km). This required a c o n t e m p o r a r y protolith such as lava, pyroclastics, arkose or combinations. A pyroclastic origin could account for the margins with transitional composition of some units in which lava or ignimbite might constitute the centre. Bayly's m e t a m o r p h i c facies m a p is shown in Fig. 7.5b. Intrusive contacts of the feldspathites have been noted by all authors and typical granitic compositions agreed by all. However, most recent authors have resuscitated an original option that the feldspathites are n o r m a l granitic intrusions into a sedimentary sequence (Gee et al. 1992; Gee, Bj6rkelund & Stolen 1994; J o h a n s s o n et al. 1995; Carlsson et al. 1995), all having zircon ages between 1700-1800 Ma. Subsequently, w h e n it turned out that some metasediments could n o t be older than c. 1190 Ma, the granite was interpreted as basement, and only one f o r m a t i o n (of u n k n o w n age) was intruded, the other granites being basement (Hellman et al. 1997). The alternative hypothesis o f c o n t e m p o r a n e o u s volcanic origin with relict zircons from remelted granite m i g h t take into account

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Fig. 7.5. (a) Petrological character of units in SW Ny Frieslan, after Bayly (1957). The numbers refer to stratigraphic units at that time as follows: (1) Planetfjella schists; (2) Tordenryggen quartzites; (3) Bleikfjellet quartzites; (4) Camryggen gneiss; (5) Smutsbreen schists and marbles; (6) Eskolabreen gneisses; (7) Austfjorden gneiss; (8) Cambridgebreen gneiss; (9) Sorbreen quartzites. (b) Metamorphic character of units in SW Ny Friesland, after Bayly (1957). Reproduced by permission of Cambridge University Press.

the power of ignimbrite flows (e.g. Brannery & Kokelaar 1997). Volcanics can have local intrusive relationships. The mafic rocks ('amphibolite') appear all to be of basic igneous origin. Indeed exceptionally some rock masses retain an igneous texture. Harland & Wilson (1956), Bayly (1957), Harland (1959) and Harland et al. (1966) all preferred a basic volcanic environment with possible tufts, lavas, sills and occasional feeder dykes. Again the banded rocks would be contemporaneous or pene-contemporaneous (contra Manby 1990). Some layers (e.g. a few millimetres thick and tracable some 100m or more) are unequivocally sedimentary. Their sharp contacts with quartzite suggest a direct pyroclastic origin rather than denudation from a basic source rock. A high sedimentation rate in a proximal volcanic environment would explain the sharp contacts. Thicker layers could be lavas and the rare cross-cutting units could be feeder dykes. Exceptional metabasites, often preserving igneous textures, might be of later (Caledonian) origin (Harland et al. 1966; Wallis & Gayer 1969) and if so it might be an igneous episode in a transtensional regime (Harland 1971). Manby (1990) on the other hand favoured all amphibolite bodies to have originated during the

deformation phase. How much this, if any, was Phanerozoic remains to be determined.

7.9.2

Geochemistry

Manby (1990) described the chemistry of the acid gneisses and amphibolites of the Harkerbreen Group. Compositions in terms of most elements were tabulated. Amphibolite. The element abundances are of basaltic calc-alkaline to tholeiitic composition and slight differences do not appear to reflect any genetic differences, for example with regard to concordance or discordance. Interpretative assessments suggest affinities with volcanic arc basalts, transitional volcanic arcs, back-arc basins and mid-oceanic ridge basalts so that no unequivocal matching could be found. Manby concluded (p. 144) that the 'Harkerbreen amphibolites represent basaltic to calc-alkaline magmatism in a rifted basin behind a magmatic arc, above a mature subduction zone'.

N O R T H E A S T E R N SPITSBERGEN Gneiss. W i t h 6 5 - 7 2 % silica the alkali silica A F M plots s p a n the t r a c h y t e - r h y o l i t e - r h y o d a c i t e a n d g r a n o d i o r i t e field. M a j o r , trace a n d rare e a r t h e l e m e n t ratios are b r o a d l y similar to rhyolites a n d have n o t suffered significant c h a n g e s t h r o u g h s u b s e q u e n t m e t a m o r p h i s m . Detailed analytical d a t a were t a b u l a t e d a n d p l o t t e d with the c o n c l u s i o n o f a r h y o d a c i t i c to rhyolitic 'within plate' setting in a possible rifting A t l a n t i c type m a r g i n . T h e c o n c l u s i o n here is t h a t valuable as the d a t a are they d o not actually discriminate b e t w e e n a n y o f the conflicting h y p o t h e s e s .

Bangenhuk

granitoids. C a r l s s o n e t al. (1995) described the g r a n i t o i d c h e m i s t r y a n d a r g u e d t h a t the feldspathic gneisses o f the B a n g e n h u k F o r m a t i o n were d e f o r m e d granites as seen in t r a n s i t i o n a l occurrences. T h e low strain facies c o n t a i n large m e t a s e d i m e n t a r y xenoliths. T h e y c o n c l u d e d t h a t granites a n d g r a n o d i o r i t e s are a m a j o r c o m p o n e n t o f the B a n g e n h u k F o r m a t i o n . T h e y were classified as A - t y p e with respect to m o s t g e o c h e m i c a l p a r a m e t e r s . E l e m e n t d i s t r i b u t i o n has n o t been significantly d i s t u r b e d by t e c t o n o t h e r m a l events. T r a c e e l e m e n t d i s t r i b u t i o n indicates s o m e heterogeneities o f m a g m a source a n d later c o n t a m i n a t i o n . Trace e l e m e n t a b u n d a n c e s , R E E p a t t e r n s a n d N d i s o t o p e characteristics indicate s o m e crustal c o n t r i b u t i o n r a t h e r t h a n direct m a n t l e d e r i v a t i o n . A g e d e t e r m i n a t i o n s suggest a single closely related magmatism.

7.9.3

Isotopic ages

T w o d a t a sets affirm the Silurian age o f the u b i q u i t o u s latest m e t a m o r p h i s m a n d tectogenesis. Krasil'shchikov et al. (1964) reported a whole rock analysis by K - A r on a biotite gneiss from Verlegenhuken (recalculated) 365 Ma, and Gayer et al. (1966) recorded K Ar determinations, especially from biotite in rocks in the NW corner of Ny Friesland. Garnet-mica schist from E end of Instadegga 419 + 5 Ma Paragneiss from E end of Instadegga 434 • 7 Ma Mica schists from N of Mosselbukta 426 + 8 Ma Paragneiss from Femmilsjoen 436 4- 9 Ma North shore of Adolfbukta 422 4- 6 Ma Except for the 365 Ma result all fall within the limits of the Silurian Period as estimated in Harland et al. (1990, 408.5-439.0Ma) and in this work (417-443 Ma). New data by more sophisticated technology confirm the above results, but more precisely as Silurian mainly Middle. Gee & Page (1994) reported 4~ determinations on eight samples. Muscovite from garnet-mica-schist at Rittervatnet 414-t-3 Ma Hornblende from amphibolite at Rittervatnet 428 4-4 Ma Hornblende from amphibolite at Rittervatnet 443 4-5 Ma Hornblende from amphibolite at Rittervatnet 424 + 3 Ma Hornblende from amphibolite at Polhem 421 + 3 Ma Hornblende from amphibolite at Polhem 423 + 4 Ma Hornblende from amphibolite at Polhem 421 + 3 Ma Muscovite from feldspar mica schist at Planetfjella 416 4-3 Ma Harland e l al. (1990) estimated the Wenlock interval at 424 to 430.4 Ma. From the scale adopted in this work one would be Llandovery, two Lochkovian, the rest Wenlock. The above data do not discriminate between the formations or even groups of the Stubendorffbreen Supergroup. Late Paleoproterozoic ages have been obtained as follows. (i) Manby & Lyberis (1991) reported Sm-Nd age determinations on Harkerbreen amphibolites yielding an age of 1757+90. The amphibolites were said to cut schistosities but few structural or stratigraphic details were given. However, analytic data and sample treatments were not provided for an independent check. (ii) Gavrilenko & Kamenskiy (1992) obtained 1.8 Ga from ultramafic rocks in Mosselhalvoya separating the Polhem Formation from the Planetfjella Group. An adjacent biotite rock yielded 500 Ma, both by K-Ar and Ar-Ar methods. Zircons tell a similar story surviving the Caledonian metamorphism and recording c. 1750 Ma events as follows.

127

(iii) Gee, Schouenborg, Peucat, Abakumov, Krasil'shchikov & Teben'kov (1992) recorded from granitic gneisses of northern Ny Friesland seemingly Bangenhuk Formation samples which yielded e. 1750 Ma ages. Two samples one from (a) an aplitic granite on the south side of Femmilsjoen and (b) one from a reddish grey gneissic granite, 100m south of Fl~ten north of Mosselhelvoya yielded zircons, which were carefully sorted. By U - P b analysis: Sample (a) from different fractions gave on upper intercept age: 1809 + 165/- 122 Ma Sample (b) gave zircons with less discordant ages of 1778 + 53/-45 combining all data a range of 1778 4-30 Ma was suggested. (iv) Gavrilenko & Kamenskiy (1992) by K - A r and Ar Ar methods on an ultrabasic body, presumbly stratigraphically below the Planetfjella Group, obtained a range of values through 271,469, 780, 1870Ma. (v) Balashov, Larionov, Gannibal, Sirotkin, Teben'kov, Ryungenen & Ohta (1993) gave an earliest Proterozoic age for zircon in the Eskolabreen gneiss south of Stubendorffbreen. The rock is a coarse-grained, feldspar porphyroblastic, garnethornblende-biotite gneiss with 25-30% plagioclase (An2045), 30-40% K-feldspar, 10% biotite, 1-2% each of hornblende and garnet with accessories of apatite, zircon, monazite and opaques and secondary chlorite, sericite and epidote. U - P b isotopic isochron gave upper intercept of 24154-34Ma. Balashov et al. argued that the Smutsbreen formations are conformable so that this age would apply to the Finnlandveggen Group as a whole. (vi) Johansson, Gee, Bj6rkelund & Witt-Nilsson (1995) gave further U-Pb zircon ages from seven further samples, both north and south, in the Harkerbreen Group. Ranging 1720-1770 Ma they centred on 1750 Ma, the zircons being of plutonic rather volcanic origin and intrusive within the units. From further mapping, two mappable granitoid sheets were distinguished. The Bangenhuk Formation extending the length of Ny Friesland and a lower Instrumentberget Formation exposed at Instrumentberget and already sampled at Fl~tan, both in the north. Moreover, a felsic metavolcanic within the Sorbreen Formation yielded 1750 + 8 Ma by the same method. Johansson, Gee & Larionov (1995) gave further support for an age range between 1720 and 1770Ma of six U - P b zircon results from undeformed granitoids within the Bangenhuk Formation. The seven results were as follows, the numbered localities being shown on Fig. 7.4 and suggested magmatic crystallization events. (1) Brennkollen 1759+ 1 9 / - 1 4 M a 1748 4- 8 Ma (2) Einsteinodden (3) Gyldensk61dholmane 1728 + 2 1 / - 1 8 Ma (4) Reinbokkbreen 1766+43/-35 Ma 1724 + 14 Ma (5) Reinbokkdalen (6) Bangenhuk 1739 + 49/-43 Ma (7) Intrumentberget 1737 + 46/-41 Ma The zircons indicate magmatic crystallization events. Determinations by Rb-Sr from six of the above gave c. 1650 Ma and Sm-Nd analysis indicated a significant crustal contribution to the granite magmas. They concluded that a homogeneous volcanic origin of the quartzofeldspathic gneisses can be discounted. Whether the foliation was Proterozoic or Caledonian is uncertain, but a Caledonian age was preferred. They suggested that the crystalline basement prior to Caledonian cover was subject to Paleoproterozoic or earlier orogenic deformation prior to the 1750 Ma granite intrusions. (vii) Larionov, Johansson, Teben'kov & Sirotkin (1995) dated the Eskolabreen Formation at c. 1770 and 1766Ma. U P b dating of zircons from a band of muscovite biotite gneiss within the Eskolabreen Formation in the Atomfjella Antiform at Stubendorffbreen gave c.1770Ma. Zircons from two samples of granitic gneiss pooled an upper intercept age of 1766+ 10Ma indicating the granite intrusion. A lower intercept age of 404 4- 8 Ma and a similar age by U - P b on titanite, i.e Early Devonian. (viii) Gee & Hellman (1996) using Pb-evaporation determinations of detrital zircons in the Smutsbreen (metasedimentary) Formation from two samples, each with 14 or 15 crystals analysed, obtained the following values: (1) 2 of 1190 Ma; 5 of 1560-1710 Ma; others ranging 990-2570 Ma and (2) 2 of 1200-1300Ma; 2 of 1650Ma, others ranging 1100-1880Ma. From the above they interpeted a major unconformity with a basement-cover relationship. (ix) Hellman, Gee, Johansson & Witt-Nilsson (1997) interpreted basement-cover relationships from three groups of determinations of rocks in one succession using Pb-evaporation methods on zircon crystals.

128

CHAPTER 7 The Instrumentbergetgranitic gneiss from five crystals obtained a mean of 1740+3Ma which, combined with data reported by Johansson et al. (1995) on the same rocks by conventional U Pb work with zircons, gave a mean of 1735 • 13 Ma. The Ingstadsegga Conglomerate resting on the granitic gneiss contained large clasts of similar composition, two samples of which gave respectively three zircon ages of 1739 • 2 Ma and 2 of 1738 • 5 Ma. The overlying quartzites of the Polhem Formation from one sample of seven grains all spanned 1743-2040 Ma; another, also of seven grains, gave the following 1317+7; 14984-6; 1510• 1868• 1971+7; 2712-1-9 and 2716 • 5 Ma. Other crystals gave 1452 • 5; 1999 • 27; 2572 4- 8 and 2805 • 20 Ma. These were all detrital grains sampling the sediment sources then exposed, and the lowest values give a maximum age for the Polhem Formation.

7.10

7.10.1

The Hecla Hock Complex: mid-Paleozoic structure and metamorphism Fold and nappe structure

The overall structure of Ny Friesland comprises fold systems with a dominant N N W - S S E strike with fold axes plunging north or south, generally 10 ~ or less. The fold pattern is modified by the batholiths which both truncate some and deflect other strata. Emplacement by stoping was followed by pushing aside the adjacent strata with attenuation after the igneous body had attained sufficient strength (Fig. 7.6). Otherwise no significant discordant structure has been confirmed except for unconformities at the lower boundary of the Planetfjella Group and the Polhem Formation, and the major thrust in Mosselhalvoya of the Planetfjella Group onto the Polhem Formation. The folds are thus remarkably homoaxial. The possibility remains that earlier discordant structures have been transpressed into concordant attitudes by extreme shear. The long established boundary below the Hinlopenstretet and Lomfjorden supergroups has been referred to as the Veteranen Line. (Harland e t al. 1992). East of it the quartzites, greywackes and carbonates of the Lomfjorden and Hinlopenstretet supergroups have behaved competently except for the shales, mainly Polarisbreen Group, which occur in tightly pinched synclines. The main fold pattern with the minor oblique faults stands out because of the contrasting lithologies of the various rock units. In the north the less competent rocks, especially the Polarisbreen Group rocks, have been tectonized and metamorphosed to chlorite facies which contradicts the view (e.g. M a n b y 1990) that the Veteranen Line delineates the metamorphic rocks. West of this Veteranen Line (VL) all the rocks have been metamorphosed and generally penetratively tectonised. The gross structures may be of recumbent folds probably with attenuated lower limbs. An altogether larger scale structure is the Atomfjella Arch or Ant• a major structure of variable plunge and exposing within it the Finnlandveggen Group rocks the oldest of which occur in the widest outcrops to the south. East of the Atomfjella axis strata dip eastwards, often steeply. To the west westward dips predominate, but not with the same regularity. Recumbent folds or nappes drape over the Arch with an apparent westward vergence. The observed recumbent fold hinges would be anticlines on this interpretation. Manby's cross-section illustrating easterly vergence (1990) depended on the strata in the nose of an eastward verging recumbent fold coinciding with his proposed faulted contact (Veteranen Line) over a distance of 50-100 km and also depended on correlating gneisses of the Harkerbreen Group with gneisses of Finnlandveggen Group, which hardly match the Fig. 7.6. Structural map of Ny Friesland (simplified with permission of Cambridge University Press from Harland et al. 1992). AA, Atomfjella Ant• BP, Raudfjellet Pluton; BFZ, Billefjorden Fault Zone; CP, Chydeninsbreen Pluton; LFZ; Lomfjorden Fault Zone; NP, Lomonesovfonna Pluton; VL, Veteranen Line.

NORTHEASTERN SPITSBERGEN above observations. In any case both large and small near-isoclinal folding is ubiquitous and clearly in need of more than the reconnaissance work on which these speculations are based. Chocolate-tablet boudinage in the flat limbs of the early nappes would be the result first of E - W extension during nappe emplacement and later of more intense N-S extension during transpression. The latter structure is dominant everywhere west of the VNL (Harland 1959; Harland et al. 1992). This N-S extension was first interpreted as escape tectonics responding to indentor compression (e.g. Harland & Bayly 1958; Harland 1959). When this seemed untenable the transpression concept was introduced Harland (1971). The initial collision tectonic phase to the east of the Veteranen Line was one of upright or westerly vergent folding and to the west was one of thrusting and nappe formation, producing a stack of nappes determined to a large extent by the competance contrast of the stratal pile. Because the sequence of strata crops out consistently through the pile of nappes, it is reasonable to suppose that the thrusting hardly disturbed the stratal sequence except in the extreme north. The nappe stack of Witt-Nilsson, Gee & Hellman (1997) below the Planefjella Group overthrust is thus, each on a thrust of the same name. Dirksodden Nappe = Sorbreen Formation Nappe Dirksodden Thrust Nordbreen Nappe

= Bangenhuken Complex = Vassfaret Formation intruded by Bangenhuk Formation Nordbreen Thrust

Rekvika Nappe

= Rittervatnet Formation Polhem Formation Instrumentberget-F15tan Formation Rekvika Thrust Smutsbreen Formation

Sinistral transpression then predominated causing the linear fabric and shear zones referred to below (7.10.2). The stack of thrusted strata was arched into the Atomfjella Antiform, which, because of its N-S continuity, suggests transpressional control. The extreme transpression that developed in a series of N-S shear zones and almost ubiquitous mineral lineation and boudinage, could have displaced sinistrally the rocks along the Veteranen Line some 100km north of the nappe fronts further west. Consequently attempts at E - W cross-sections (for example the structure shown in fig. 3 of Witt-Nilsson et al., with thick nappes and excised roots) may result from 200% E - W structural shortening, but with greater N-S shear. At a late stage in the sequence was the emplacement of the Caledonian batholiths which were also subject to some transpression.

7.10.2

Fabric and shear zones in the Stubendorffbreen Supergroup

The earliest schistose-gneissose textures are related to the largescale recumbent folds with foliation parallel to the bedding and containing quartz feldspathic segregations and then to transpression. Quartz and micas were ductile throughout relative to feldspars, pyroboles, and garnets. Feldspathite gneisses have been more intensely deformed than amphibolites. Porphyroblasts in gneisses exhibit rotation (sinistrally in plan). These contrasting competences have permitted widespread boudinage which is conspicuous with

129

MOSSELBUKTA

MURCHISONFJORDEN

WIJDEFJORDEN ~

HINLOPEN U

w ~ d~L~ WIJDEFJORDEN

. ~ O ~ L ~ , , L7

W4-1 " L2 / AUSTFJORDEN

"- ~

-

_N O ~ K A P P

~ ' ~ t ~ ' ~ T ~~ . ~ ~ r

LS"'" " L9"

VETERANEN M2 "

~I-,~OGEN

MI

E

CHYDENIUSBREEN

.....

E

NEWTONTOPPEN

_

I]~VAI~VAI

Fig. 7.7. Diagrammatic cross-sections across Ny Friesland from Harland's 1954 unpublished Sedgwick Prize Essay. Rock units L1 and L2 were then thought to be the oldest rocks, but are now generally regarded as belonging to the Harkerbreen Group. U, M, L refer to the three Hecla Hoek supergroups.

colour and competency contrast as between pale quartzite and black amphibolites. Boudins may be rectangular (then often rotated) or ductile when quartz, chlorite and/or calcite have grown at the points of rupture. Lesser contrasts have led to a less conspicuous foliation boudinage as indicated by a pervasive mineral lineation. The mineral lineation indicates extension, but cannot quantify the ratios. Boudinage typically suggests at least 1:2 ratios. The Rittervatnet Formation, with the meta-tilloid, contains relatively competent fish-shaped dolomitic marble megaclasts with axial ratios of 1:10. Less competent calc-marble megaclasts string out with ratios of 1:20 or 1:40 and still less competent matrix could thus have effected extensions of at least 1:100. In the schistose horizons a later folding phase is recorded in crenulation and kink zones associated with chloritization of biotite and hornblende. Concordant mylonite zones are found, especially in the Planetfjella Group and in the Harkerbreen Group adjacent to the Billefjorden Fault Zone.

7.10.3

The Billefjorden Fault Zone (BFZ)

The kinematic history of the BFZ is discussed in the next chapter and Chapter 16 where Devonian structures on the west are considered. Evidence of penetrative tectonization east of the main fault is part of the above considerations as they affect Harkerbreen rocks west of the Atomfjella Antiform (Fig. 7.7). In the south, Svenbreen and H6rbyebreen (and north to the west at Zeipeldalen) are exposed up to 3 km E - W of chlorite schists and gneisses bounded westwards by the Balliolbreen Fault and in the east by the Pyramiden Fault. This is named the Cambridgebreen Shear Zone. Pink grey gneisses with concordant chlorite schists appear to have retrograded from amphibolite to green schistfacies. Feldspars have been sericitized and quartz-rich beds tend to mylonitic texture. The chlorite-rich rocks indicate a late (post-Silurian) brittle shear phase, evident also in the (possibly rotated) island of Bjornesholmen off the coast of Austfjorden. Further north along the east of Wijdefjorden, Reinbokkdalen, Dirksodden and Gunvorbukta are exposed extensive green schist facies with retrogressive metamorphism as indicated above. At these localities and further north (e.g. Sorbreen) quartz-feldspathic rocks show fine-grained grey slate-like zones with feldspar megacrysts. These were shown by Manby in 1981 to be mylonites often with sharp margins to pink or grey gneisses. They utilize steep foliation in the folds. Sinistral rotation in the megacrysts is evident in the horizontal plane.

130

CHAPTER 7

Fig. 7.8. Three interpretive west-east sections across Ny Friesland. (a) Harland (1941). The Atomfjella antiform is shown with west verging nappes where A (in the centre) is the upper part of the Eskolabreen Formation and B the Smutsbreen Formation. C is now known to belong to the Harkerbreen Group as, indeed is also A in the east, seen at a distance in 1938 and colour correlated with A. (b) Johansson et al. (1995) shows the same Atomfjella antiform in Northern Ny Friesland with the new Instrumentberget unit between the Rittervatnet and Smutsbreen formations. The boundary between 'Middle Hecla Hoek' and the Planetfjella Group, which is argued here to be conformable, is shown as a fault across which there is no continuity. On the other hand the major unconformity claimed in this work between the Planetfjella Group and Sorbreen Fm is not distinguished here (reproduced with permission of Cambridge University Press). (e) Manby & Lyberis (1995) agree with this work in showing sinistral strike-slip zones at Austfjord and in the Eolusletta shear zone. They show recumbent folds verging eastwards in contrast to (a) and the Planetfjella Group is tectonically concordant with the Lomfjorden Supergroup. The uppermost formation of the former maps concordantly with the lowermost formation of the latter through a distance of nearly 130 kin, so the recumbent anticline is shown in (c) would be unlikely to maintain that juxtaposition for such a great distance (reproduced with permission of Blackwell Science).

7.10.4

PlanetfjeUa schists

West of the Veteranen Line (VL) are the Planetfjella Group gneisses and schists, with a conspicuous sinuous or crenulated foliation. There is also a N - S extension lineation with aligned feldspar megacrysts, and in addition retrogressive zones containing mylonites. These characteristics are explained as a shear zone with horizontal displacement. The zone coincides with favourable steep bedding attitudes so there is no obvious truncation of strata. The VL is simply a stratigraphic boundary between the Lomfjorden and Stubendorffbreen Supergroups. A large part of the three or more kilometres of Planetfjella strata are sheared and effect a significant displacement. This was referred to as the Eolusletta Shear Zone by Manby & Lyberis (1995) (Fig. 7.8) ~Vildadalen Formation. With present evidence of stratigraphic continuity between the Veteranen and Planetfjella Groups the Veteranen Line is not a major terrane boundary nor even a major discontinuity as indicated in the sections of Gee & Page (1994) and of Manby (1990, 1995).

The boundary between the Planetfjella and Harkerbreen groups may well be faulted, but essentially represents an unconformity between the Atomfjella Complex and a relatively unbroken succession- Planetfjella through Oslobreen groups. But it may not be a major unconformity, a great time hiatus, and certainly not a Proterozoic orogenic episode or terrane boundary.

7.10.5

Kinematic interpretation of transpressive shear in the Stubendorffbreen Supergroup

Stratigraphic evidence for considerable sinistral displacement, at least along the Billefjorden Fault Zone will be considered in Chapters 8 and 16. The structures and textures indicated above are consistent with such large scale displacement. Throughout the terrane west of the VL strong lineation fabrics and boudinage or augen gneisses are evident. At first these were thought to be the result of extreme squeezing between vice-like lithosphere blocks (Harland & Bayly 1958; Harland 1959) with lateral escape on a model later

NORTHEASTERN SPITSBERGEN termed indentor (Taponnier et al. 1982) and applied by Manby (1990) and Gee (1986), Ohta (1994) and Gee & Page (1994). On this basis the sheared rocks would result from squeezing out horizontally N and S. However, analysis of the structural evidence replaced this concept by the transpression hypothesis (Harland 1971) in which the whole of the Stubendorffbreeen terrane had suffered extreme oblique compression. It explains the ubiquitous, though not totally consistent, evidence of sinistral shear seen from above. It was suggested that transpression could be an intermediate phase between compression and transcurrence. The later transcurrence or strikeslip being most evident in the Cambridgebreen Shear Zone. Moreover, the shear movements were of at least two generations. The earlier (Silurian) transpressive shear with the main tectogenesis took place forming kyanite etc at depth. The later (Devonian) strike-slip, when much of the overburden had been removed, led by retrogressive metamorphism to chlorite. To anticipate, a case is made that transcurrence (or pure strike-slip continued through Early and Mid-Devonian time along this Cambridgebreen zone and that the Svalbardian (Late Devonian) tectonism was the result of a compressive component (i.e. transpression) leading to final docking of the two terranes. The extraneous evidence for the BFZ suggests displacement of hundreds of km so separating quite distinct terranes. The evidence within Ny Friesland also suggests sinistral displacement along the VL or just west of it, but not of the same, and certainly not of greater magnitude, perhaps only 50 to 100 km. This is because while structural and metamorphic facies are different across the VL the stratigraphy is consistent over at least 100 km of the line mapped in Ny Friesland (e.g. Harland & Wilson 1956; Wilson 1968; Wallis 1969; Harland et al. 1992; Harland 1995).

131

7.10.6 Metamorphism The principal effects of tectonism and deep burial are seen in the metamorphic facies throughout the western part of Ny Friesland. The geosynclinal pile was estimated roughly at 18 km before the Silurian tectogenesis which must have greatly increased the overburden so that even the Polarisbreen strata, originally only about 1 or 2 km from the ?top was sheared and preserved in chlorite facies, whereas the deepest staurolite-kyanite facies was plotted along the Atomfjella Antiform by Bayly (1957) in Figure 7.5b. If some of the thickness is the effect of stacked thrust sheets it hardly affects the calculation. The Caledonian contribution to deep burial would thereby be no less. During the progressive Ny Friesland Orogeny the most intense deformation, with stratal thickening in the west, would have been accompanied and followed by both transpressional attenuation and active erosion. The resulting deposits are not preserved, but may have thickened the overburden of the strata away from the orogenic axis to the east possibly promoting the Polarisbreen Group metamorphism. To the west, according to the strike-slip hypothesis developed in this volume, the site of the orogenic debris would be more than 200 km to the southwest. The preserved Devonian strike-slip along the Billefjorden Fault Zone retrograded amphibolites of the Harkerbreen Group to chlorite schists, the overburden by that time having been greatly reduced. As a preliminary to gravity surveys of Svalbard, Howells & Masson Smith (1977) measured the density of representative metamorphic rocks from Ny Friesland; but the survey, begun by F. J. Vine (CSE) was never completed.

Chapter 8 Northwestern Spitsbergen W. B R I A N

HARLAND

with a contribution with PAUL

A. D O U B L E D A Y

8.1 Cenozoic volcanic rocks of the Woodfjorden area, 133 8.1.1 Pleistocene volcanic rocks, 133 8.1.2 Miocene plateau lavas (Sorlifjellet formation), 134

8.4.6 Conclusion on Krossfjorden Group correlation and deformation, 144 8.4.7 The Richarddalen Complex, 145

8.2

8.5

Structure, 145

8.5.1 8.5.2 8.5.3 8.5.4 8.5.5 8.5.6 8.5.7 8.5.8

The Billefjorden Fault Zone (BFZ), 146 The Andr~e Land-Dickson Land terrane, 147 The Breibogen Fault (BBF), 148 Biskayerfonna-Holtedahlfonna Terrane (BHFT), 148 The Raudfjorden Fault (RFF), 150 Western Northwest Terrane, 150 The Pretender Lineament, 151 Timing of deformations, 151 Offshore geology (W.B.H. & P.A.D.), 152 The Yermak Plateau, 152 Sjubrebanken, 152 Danskoya Basin, 153 Norskebanken, 153

Mesozoic, Permian and Carboniferous cover, 134

8.2.1 Basal B0nsow Land Supergroup unconformity 134 and outliers, 134 8.2.2 Lamprophyres at Krosspynten, 135 8.3

Liefde Bay Supergroup, 135

8.3.1 Andr6e Land Group, 135 8.3.2 The Red Bay Group, 138 8.3.3 Siktefjellet Group, 140 8.4

The 'crystalline' rocks, 142

8.4.1 8.4.2 8.4.3 8.4.4 8.4.5

Early work, 142 Magmatic intrusions, 142 Migmatites and gneisses, 143 The Western Northwest Terrane formations, 144 The Biskayerfonna-Holtedahlfonna Horst formations, 144

Northwestern Spitsbergen is bounded by Billefjorden and Wijdefjorden in the east and by the coastline in the north and west round to the southwest by Kongsfjorden (Fig. 8.1). The southern boundary overlaps with the Central Basin (Chapter 4) and central western sector of Spitsbergen (Chapter 9) along Kongsfjorden and Sveabreen. At this boundary Devonian and older rocks are unconformably overlain, and finally obscured to the south, by the cover of Carboniferous through Paleogene strata. This sector contains Andr6e Land, Albert I Land, Haakon VII Land, James I Land and northern Dickson Land. It is deeply penetrated by fjords and largely covered by ice. Apart from Quaternary sediments and volcanics, Cenozoic plateau lavas and the overlying platform sequence (Carboniferous through Paleogene) to the south, the main consideration here is with Devonian sediments, mid-Paleozoic migmatites and granites, and Precambrian metasediments. The Northwestern sector is bounded and divided by faults. The eastern boundary is delineated by the Billefjorden Fault Zone (BFZ) and the southwestern boundary is the postulated Kongsfjorden Hansbreen Fault Zone (KHFZ). These faults separate the Central Province respectively from the Eastern and Western provinces. Two main N-S oriented faults divide the sector into three terranes: the Raudfjorden Fault (RFF), and the Breibogen Fault (BBF) (Fig. 8.1) as noted by Holtedahl (1914). The three terranes are introduced below. (1) The Andr6e Land-Dickson Land Terrane is a large area of Devonian strata bounded by the Breibogen Fault Zone and the Billefjorden Fault Zone. (2) The Biskayerfonna-Holtedahlfonna Terrane is a N-S belt bounded to the west by the Raudfjorden Fault and to the east by the Breibogen Fault. It is complex of a Precambrian horst and an Old Red Sandstone graben and has been referred to as the Liefdefjorden Terrane and Haakon VII Land Block. (3) The western northwest terrane, situated west of the Raudfjorden Fault Zone, largely comprises Albert I Land and is dominated by crystalline. Precambrian rocks that have suffered a major Caledonian tectonothermal event. This chapter addresses first the rock units (youngest first excepting the ubiquitous glacial and beach deposits) and then the structure of the region as a whole and of the individual terranes.

8.1

C e n o z o i c volcanic rocks o f the W o o d f j o r d e n area

The area around Woodfjorden contains small outcrops of Neogene and Pleistocene volcanic rocks. They form two distinct groups:

8.6

8.6.1 8.6.2 8.6.3 8.6.4

Neogene plateau lavas on the summits of the hills to east and west of Woodfjorden, and Pleistocene volcanic centres along or close to the Breibogen Fault zone. No other Neogene subaereal outcrops are known from Svalbard.

8.1.I

Pleistocene volcanic rocks

Three centres of Quaternary volcanic rocks occur along the trace of the Breibogen Fault zone, to the SE of Bockfjorden in eastern Haakon VII Land. The fault trends N N W - S S E and juxtaposes Precambrian marbles and gneiss to the west against Devonian sedimentary rocks in the east. The presence of hot springs and recent volcanic centres along the trace of the fault was originally noted by Hoel & Holtedahl (1911), Von Post (1912) and Hoel (1914), although further work was not undertaken until the 1960s (Gjelsvik 1963; Burov 1965; Semevskiy 1965). Recent work, from which the following review is collated, has mainly concentrated on detailed petrological and geochemical studies of the rocks (mantle xenoliths in particular) found within them, and their tectonic implications (Fumes, Pedersen & Maaloe 1986; Genshaft & Ilupin 1987; Amundsen, Griffin & O'Reilly 1987; Skjelkvgde et al. 1989; Tuchschmid & Spillmann 1992). Three volcanic centres are located at Sverrefjellet, Sigurdfjellet and Halvdanpiggen (Fig. 8.1). Field relationships. At Sverrefjeilet an eroded strato-volcano 3 km across with a relief of 506 m is exposed. Warm springs occur within 5 km along the line of the Breibogen Fault which separates Precambrian marbles to the west from Liefde Bay strata to the east. Reworked volcanic material forms marine tarraces along the edge of Bockfjorden. The volcano appears to be constructed of about 80% fragmented material including marble and about 20% lava and some rare tufts. All outcrops are shattered by frost action. The cone, into which a cirque has cut, is made largely of pyroclastic layers from 2 cm to several metres thick which contain lapilli and bombs. Lava flows consist of either pahoehoe flows up to 2 m thick, or pillowed flows up to 5 m thick which are commonly interbedded in sequences of up to 15 flows. The pillowed flows have formed high walls, consistent with an interpretation that they were erupted into water in proximity to a glacier wall. Sub-horizontal lava tubes have also been noted. All lavas contain a large proportion of xenoliths, typically constituting 15-20vo1% of the flow but up to 50vo1% at the base of flows. The xenoliths are up to 15 cm in diameter, and consist predominantly of Cr-diopside spinel lherzolites with minor occurrences of basaltic cumulates and granulites.

NORTHWESTERN SPITSBERGEN

BBF Breibogen Fault RFF Raudfjorden Fault

13 M611enfjorden 14 Sigurdfjellet

133

|

Fig. 8.1. Simplified map of NW Spitsbergen, based on various sources including Geological Map of Svalbard 1:500 000 Sheet G3 (Hjelle & Lauritzen 1982), Hjelle (1979) and Harland (1985). The black triangle, locality 6 (Krosspynten) denotes a number of Lamprophyre dykes of possible Carboniferous age.

134

CHAPTER 8

Signrdfjellet is situated 20 km south of Sverrefjellet. The volcanic centre forms a ridge 4.5km long, 200-250m wide and up to 250m high, with a maximum altitude of 1100 m. Eruptions at Sigurdfjellet would have involved fissure-like behaviour. Volcanic deposits comprise breccia, lapillistone, agglomerate, unlayered pyroclastic rocks, and rare lava flows over a topographically varied surface on both sides of the fault. The pyroclastic rocks are commonly ash deposits containing lapilli of vesicular basalt and volcanic bombs. The latter mainly have cores consisting of mantle xenoliths. Agglomerates include large clasts of Precambrian marble and gneiss, and Devonian sandstone. Late stage vents a few metres wide cut across earlier deposits, and contain unlayered pyroclastic rocks. Quaternary volcanic rocks in Halvdandalen occur at three separate localities within the valley. Unlike the localities described above, these lie 5 km east of the Breibogen Fault, over Devonian sedimentary rocks. At Halvdanpiggen there is a 250 m high volcanic neck, containing pyroclastic breccia and basalt. The former consists of 60-70% xenoliths and basaltic blocks with xenoliths within an altered glassy ash matrix. The basalts form multiple intrusions and also contain xenoliths composed of pyroxenite, spinel lherzolite and amphibole megacrysts. A 5m wide volcanic neck found at Olavstfirnet which again consists of basalt with xenoliths. This volcanic neck is cut by two later dykes. At Haraldknattane, three tuff-breccia vents are exposed, each containing xenoliths formed under conditions of high-pressure, and fragments of country rock. This volcanic edifice is also cut by two dykes. The rocks from all three volcanic centres have similar geochemistry, with a small range in major and trace element composition. They all lie close to the nepheline basanite/nepheline hawaiite compositional boundary, and were derived from primitive magmas, typical of intraplate alkaline volcanism. The xenoliths (for details see Furnes, Pedersen & Maaloe 1986; Amundsen, Griffin & O'Reilly 1987) are derived from mantle depths and indicate a rapid rise of the magma through the crust, probably without any residence time in crustal chambers. Amunden, Griffin & O'Reilly (1987) predicted depths of between 27 km and 50 km, wheras Tuchschmid & Spillmann (1992) thought they were probably derived from a depleted garnet-lherzolite mantle at depths greater than 60 km. There has been a general consensus amongst workers on these rocks that they erupted before and during the last major glacial period on Spitsbergen. The early work of Hoel & Holtedahl (1911) and Hoel (1914) considered the volcanoes to be of latest Quaternary age as they saw no evidence for glacial erosion. Semevskiy (1965) thought them to have formed between 4000 and 6500 years ago based on molluscan dating of uplifted marine terraces in Bockfjord that contained volcanic debris. An age of less than 0.7 Ma was proposed for Sverrefjellet and Sigurdfjellet by Halvorsen (1972) based on paleomagnetic dating. SkjelkvAle et al. (1989) evaluated the age of Sverrefjellet as lying between 0.1 Ma and 0.25 Ma based on available information on the timing of glacial maxima in the region. They thought Sigurdfjellet to be the same age, but Halvdandalen to be older due to the greater degree of weathering and its reversed paleomagnetic polarity (Halvorsen 1972). Analysis of the petrological and geochemical characteristics of the volcanic rocks, and particularly the mantle xenoliths, indicates that the crust beneath NW Spitsbergen is 27 km thick. At depths of 17-20km it consists of mafic granulite, below which there is a transition zone of granulites interlayered with pyroxenites and lherzolites. Below 27 km is mantle defined by the dominance of spinel lherzolite. A geotherm, constructed by Amundsen, Griffin & O'Reilly (1987), indicates temperatures significantly higher than those described in other intraplate alkaline provinces, This is consistent with an interpretation that the volcanism was due to the rise of a mantle plume beneath the area, associated with rejuvenation of the Yermak hotspot. 8.1.2

Miocene plateau lavas (Seidfjellet formation)

Exposures of fiat-lying lavas on the summits of some of the hills SE of Bockfjorden and in Andr~e Land were first documented by Hoel

& Holtedahl (1911). They have recently also been reported from a single locality in eastern Ny Friesland (see Chapter 7) (Tebenkov & Sirotkin 1990) which considerably extends the area which they may have originally covered. The several lava flows are taken as members of a single, once extensive unit named informally as the Sorlifjellet, corrected to Seidfjellet, formation after one of the principal mountains where it occurs. No strata are known above it. The flattopped mountains in Dickson Land, capped by lavas, are Tavlefjellet, Sorlifjellet (1036m) Okstindane, Vaktaren (1226m), Svartpiggen (1328m), Risefjella and Paleontologryggen (1200m). Some of these are shown in Figs 1.4. and 21.1. Volcanic lavas overlie Devonian sedimentary rocks at various scattered localities in Andr6e Land (3G Hjelle & Lauritzen 1982) and are interbedded with scoriaceous units in places (e.g., Tavlefjellet), together forming stacks of up to 15 flows. Tuchschmid & Spillmann (1992) described a 150 m thick succession of lava flows from Risefjella 3-5 m thick showing evidence of magma mixing and exhibiting columnar jointing. Elsewhere, Hoel & Holtedahl (1911) reported a 155m thick succession, and Burov & Zagruzina (1976) suggested a total thickness to be up to 275m. There have been no interbedded sedimentary rocks reported, nor any signs of internal erosion, suggesting that the volcanic pile was formed rapidly. The lavas are largely unaltered, and commonly vesicular. They appear to be relicts of extensive flows on a peneplane that has since been dissected. Petrological and geochemical analysis of lavas from Bockfjord area and Andr6e Land by Lussiaa-Berdov-Polue & Vidac (1973), Prestvik (1978) and Tuchschmid & Spillmann (1992) showed that they are largely enriched olivine tholeiites with some olivine basalts. Tuchschmid & Spillmann thought that the magmas probably originated from the upper, spinel-lherzolite dominated part of the mantle, at depths of less than 40-50 km. Phenocrysts (olivine and plagioclase) probably crystallized at low pressures in mid-crustal magma chambers, at depths of less than 15 km. The age of the lavas was widely regarded as postdating Early Cretaceous peneplanation. The first radiometric ages, by Burov & Zagruzina (1976), gave ages of 60 + 25 Ma and 22 + 10 Ma, but due to their large errors and variation were not widely accepted. The following year, Prestvik (1978) presented K-Ar ages of 11.5+ 1.2 Ma and 10.4 4- 1.1 Ma, late Mid-Miocene (Serravallian), for the lavas, which are currently the best data available and have not been questioned by later workers. It is possible that the centre of this igneous activity is related to the Yermak plateau (hot spot) all of which heralded the uplift of Spitsbergen and the Barents shelf especially at its northwest corner (see Chapter 21).

8.2

Mesozoic, Permian and Carboniferous cover

The somewhat artificial southern boundary of the sector in this chapter is taken at a stratigraphic level rather than a simple boundary. The overlying strata to the south are described as for the Central Basin in Chapter 4 and comprise the following: Nordenski61d Land Supergroup (with Triassic strata) Bfinsow Land Supergroup (Permian, Carboniferous and latest Devonian). It is indeed the cover sequence from Paleogene down to latest Devonian or Early Carboniferous strata.

8.2.1

Basal Biinsow Land Supergroup unconformity and outliers

The southern boundary of the pre-Carboniferous Terranes is essentially the unconformable cover sequence of the Central Basin. Being subhorizontal in a glaciated terrain of mountains and nunataks the cover strata appear as outliers to the north before the unconformity dips south below ice and then sea level where the

NORTHWESTERN SPITSBERGEN terrane is entirely of the cover sequence. The cover sequence is described in Chapter 4 and the boundary of this study area is thus a punctuated transition.

8.2.2

Lamprophyres at Krosspynten

Monchiquite (lamprophyre) dykes cut Keltiefjellet division strata (of the Wood Bay Formation). They are conspicuous rocks with large biotite crystals. This cross-cutting relationship indicates a post Early Devonian age which cannot be further constrained by direct stratigraphic relationships. However, an age of 309 + 5 M a by K Ar dating of biotites suggests a Moscovian (mid-Mississippian) emplacement (Gayer et al. 1966, item 76). They appear to be of a generation later than the lamprophyres associated with the late tectonic plutons of N y Friesland which may be early Devonian. The dykes are variable in structure, trending N-S, and thickness not exceeding 2 m. They occur immediately west of the Billefjorden Fault Zone and show some increasing shear structure, with calcite veining, towards it. From specimens CSE collected, 1957-9, J. C. Rucklidge, D. G. Gee with S. O. Agrell noted a fine-grained to glassy green rock (?analcite) with phenocrysts of biotite and xenoliths (some igneous some quartzitic) up to 12cm across and xenocrysts of biotite and pyroxene. Leucocratic ocelli, largely of calcite, suggested amygdaloidal texture. All in all it was concluded from a ghost olivine that a magma of olivinedolerite composition with xenoliths originating in the lower crust (or mantle) had been altered after emplacement by hydrothermal activity in an extensive regime. The titanaugite cores in zoned crystals were out of equilibrium in relation to the final crystallization.

8.3

Liefde Bay Supergroup

Nordenski61d (1866, 1867) included the Devonian strata of N o r t h Spitsbergen within his Hecla Hoek Formation as Red Beach Strata. However, in 1875 he used the name Liefde Bay Formation for these rocks to distinguish them from the Hecla Hoek to the east which he assumed to be Silurian (Kulling 1934, p. 166). Following Nathorst (in Suess 1988) the rocks (as outlined on his map in fig. 2.1) commonly referred to as Old Red Sandstone are thus properly named the Liefde Bay Supergroup. This is defined as comprising the Andr6e Land Group, the Red Bay Group and the Siktefjellet Group. The oldest of these three groups is neither typical 'Old Red' facies nor necessarily Devonian, hence the advantage of a distinct name for the whole package. With the exceptions of the Marietoppen Formation, north and south of Hornsund, and the Roedvika Formation of Bjornoya, the outcrop of the Liefde Bay Supergroup, or indeed Devonian rocks in Svalbard, is confined to northwestern Spitsbergen. The Liefde Bay Supergroup has an estimated maximum stratigraphic thickness of c. 8000 m which comprises three groups as follows. The Andr~e Land Group consists of Mid-Devonian Wijde Bay, and Grey Hoek formations and the Early Devonian Wood Bay Formation. The Mimer Valley Formation is in part a lateral equivalent in the southeast of the area to the above formations, although it continued into Late Devonian time. The group lies unconformably on the Red Bay Group. The Red Bay Group (2500 m) of Early Devonian age comprises the Ben Nevis, Framkelryggen, Andr~ebreen mainly sandstone formations, and the Rivieratoppen (conglomerate) Formation. This group unconformably overlies the Siktefjellet Group and overlaps onto metamorphic basement rocks. The Siktefjellet Group (4500 m + ) of ?late Silurian and/or Early Devonian age consists of the Albertbreen (sandstone) Formation the Lilljeborgfjellet (conglomerate) Formation and the Rabotpasset (conglomerate) Formation. Both conglomerates rest unconformably on metamorphic basement rocks. The Liefde Bay Supergroup facies are fluviatile and marginal marine molasse type deposits following the main phase of the Ny Friesland (Caledonian) Orogeny in Svalbard and the H a a k o n i a n

135

diastrophism. They were affected by earliest Devonian (Haakonian), Early Devonian (Monacobreen Phase) and Late Devonian (Svalbardian) tectonic activity separated by a time of relatively stable sedimentary environment. The Svalbardian movements closed the Caledonian episode. This completed the Basement structure. It was succeeded by the latest Devonian sediments that initiated the cover sequence and belong to the Billefjorden Group of the succeeding Btinsow Land Supergroup. The strata occupy a N-S-trending half-graben, bounded on the east by the Billefjorden Fault Zone, where the youngest rocks occur and the bottom is not seen, and to the west by a narrow horstgraben structure and then by basement rocks overlain unconformably, and repeated in a further zone by faulting. The net dip is thus eastwards. Figure 8.2 summarizes the stratigraphy and nomenclature of the Liefde Bay Supergroup. The names introduced in this work are from Friend et al. (1997), and explained briefly below.

Liefde Bay Supergp From Liefde Bay System of Nordenski61d (1875), as mapped (Nathorst in Suess 1888), the supergroup now refers to all the Old Red Sandstone rocks, of whatever facies, comprising three groups: Andr6e Land with Marietoppen Fro, Red Bay, and Siktefjellet. The Andr~ebreen (sandstone) Fm is redefined in two respects: (a) south of Liefdefjorden the large outcrop mapped as Siktefjellet sandstone by Gee & Moody-Stuart (1966) has been shown to be an extension of the Andr6ebreen Formation by Gjelsvik & Ilyes (1991); (b) further fieldwork by the Cambridge Group (Friend et al. 1997) described the original formation north of Wijdefjorden as comprising three members: Buchananhalvoya,

Princess Alicefjellet and Rabotdalen. Rivieratoppen (conglomerate)Fm. This name is introduced in place of Red Bay conglomerate partly because the name Red Bay is also used for the group that contains it and partly because until 1966 Red Bay Conglomerates included the conglomerates of the Siktefjellet Group as well. It has been redescribed as comprising the Wulffberget (marble conglomerate) Member and the Konglomeratodden Member (Friend et al. 1997). The name was mentioned in a similar sense, but not defined by Mokin & Kolesnick (1996). Albertbreen (sandstone) Fm. This is renamed from the Siktefjellet Sandstone Formation of Gee & Moody Stuart. Firstly, because Siktefjellet has been used for the group which includes this unit and secondly, because the Siktefjellet Sandstone as originally defined now appears to belong to two distinct groups- the northern (type) outcrop in Siktefjellet being of the original Siktefjellet Group and that south of Liefdefjorden belonging to the Red Bay Group being most nearly correlated with the Andr6ebreen Sandstone. Rabotpasset (conglomerate) Member was separated as an older more indurated basement breccia unit from the Lilleborgfjellet Formation (Friend et al. 1997). Friend et al. (1997) stratigraphy was based on field work in 1992 and earlier, and mostly north of Liefdefjorden. Since then the Red Bay Group strata south Liefdefjorden have been investigated by A. McCann working with the Norsk Polarinstitutt (pers. comm.) with further nomenclature which is introduced in Section 8.3.2 and is likely to be accepted by SKS. Observations at the southern margin of the main Devonian outcrop were made in Ekmanfjorden (Dineley 1960) and at Lykta (Birkenmajer 1965).

8.3.1

Andr~e Land Group

The Wijde Bay, Grey Hoek and Wood Bay formations were identified and described by Holtedahl (1914a, b, 1926). The Mimer Valley succession was first described by Vogt (1938, 1941) and by Friend (1961). For a time the latter were given group rank (Allen, Dineley & Friend 1967; Friend 1973 and Murashov & Mokin 1976, 1979), although Harland e t al. (1974) introduced the Andr6e Land Group which now contains the above units and the Mimer Valley strata reduced to formation and member ranks as shown in Fig. 8.2.

Mimer Valley Formation. Known from the detailed palaeontological research of Stensi6 1918a, who listed many beds with vertebrate remains, the unit was recognized and described by Vogt (1938, 1941) and Friend (1961) who systematized the named units.

136

CHAPTER 8

GROUP BILLEFJORDEN

NW ,

I

ANDRleE LAND

BBF

I

SE (Mimerdalen)

AGE

I

Tournaisian Famennian

HORBYEBREEN FM

ORUSTDALEN FM

SVALBARDIAN DIASTROPHISM

MIMER VALLEY WIJDE BAY FM (500-600 m) GREY

ANDREE

FM

LAND

(13001400 m)

3

Estheriahaugen Mbr (100 m) Eifelian

Gjelsvikfjellet Mbr (300 m)

Stj~rdalen Division

GROUP

n

D Frasnian

Givetian

FM

Forkdalen Mbr (630 m) Tavlefjellet Mbr (300 m)

HOEK

Plantekl~fta Mbr (100__m~_ __ Planteryggen Mbr(100 m) Fiskekl~fta Mbr (130 m.)_ __

D

Emsian

BBF

0

n,

(.9

WOOD

n,

U.I 13_ Z) CO

--..........~eltiefjellet, Lykta Division Skjoldkollen ~ ' ~ ~Vaktaren ~.~ (green) Mbr

BAY FM

Austfjerden (sandstone) Mbr

Kapp Kjeldsen Division

(2900+ m) O r s a ~

(SE)

Pragian

D l

M

Q3

y

BBF I

MONACOBREEN DIASTROPHISM LIJ D U_ ILl _1

(NW)

BEN NEVIS FM (900 m)

BBF

I

FR/ENKELRYGGEN FM (600-750 m) RED BAY GROUP

Buchananhalveya Mbr (700 m)(~qq ANDRleEBREEN . . . . . . . FM Princesse Alicefjellet Mbr (500 m) (1400 m)

Rabotdalen Mbr (200 m)

RIVIERATOPPEN FM (500-7(~ m)

SIKTE-

ALBERTBREEN FM

Wulffberget Mbr Konglomeratodden Mbr (3050-1400

Lower part of succession not exposed in the east

Lochkovian

?D

m) (~

?S

FJELLET

LILLJEBORGFJELLET FM (100-400 m)

GROUP RABOTPASSET FM

(?100 m) @

?S

SMEERENBURGIAN TECTOGENESIS KROSSFJORDEN GROUP

BASEMENT

Fig. 8.2. Liefde Bay Supergroup units with tectonic events and age estimates on the right.

Proterozoic

NORTHWESTERN SPITSBERGEN The formation occurs only in Dickson Land (the southeast of the northwest sector), the type section in Mimerdalen is at its eastern margin. Further west the units have not been systematically distinguished because facies vary considerably; although they are distinct from the (red coloured) Wood Bay Formation on which they rest. The faunal assemblage of the Mimer Valley Formation is rich in fish (Heterostraci, Acanthodii Arthrodira, Antiarchi, Crossopterygii and Actinopterygii), ostrocodes and conchostracans. The flora includes plant assemblages and many species of miospores (the Emsian/Eifelian Eximus and the Lochkovian Triangulatus assemblages of Allen (1967, 1973). Four members were distinguished. Planteklnfta Conglomerate Mbr, 100m is bed (m) of Stensi6 (1918a) and Plant Ravine Conglomerate (bed 9) of Vogt 1941. The member consists of pebble conglomerates with boulders up to 35 cm diam. consisting of grey (Devonian?) sandstone and some siltstone. The matrix is grey sandstone and beds of shale with ironstone concretions interbedded with plant-bearing dark green sandstones. Murashov & Mokin (1979) observed the conglomerate resting on different divisions of the Planteryggen (sandstone) Member. They also suggested that the units may be Early Carboniferous on the basis of lycopod remains. However, this review follows Allen (1967) in opining a Mid-Devonian (Givetian) or even early Frasnian (Late Devonian) age from palynomorphs. Planteryggen Sandstone Member, is Stensi6's bed (1) and Vogt's (1941) bed (8), who estimated a thickness of 400 m. It was named by Friend (1961) and consists of multicoloured sandstones and green shales. The uppermost 40 m are composed of red conglomerate with pebbles of quartzite, sandstone and siltstone. The basal sandstone is of sugary texture with large tree trunk fragments. Hoeg (1942), on the basis of plant remains suggested a mid- or Late Devonian age in contrast to Murashov & Mokin (1979) who preferred a later age, i.e. Famennian. Fiskeklofta Mbr, 115 to 145m contains Stensi6's Schiefer der Fischschlucht and other beds (1918a) and Vogt's (1941) beds 6 and 7. The sedimentary succession comprises 100m of green argillaceous sandstone and overlies brown and black shale. Flat ironstone concretions occur throughout and conformably overlie the Estheriahaugen Member. Westoll (1951), Halstead (1969) and Halstead-Tarlo (1973) considered the vertebrate fauna to be Late Givetian which is the strongest evidence for the age of any part of the formation. Vigran (1964), Allen (1967) and Murashov & Mokin (1979) discussed the age with less discriminating material. Estheriahaugen Mbr, 90-130 m in Stensi6's 5K1 to F2 and possibly his bed (e) (1918a) and includes Vogt's (1941) beds (1 5). The member is composed of light and yellowish grey polymictic, quartzitic sandstones interbedded with black shales and ironstone concretions. The lower part consists of shales. Cannel coals and pyrite nodules occur in the mudstones and upper sandstones. The lower contact with the Wood Bay Formation is c o n c o r d a n t whether conformable or tectonic. Spores suggest Givetian to Eifelian age. The lowest division (Vogt's bed 1?) has the Eximus spore assemblage indicating Emsian-Eifelian age. The Triangulatus spore assemblage follows Vogt's bed 1? (Allen 1967). Overall there is a contrast between the eastern and the western to northwestern development. It was formed in fresh water fluvial and lacustrine environments with cannel coal in Mimerdalen (Horn 1941) and oolitic ironstone (Friend pers. comm.) with periodic build-out of delta lobes towards deeper brackish water in the north west. Wijde Bay Formation, 500-600 m (Holtedahl 1914a; Friend 1961). At the top of the succession in Andr6e Land, 500-600 m of light coloured sandstones with siltstones and shales comprise the Wijde Bay Formation. Murashov & Mokin (1979) referred to it as a group with the Tage Nilsson Formation as its only constituent. The base is marked by the appearance of pale quartzitic sandstones interbedded with massive grey fossiliferous siltstone and black shales. Magnetite/hematite occur in joints. The light colour and increased proportions of sandstone distinguish the formation from that below. Fish faunas indicate a Late Mid-Devonian (Late Eifelian~Givetian) age (Nilsson 1941; Foyn & Heintz 1943; Murashov & Mokin 1979). The combined marine molluscan and non-marine fauna suggests a coastal, intertidal, partly brackish water environment. A build-out of sediments into the sea in a NNE direction is suggested. Grey Hoek Formation (c. 1000m). Holtedahl (1914a); Friend (1961), Friend et al. (1966); Murashov & Mokin (1979) originally gave the Grey Hoek unit group status and divided it into three formations which are reduced here to members:

137

Forkdalen Member Tavlefjellet Member and Gjelsvikfjellet Member Skamdalen Division Verdalen Division The Grey Hoek Formation succession consists of dark grey and black siltstones and sandy shales with intercalations of paler grey to green quartzites and dark shelly limestone bands. The lower part may be coarser and lighter in colour. The top is seen by a change of colour to the lighter sequence of the Wijde Bay Formation and the base is at the contrast with the, predominantly red, Wood Bay Formation. The stratigraphic thickness is difficult to determine because of strong folding and lack of marker horizons. Foyn & Heintz (1943) estimated 1000m. Worsley (1972) described the sequence in detail as follows: silty horizons have ripple tops with plant debris in the troughs. Desiccation cracks are abundant locally, as are slump structures and intraformational shales. Nucula sp. assemblages occur with both valves articulated. Massive coarse-grained sandstones have some mud-flake conglomerates at their base and become finer and better sorted upwards. Sandstones exhibit sole structures, sole marks, and cross-bedding, some horizons show slumping. The formation has yielded fish (Lunaspis, Homostius, Heterostius, Porolepis), bivalves, gastropods, ostractodes, trace fossils (Chondrites) and plants including charophytes. With the possible exception of the earlier part of the Gjelsvikfjellet Member (Emsian), fish and bivalve faunas indicate that the Grey Hoek Formation is Eifelian (Quensted 1926; Heintz 1937; Foyn & Heintz 1943; Orvig 1969; Murashov & Mokin 1979). Friend (1961) suggested formation in a marginal marine environment, whereas Worsley (1972) preferred fluvial action in a broad coastal swamp with shallow lagoons. Palaeocurrents (based on sole structures and crossbeddings) indicated predominant flow to the NE and NNE; but with some steeply folded strata there is some doubt. Forkdalen Mbr, 630m of grey and dark grey siltstones, mudstones and polymict sandstones with large carbonate nodules up to 1 m diam. Tavlefjellet Mbr, 300m. The upper part consists of dark grey to black calcareous mudstones with bands of silty carbonaceous nodules up to 0.5m diana. The lower 170m is dark grey to black shaly mudstones with 2 to 3 m bands of lighter calcareous siltstones/silty limestones with carbonate nodules up to 10m in diam. Gjelsvikfjellet Mbr, 60-200 m is formed of two divisions (beds) (members of Murashov & Mokin 1979) which contain almost identical fish assemblages suggesting coeval deposition of different facies. They reported that the upper Skamdalen division, of dark grey, micaceous, calcareous siltstones with black calcareous mudstones at the base rests unconformably on the Verdalen Beds in Andr~e Land and on red beds of the Stjordalen Beds of the Wood Bay Formation in north Dickson Land. The Verdalen division (0-100 m) was considered by Friend et al. (1966) to belong to the Wood Bay Formation. It consists of multicoloured silty limestones. Soft sediment sliding eastwards at Straumtangen on Wijdefjorden has been noted (Horowics 1992). Wood Bay Formation, 3000m, was defined by Holtedahl (1914a) and further described with its constituent parts by Friend (1961, 1965), Moody Stuart (1966) and Friend & Moody Stuart (1972) (Fig. 8.3). This is the main red bed unit of the Liefde Bay Supergroup and has a relatively uniform appearance with upward fining cyclic sandstone siltstone

Fig. 8.3. Faunal divisions and lithological members of the Wood Bay Formation (after Friend & Moody-Stuart 1972).

138

CHAPTER 8

facies and so is difficult to subdivide or to correlate divisions in the field. It is not therefore appropriate to refer to it as a group as did Murashov & Mokin (1979). Five distinct but impersistent facies occur within the dominant red siltstone lithology as illustrated in Fig. 8.3 and have been given member status (Friend et al. 1966). (i) The Verdalen (carbonate) Mbr has been already referred to. It consists of 30 to 40m of yellow and grey limestones and calcareous sandstone. On lithological grounds rather than on age it is reasonable to associate these strata with the Wood Bay Formation. (ii) The Skjoldkollen (carbonate) Mbr occurs locally in the north 100m above the top of the Kapp Kjeldsen faunal division. It is a 40 m thick unit, extending 8 km laterally, with 5 m thick green marlstone cyclothems. (if) The Vaktaren (green) Mbr (the 'Pale Beds' of Foyn & Heintz 1943) occurs at the top of the Kapp Kjeldsen division and extends 15 km laterally. (iv) The Orsabreen (green) Mbr is 600 m below the Vaktaren Member. Both these units are examples of colour-distinct units apparently due mainly to local reduction of iron. (v) The Austfjorden (sandstone) Mbr is a dominantly sandstone facies. It is non-cyclic, grey, green or yellow coloured and occurs mainly in the southeast, passing westwards into typical red beds with silty cyclothems. These five local facies variants do not add up to more than a minor part of the bulk of the formation. On the other hand three divisions, proposed by Foyn & Heintz (1943) and followed by Murashov & Mokin (1979) are faunally but not easily lithologically distinguishable. Though difficult to define precisely or to see at a glance they do constitute the whole of the formation and are more useful for general analysis of the stratigraphy. It is arguable that they should constitute the formal members of the formation if they are distinguished by observable biostratigraphic characters. According to the principle of rock, lithic or local units any observable characters whether colour, composition, elasticity or easily observable fossils may characterize a lithic unit if recognizable in the field. This question is left open. If they are members then the 'members' (i)-(v) above would become beds. Lamar & Douglass (1995), from detailed mapping southeast of Austfjorden, distinguished these three divisions lithologically in the Austfjorden sandstone facies, but did not demonstrate that their sedimentological criteria match the faunal divisions elsewhere. The Stjordalen Division is 400m thick in the north and thins to 50m southwards. The upper boundary being the sharp change to the grey-black beds of the Grey Hoek Formation, and locally the base of the Verdalen Member. The lower boundary is marked by the change from red mudstones and calcareous siltstones with pelletoid structure and has variable but distinct characteristics. The lower boundary is characterized by nectaspids, monaspids, osteostracans, arthrodirans and crossopterygians. The most probable age is Emsian (Murashov & Mokin 1979). The Keltiefjellet or Lykta division (600-900 m) generally comprises coarser grained sediments and thus not so red. It is rich in fossil fish with Doryaspis nathorsti, Arctolepis; but Gigantaspis; and small species of Doryaspis are absent. Fish and plants indicate a Pragian (Siegenian) age. The name Keltiefjellet was proposed by Foyn & Heintz (1943) and was renamed Lykta by Friend et al. (1966) on the basis of the current lithostratigraphic code. It was adapted by Murashov & Mokin (1979) as a formation. The Kapp Kjeldsen division (1000-1500 m) the top of which is marked by the 'pale beds', and the bottom by the change to the grey red rocks of the Ben Nevis Formation. This division is mainly composed of coarse-grained, greenish grey and yellow, cross-bedded and massive, micaceous sandstones and sandy siltstones with lenses and bands of grit and fine pebble conglomerates. The sands and sandy silts pass eastwards into the Austfjorden (sandstone) Mbr with an associated decrease in fossil fish and an increase in plant remains. The division is characterized by Gigantaspis, Arctaspis and small species of Doryaspis and near the top by Doryaspis nathorsti. These suggest a Pragian (Siegenian) age (Murashov & Mokin 1979) although ostracods and miospores indicate a wider age range, extending later to Emsian and Eifelian. The Sigurdfjellet Division was added on faunistic grounds at the base by Goujet (1984). Lamar & Douglass (1995) mapped an area SW of Austfjorden. They described the Wood Bay strata in the above three divisions (their formations) and showed that the Kapp Kjeldsen unit was dominated by channel deposits; Keltiefjellet by minor channel and major lev6e and floodplain sediment; and the Stjordalen without channel deposits. These characteristics may be local and all within Friend's (1965) Austfjorden (sandstone) Member. The original divisions were defined palaeontologically. It remains to be seen to

what extent the Wood Bay Formation is more conveniently divided by these three or four members with the facies variations as beds or vice versa. More significant perhaps is their isopach evidence of thinning of the Keltiefjellet unit from 1600 to 200 m towards Austfjorden, over a distance of little over 8 km. Crusiana are found throughout the t w o lower divisions and Lingula are only found in the Stjordalen division at one locality. Their presence suggests a marine influence. In the southwest (near the mountain Pretender) the Lykta division overlaps the Kapp Kjeldsen division to rest directly on Pre-Devonian metamorphic rocks, whereas to the northwest it rests conformably on the Kapp Kjeldsen division which in turn rests unconformably on the Red Bay strata. Friend & Moody Stuart (1972) suggested an intermontane flood plain environment for the Wood Bay Formation with marine incursions. In the southwest corner of the outcrop the red colour and carbonate concretions (calcretes also reported by Reed 1991) suggest a situation above the water table. It was argued to represent only part of the original basin, truncated by sinistral strike-slip along the Billefjorden Fault Zones (Harland 1969; Friend 1981). Three river systems have been distinguished in the formation and their interpretation is considered in Chapter 16. McCann (1996) demonstrated that the Wood Bay Formation unconformably oversteps in the southwest of the Biskayerfonna-Holtedahlfonna anticline in which Red Bay Group strata are folded (his Monacobreen Phase Diastrophism). A sedimentary transition had long been suggested first by Hoel (1914) south of Liefdefjorden, and at Sigurdfjellet and a third locality was added by Foyn & Heintz (1943) west of Bockfjorden. They wrote (p. 20) 'It is, however, only on Vonbreen (= Hoffnung Glacier) south of Sigurdfjellet that we can state with certainty that the Red Bay Series is normally covered by the Wood Bay Series'. Details of the critical strata were given in which at the base of the Kapp Kjeldsen Division are red sandstones resting conformably on greyish green sandstones with layers of quartz conglomerates at the top. The red beds bear distinctive pteraspids with some Doryaspis characters and other forms which could relate to Ben Nevis or Kapp Kjeldsen forms. The grey beds with fewer fossils include a small Pteraspis and Homaspis which are key elements in the Ben Nevis fauna. These critical units (referred to here as the Vonbreen sandstones) are east of the BBF. It thus seems that the Monacobreen folding may have been confined within the Biskayerfonna-Holtedahlfonna terrane and so reinforces the idea that the antiform may be the product of renewed transpression within that terrane (see Section 8.5.4).

8.3.2

The Red Bay Group ( N o r d e n s k i 6 1 d 1892; H o l t e d a h l 1914a)

This g r o u p is restricted at the surface to the west o f the half-graben (west o f the B r e i b o g e n F a u l t ) w h e r e it rests u n c o n f o r m a b l y o n either the Siktefjellet G r o u p or overlaps o n t o the m e t a m o r p h i c b a s e m e n t . T h e c o n g l o m e r a t e is its m o s t distinctive facies, a n d this was first r e c o r d e d by N o r d e n s k i 6 1 d (1892) in R a u d f j o r d e n a n d defined by H o l t e d a h l (1914a et seq.) (see Fig. 8.4). A. McCann (pers. comm.) has suggested that the conglomeratic sandstones, east of the Biskayerfonna-Holtedahlfonna metamorphic (Krossfjorden Group) horst, could be younger than the typical Ben Nevis Formation. Until the case has been demonstrated for an unconformable relationship above the Ben Nevis Formation they may provisionally be regarded as informal conglomeratic members of that formation. They are, west of the Breibogen Fault, the Fotkoilen sandstones and Lihallet conglomerates north of Liefdefjorden and Brottfjellet and Germaniabekken conglomerates south of Liefdefjorden. However, if significantly younger they might be members of a new formation between the Wood Bay and Ben Nevis formations. This however would appear to conflict with the evidence from the Vonbreen sandstones referred to above. The Ben Nevis Formation, 900 m (Kiaer 1916; Friend et al. 1966) consists of resistant grey-green, cross-bedded, polymict sandstones with grit, siltstone and argillite intercalations. A Late Lockhovian (Gedinnian) to Early Pragian (Siegenian) age has been determined from fish faunas (Heintz 1929; Vogt 1938; White 1956). The Fr~nkelryggen Formation, 600 750 m (Kiaer 1916; Friend 1961) of predominantly red beds is finer grained and more fissile than the Ben Nevis Formation. The red feldspathic sandstones and siltstones contain six intraclast conglomerate horizons rich in fish plates (Kiaer & Heintz 1935).

NORTHWESTERN SPITSBERGEN

139

Fig. 8.4. Geological map of the Raudfjorden/Liefdefjorden area, northwestern Spitsbergen, showing the distribution of the Siktefjellet and Red Bay groups (with permission of Cambridge University Press from Friend, Harland, Rogers, Shape & Thornley 1997).

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There is a welded tuff near the base (Murashov, Pchelina & Semebskiy 1983). An abundant fish fauna indicates a Lockhovian age (Blieck 1983). The Andr~ebreen (sandstone) Formation (Holtedahl 1914a; Friend 1961; Friend et al. 1997). The limitation of Friend's (1961) Formation by Murashov & Mokin (1979) to what is its top member is not followed here. Then formations are taken here as members of the original Andr6ebreen Formation. They stated that the lowest fossil horizon is located at the base of the Fr~enkelryggen Formation (apart from some plant remains) and the Andr+ebreen sandstone was thought to be fossil-free (Kiaer & Heintz 1935; Friend 1961; Blieck, Gonjet & Janvier 1987). However, Gjelsvik & Ilyes (1991) pointed out that the lowest P s a m m o s t e u s horizon is located on the Fr~enkelryggen ridge 550 m above sea level in a yellow-green sandstone of the Andr6ebreen Formation and well below the base of the Fr~enkelryggen Formation (Gee pers. comm.). This is significant because the 'Siktefjellet Sandstone' as mapped by Gee & Moody-Stuart (1966) south of Liefdefjorden, from paleontological evidence could be coeval and, with similar lithology should be considered a part of Andr6ebreen (sandstone) Formation. The matter is under investigation by Gjelsvik and Ilyes and their proposals regarding nomenclature are awaited. Friend et al. (1997) reinvestigated the Raudfjorden area and divided the formation north of Liefdefjorden into three members. Buchananhalvoya (sandstone) Mbr, 700 m (Friend et al. 1997) north of Liefdefjorden. This member is exposed throughout much of Buchananhalvoya as well as north of Andr~ebreen and is provisionally taken to include the main outcrops south of Liefdefjorden. It consists mainly of grey-green fine to medium-grained sandstone with occasional coarse sandstones and small pebbles. To the north the member interdigitates with the Princesse Alice Member and interbeds of conglomerates appear and thicken to the north. Thin (cm to dm) interbeds of dark-grey mudstones occur. The sandstones may be divided into sheet units up to several m thick with common ripple migration and cross-bedding. The sandstones contrast with those of the Siktefjellet Group below, not only because of a marked contrast in attitude of the strata, but also because of the greater abundance of potash feldspars and plagioclase in the Siktefjellet Group. The Buchananhalvoya sandstones carry little feldspar except near the Raudfjorden Fault at the head of Liefdefjorden. Princesse Alicefjellet (conglomerate) Mbr, 500 m (Murashov & Mokin 1979, Friend et al. 1997). This conglomerate contains clasts of red vein quartz, pink and green quartzite and quartz-mica schists It is a lateral equivalent of the Buchananhalvoya Member with which it interdigitates. It is interpreted as deposits of a river system alongside that forming the Buchanenhalvoya deposits to the south but depositing a uniform quartz-pebble breccia interbedded with pebbly sandstones. It is characteristically red but locally yellow or grey. The clasts rarely exceed 5 cm but occasionally reach 15 cm. Vein quartz and psammite constitute 60 90% of clasts with subordinate mica schists, gneiss and carbonate. However, the carbonate clast content increases towards the base near the marble rich Rivieratoppen Formation. The change in clast composition upwards suggests erosion by flash floods of mountainous terrane in which a marble cover was eroded into underlying quartzose strata. Rabotdalen (mudstone) Mbr, 200m. This member is poorly exposed and represents an interval between two conglomerate members (Gee & MoodyStuart 1966) and was recognized by Murashov & Mokin (1979) who estimated its thickness. In the stratigraphic scheme here it underlies the Princess Alice Member and overlies the Wulfberget (marble conglomerate) Member of the Rivieratoppen Formation. Friend et al. established a thickness of between 30 and a maximum of 100m. It does not crop out further south beneath the Buchananhalvoya Member. Known from float it is a fine dark grey, yellow weathering slabby mudstone which alternates with coarse siltsones. The facies appears to be similar to that occurring between conglomerate units within the Rivieratoppen conglomerates. A lake basin environment within the river systems is suggested. South of Liefdefjorden is the outcrop east of the metamorphic horst and west of the Breibogen Fault which was first included in the Siktefjellet Group by Gee & Moody-Stuart (1966) and then shown by Gjelsvik & Ilyes (1991) to be coeval with the Andr6ebreen Formation, but of distinctive facies. This member needs a distinct name. Provisionally it is included in the Buchananhalvoya Member. Gjelsvik & Ilyes (1991) noted that 'peloid'-carbonate conglomerate lenses within the sandstones contain a rich Lochkovian fossil fauna including four orders of fish (including Heterostraci, Placodermi, Acanthodii etc.) in addition to ostracodes, echinoderms, bivalves and gastropods. These strata thus contained the then earliest biostratigraphic evidence of Devonian age.

This marine component indicates a tidal basin mixing a variety of material of different origins. In the main Devonian trough, west of the horst and south of Liefdefjorden, McCann (pers. comm.) found that above the Wulffberget conglomerates the main body of the Red Bay Group is of two facies: the Smgtbreen (sandstone) and the Schivefjellet (conglomerate) members appear to make up his Wideroefjella Formation. This may be coeval with most of the three upper formations of the group. The Rivieratoppen (conglomerate) Formation (Friend et al. 1997). This formation represents the original Red Bay Conglomerate which name has been adopted for the group and which conglomerates also included those in the Siktefjellet Group. It is conspicuous in the eponymous pale coloured cliffs on both sides of Raudfjorden as seen on entering the fjord from the north. Exceptionally fine exposures are seen at Rivieratoppen and Konglomeratodden in Raudfjorden, in the islands of Liefdefjorden and on its north coast near the glacier and moraine of Erikbreen and in the cliffs of Wulffberget west of Hannabreen. Ilyes, Ohta & Guddingsmo (1995) reported heterostracans, both cyathaspidids and pteraspidids in the WulWoerget Member of the Rivieratoppen Formation in Hestekoholmen, the horse-shoe shaped island offshore Hannabreen in Liefdefjorden. Apart from the interest of this earliest fish record this confirms that the whole of the Red Bay Group is Early Devonian, and in this occurrence Lochkovian. Wulffberget (marble conglomerate) Mbr, 30-100m (Murashov & Mokin 1979; Friend et al. 1997) comprises red conglomerates containing large clasts of metamorphic basement rocks, notably marbles. Indeed the source rocks would often appear to correspond with the immediately underlying rocks. It exhibits a thick reddish colouring due to weathering of the marbles and the interstitial material. This member would seem to have local or southerly provenance from the distribution of marble in the basement. Neither granite nor migmatite clasts were observed (Harland 1961) except locally in the underlying member. Contacts with the basement may expose a transition from solid marble through marble with irregular veins of overlying sediment, through shattered marbles still retaining an original orientation, to irregular disoriented breccia with large and small clasts, to a coarse boulder breccia and upwards into a subrounded monomict conglomerate. Although the first appearance of the conglomerates suggests a massive hardly stratified rock, closer inspection reveals discrete units ranging from less than 1 m to about 10m in thickness. The distinction varies and can be due to changes in clast size, composition, general texture, matrix composition or a combination of the above. The typical Wulffberget lithology is of pebble- to boulder-grade clasts of subrounded, often monomict marble. The genesis of the conglomerate with such large boulders must have been local and often by cohesive bulk transport. Megaclasts up to 4 m have been observed and rafts of coherent structure seem to have been carried along. Transport is unlikely to have exceeded 2 or 3 km and the implication is of erosion from extensive and intermittent fault scarps. Manby & Lyberis (1992) figured Rivieratoppen with very large slabs and blocks seemingly cascading down the cliff face but within the conglomerate. Transport again must have been from a quite local scarp. Although the conglomerate constituents cannot have travelled far, they are extraordinarily widespread, not only through the length of the Biskayerfonna-Holtedahlfonna horst but also to the west of the Raudfjorden Fault in the islands of Kongsfjorden and the mainland to the north. This may be further evidence adduced for only one (Silurian) tectogenesis of the basement in that the upper marble formations had retained their superior stratigraphic position. Konglomeratodden (polymict conglomerate) Mbr, 180 m (Friend et al. 1997). Whereas the Wullfberget conglomerate often rests locally on Caledonian basement there is an underlying facies of polymict conglomerate seen at Konglomeratodden, the northern cliffs of Rivieratoppen, at Frankelryggen and overlying Siktefjellet grey sandstones (Albertbreen Formation) west of Siktefjellet. Both mass flow and fluvial genesis have been interpreted for the discrete sheets.

8.3.3

Siktefjellet Group

N o r d e n s k i 6 1 d (1892) first n o t e d c o n g l o m e r a t e s (in his H e c l a H o e k F o r m a t i o n ) in the n o r t h w e s t : H o l t e d a h l (1914, 1926) r e p o r t e d a n d t h e n set u p the O l d R e d S a n d s t o n e f o r m a t i o n s characterized by c o n g l o m e r a t e s a n d s a n d s t o n e s . T h e r e the m a t t e r rested (e.g. F o y n

NORTHWESTERN SPITSBERGEN & Heintz 1943; Friend 1961; Harland 1961) until Gee & MoodyStuart (1966) identified a significant unconformity within these rocks and distinguished an older group of sandstones and conglomerates as the Siktefjellet Group north of Liefdefjorden, especially at Siktefjellet. These older sandstones and conglomerates were more compacted and altered, less red, as well as being discordant with the overlying formations. The unconformity was held to represent a distinct diastrophic episode, which led Gee (1972) to name this 'Caledonian' event as Haakonian i.e. earlier than Svalbardian and later than Ny Friesland events in Svalbard. The age of the overlying Red Bay rocks are (earliest) Devonian, therefore the Siktefjellet rocks could be, in part at least, latest Silurian. Gee & Moody-Stuart (1966) defined the Siktefjellet Group as comprising two formations: the Siktefjellet sandstones (above) and the Lilijeborgfjellet conglomerate. In their map the conglomerate is confined to the outcrop north of Liefdefjorden but may occur on both sides of R a u d f j o r d e n - a convenient exposure being in Rabotdalen, of which a photograph by Holtedahl (1926, p. 1.2) confirms his inclusion of these conglomerates in his Red Bay Conglomerates. The sandstone described by Gee & Moody-Stuart (1966) is shown in a N-S-elongated outcrop south of Liefdefjorden as far as Bockfjorden. It is this outcrop which Gjelsvik & Ilyes (1991) suggested belongs to the Andr~ebreen Sandstone Formation of the Red Bay Group rather than to the Siktefjellet Group. They described these southern rocks as 'grey, grey green or occasionally yellow-green, tough and massive dm to m thick beds of fine to medium-grained sandstone', interpersed with up to 1 m thick lenses of quartzite chip conglomerates and frequent cross-bedding. The sandstones were compared in various aspects with those of the Siktefjellet outcrop. Mineralogically the northern facies had abundant potassium and plagioclase feldspars whereas to the south there was virtually no K-feldspar and little plagioclase. Lenses of peloid conglomerate or breccia in the southern rocks proved to be fossiliferous as noted above. The Siktefjellet Group was redescribed in three formations (Friend e t al. 1997) (Figs 8.4 & 8.5).

Albertbreen (sandstone) Formation (= Siktefjellet sandstone of Gee & Moody-Stuart 1966) north of Liefdefjorden as developed at the type locality

141

Siktefjellet and distinguished from Red Bay rocks by Gee & MoodyStuart (1966) and Gjelsvick & Ilyes (1992). The formation's outcrop area is limited between the Rabotdalen and Breibogen faults and to the south by Liefdefjorden and is therefore only exposed at Siktefjellet, where it is thickest, and then northward at H6geloftet and Fr~enkelryggen after which the Rivieratoppen conglomerate rests directly on the Lilljeborgfjellet conglomerate. The formation is of grey-green fine to coarse polymict feldspar-bearing sandstone with local intercalations of black shale, grit and quartz conglomerates generally fining upwards and cross-bedded. Gee & MoodyStuart estimated 1400m at Siktefjellet whereas Murashov & Mokin (1979) estimated 350m and suggested an age of Lochkovian from plant remains; but to which outcrop these observations refer is not clear. Sandstones or siltstone units may be 20 m thick, the sandstones often being cross-bedded and the siltstones ripple-cross-laminated. Black mudstones are interbedded with the siltstones. Plant fragments occur but are indeterminate. Pebbly quartz sandstones with pebbles up to 1 cm occur. The bulk of the formation is interpreted as fluviatile sands deposited by braided river flow, with the finer deposits forming in overbank areas (Friend et al. 1997). Lilljeborgfjellet (conglomerate) Formation, 100-140 m (Holtedahl 1914a; Gee & Moody-Stuart 1966). This pebble conglomerate contains boulders up to 25 cm diam. of basement rocks including migmatite and gneiss. These include a distinctive garnetiferous quartzo-feldspathic augen-gneiss the source of which is possibly the metamorphic terrane west of the Raudfjorden Fault. The conglomerates (e.g. at Puddingen) show mixed clast composition in contrast to the dominantly marble conglomerate of the Rivieratoppen conglomerates. Gjelsvik (1991) described the conglomerates in detail in terms of clast provenance. In addition to those lithologies which matched the underlying basement and were generally of angular character suggesting only local transport, he noted a minor component of well rounded (fartravelled) quartz porphyry. After detailed comparison with known quartz porphyries in Svalbard (including those at Nordauslandet, Hornsund and Ny Friesland) he ruled them out as probable sources for various reasons. The source of these quartz porphyries remains unknown. If the travelled terrane concept of Harland & Wright (1979) is considered, it may explain why the quartz porphyry clasts cannot be correlated with known quartz porphyries in Svalbard as these areas would not have been juxtaposed then, as they are now. Rabotpasset (conglomerate) Formation (Friend et al. 1997). This unit, included in the Lilleborgfjellet Conglomerate by Gee & Moody-Stuart, was first noted as a distinct lithology by Holtedahl (1914). It was separated, as

Fig. 8.5. Schematic section showing the relationships between the units of the Siktefjellet and Red Bay groups (with permission of Cambridge University Press from Friend et al. 1997).

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here by Friend et al., on the basis that at two localities (the main one is located at Rabotpasset) the rocks are more deformed, more indurated, veined and contain a much larger component of local basement gneiss etc. than the overlying unit. The induration has the effect of making the whole rock look like basement because the clasts and matrix may not at first be easily distinguished. Higher up quartzose and micaeous psammites increase in abundance. It was further suggested that this unit may be separated from the overlying conglomerate by a minor tectonic phase.

8.4 8.4.1

The 'crystalline' rocks Early work

'Crystalline' rocks (in this sense comprising igneous and metamorphic rocks and formed in a medium- to high-temperature environment) of this sector were perhaps first recorded by Scoresby in 1820 and described by Durocher (1840-1850). They distinguished foliated granite, gneiss and unfoliated coarse-grained granite with transitional schists. On Nordenski61d's 1863 expedition, Blomstrand (1864) i.a. described the metamorphic rocks further south in Albert I Land. Nathorst (in Suess 1888) mapped all the crystalline rocks of the northwest sector as Archean and only the southern and eastern part of the Albert I Land High as Hecla Hoek. Further records by Drasche in 1874, Bryant in 1905, and Schetelig in 1912 are of a more detailed petrological nature. These rocks were believed to be ancient until the Isachsen expeditions of 1909 and 1910 and the Hoel-Staxrud expedition of 1911 gave opportunity for Hoel and Holtedahl to show that the northern granites and migmatites post-dated the metasediments. Thus Holtedahl (1914a, b, 1926) claimed the complex as Caledonian. At that time it was generally assumed (as Holtedahl did in Svalbard, and indeed was assumed in Norway) that the Caledonian Orogen comprised mostly Early Paleozoic strata rather than Precambrian. Schenk (1937) described the structure and petrology in more detail. A more recent interpretation of all these rocks was presented by Gee & Hjelle (1966), updated by Ohta (1969) and Hjelle (1979) with the results from continuing Norsk Polarinstitutt fieldwork. The tectonisation and metamorphism of most of the rocks of the northwest were long regarded as of mid-Paleozoic age, it was not until isotopic studies that this could be confirmed. A midPaleozoic age was established for both metamorphism and granitic intrusion (Gayer et al. 1966) but there was insufficient discrimination to establish a petrogenetic time-sequence. Smeerenburgian is a name for this sequence of events whatever their age. North of Liefdefjorden, the Biskayerfonna Horst, was mapped by Gee, and the range of petrologic types encouraged further isotopic dating studies (Ohta, Dallmeyer & Peucat 1989; Peucat et al. 1989; Dallmeyer, Peucat & Ohta 1990). South of Liefdefjorden the principal studies of the older rocks have been by Preston (1959) and Gjelsvik (1979). A suspicion has continued that some elements ofproto-basement may be subsumed within the Caledonian complex. A migmatite complex (the Kollerbreen zone), north of inner Kongsfjorden, was considered as a possible pre-Riphean basement as by Krasil'shchikov (1973) and possibly by Abakumov (1976, 1979). Ravich (1979) examined the Kollerbreen Formation with Abakumov east of Krossfjorden with K-Ar age determinations (430Ma and 380Ma) and concluded (with Holtedahl 1914, Gee & Hjelle 1966, Harland 1978 and others) that they were migmatized (Caledonian) Krossfjorden Group Riphean strata. However the Abakumov interpretation has persisted (e.g. Krasil'shchikov, Abakumov et al. 1996). Balashov et al. (1996), applying Rb-Sr and single grain zircon datings, confirmed mainly Caledonian ages as well as at least one inherited zircon. From a structural point of view the time sequence (not necessarily synchronous throughout the region for each phase) can be established thus: sedimentation then tectonization with metamorphism-migmatization, magmatic intrusions, batholithic emplacement. Although there is just one complex, a Caledonian

one with an older core, the youngest intrusions probably derived from the earlier migmatic and magmatic material. The Precambrian protolith has been reconnoitred throughout the sector and, to anticipate the conclusion here, a succession of three formations distinguished to the west of the Raudfjorden Fault namely Generalfjella (top), Signehamna, and Nissenfjella (Gee & Hjelle 1966) were combined in the Krossfjorden Group (Abakumov 1976; Harland 1985). They are interpreted here as the product of Smeerenburgian (Caledonian) migmatization etc. Their palaeosomes may represent pre-Nissenfjellet Formation units. East of the Raudfjorden Fault and north of Liefdefjorden. Gee (in Harland 1985) distinguished a similar sequence with marbles at the top. Gjelsvik (1979) traced the same marbles south of Liefdefjorden and correlated them with the Generalfjella Formation. Some revisions of Gee's informal nomenclature is necessary because two names should give way to prior named units. It is reasonable to extend the group name to include all these formations but for discussion of correlation (which must be uncertain) to keep east and west formations named distinctly as in Fig. 8.6. The allochthonous Richarddalen Complex is demonstrably older and a well established unit of proto-basement.

8.4.2

Magmatic intrusions

Hjelle (1979) described granitic rocks under three headings: (3) posttectonic red granite (i.e. the Hornemantoppen Batholith); (2) grey granite dykes; (1) weakly foliated granitic rocks. He also remarked that basic dykes are not seen to cut the granite.

(3) The Hornemantoppen Batholith (150 km 2) crops out in a NNW elongate pattern within the migmatite area. The most conspicuous facies is a coarse- to medium-grained red granite. It is a nonfoliated mass of monzonite composition, mostly equigranular passing into porphyritic varieties. Potash and plagioclase feldspars occur equally (the K-feldspar in 2 cm crystals) then quartz (30-35%) and biotite (4-8%) with up to 2.6% chlorite. Plagioclase crystals (zoned from andesine cores to sodic oligoclase rims average An25_30) are often decomposed to sericite and zoisite. Accessories are titanite, apatite, pyrite and magnetite. There are rounded xenoliths (under 0.5cm) within the granites in addition to pink and red aplites and pegmatites. The 700 m erosion relief shows the granite neither to be a sill nor a laccolith. Adjacent foliations dip away from the granite and the granite always cuts across the migmatite gneissic structures with which it is always in contact. An age of the 414 • 10 Ma (Early Devonian or late Silurian) was noted by Hjelle (1979) (see Chapter 15). Balashov et al. (1996) from Rb-Sr and single grain zircon determinations confirmed that result with a value of 413 • 5 Ma (Early Devonian on the time scale in this work).

(2) Grey granite dykes. In some migmatite areas aplite and pegmatite sheets cut metasediments. Discordant sheets appear as an initial stage in the genesis of agmatitic migmatites. Other dykes up to 5 m thick which cut micaschists are folded with the country rock. Most dykes, however, cut both metasediments and migmatites with sharp boundaries and some are transitional to the grey foliated granites. Minor intrusions of a variety of types (Hjelle 1979) are extensive in northwest Spitsbergen. The only dates available are from Danskoya (Krasil'shchikov 1964; Krasil'shchikov, Krylov & Alpapyshev 1964) based on K-Ar ages, and recalculated with 1976 constants (but without analytical data) they indicate Early Ordovician to Early Devonian ages, i.e. 483-392Ma. A leucocratic granite from the flank of Fjortende Julibreen gave an Early Silurian K-Ar age of 430 Ma (Ravich 1979).

NORTHWESTERN SPITSBERGEN

Raudfjorden Fault

(WEST)

LIEFDE

Homemanntoppen (granite) Batholith (3)

BAY

Proterozoic KROSSFJO[~,DEN GROUP (2)(7) [Succession north of Liefdefjorden] (6) Lernereyane (marble) Fm, 1.2-1.5 km (7) Pteraspistoppen (marble) Mbr (6)

Generalfjella Fm (1) (marble with pelites)

0 r~ (.9

lower Krossfjorden Group strata

Erikbreen (pelite) Mbr (6) Hornbaekpollen (marble) Mbr (7)

Z Iii a r~

0

Signehamna Fm, 2-2.5 km (1)

(.9 n"

Nissenfjella Fm, >3 km (1)

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BAY

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GROUP

Montblanc Fm (6)

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Kollerbreen Fm, 6-10 km (2)

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CALEDONIANTECTONISM

13_

Migmatites invading

(EAST)

SUPERGROUP

Various granites

SMEERENBURGIAN (Paleozoic) TECTONO-THERMAL EVENT (9)

143

RICHARDDALEN COMPLEX (8) ? Caledonian (early Neoproterozoic-?Grenvillian and possibly Archean elements in high-pressure metamorphic complex)

thrust from the east

Fig. 8.6. Caledonian basement rocks in northwest Spitsbergen; numbers as follows: (1) Gee & Hjelle 1966; (2) Krossfjorden Group named by Abakumov (1976), defined by three formations of Gee & Hjelle (1966) by Harland (1978, 1985); Smeerenburgfjorden Complex named by Abakumov as underlying and older than Krossfjorden Group and including Kollerbreen and Waggonway formations, applied in this work to migmatic and magmatic products of Krossfjorden Group etc., as also suggested by Ravich (1979); (3) Hjelle (1979) mapped Hornemanntoppen Batholith; (5) Gjelsvik (1979) mapped Caledonian basement south of Liefdefjorden; (6) Gee's earlier survey north of Liefdefjorden with units reported in Harland (1985); (7) two of Gee's units renamed here because names were preoccupied, the Lerneroyane Formation replaces Gee's Liefdefjorden Group which was preoccupied in Suess (1888) and the Hornba~kpollen Mbr replaces Gee's Wulffberget marble-conglomerate, which was preoccupied by the Devonian (marble) conglomerate of Murashov & Mokin (1976); (8) Gee's Richarddalen Complex from his earlier survey referred to in Hjelle & Lauritzen (1982); (9) Smeerenburgian used in this work for migmatic and magmatic events in the western northwest sector.

(1) 'Weakly foliated grey granitic rocks' (of Hjelle 1979). Nearly all such granites are associated with migmatites and often with transitional as well as cross-cutting contacts. They may thus 'be considered as "mature" migmatites with a high metatect/metastar ratio' and tend to follow the migmatite rather than the metasediment attitudes. Several bodies occur within or adjacent to the migmatite area and are faintly foliated in places: (a) (b) (c) (d)

east of Krossfjorden-M611enfjorden - a monzo-granite; a dyke-like granite extending northwestwards from Sjettebreen; the granitoid at the middle and inner part of Magdalenefjorden (a granodiorite to quartz diorite); a plagioclase-porphyroblastic monzo-granite east of Smeerenburgfjorden extending southeastwards from Slaadebukta.

From these grey granitic rocks, Balashov et al. (1996) obtained zircon ages of 423 + 22 Ma (two grain analysis) and 461 + 42 Ma (three grain analysis) and 561 + 93 Ma. However, from one zircon grain in a grey granite an age of 952 Ma was interpreted as inherited from a deeper protolith. There is no conflict here with the Caledonian Orogeny and older ages from other inherited minerals in rocks within the granites and migmatites.

8.4.3

Migmatites and gneisses

Migmatites and gneisses, engulfing the older metamorphic rocks, are characteristic of northwestern Spitsbergen and are extensive throughout the older rocks there. In Albert I Land they range from just northeast of Kongsbreen to the north coast, and in the islands (Amsterdamoya and Danskoya). In H a a k o n VII Land they extend from just south of Liefdefjorden continuously in a wide belt to Holtedahlfonna. Schenk (1937) was the first to describe systematically the various gneiss to migmatite facies. Migmatites on this scale are not recorded east of the Breibogen Fault elsewhere in Spitsbergen, the only other area of such development is in Nordaustlandet which is probably Proterozoic. As these rocks occupy a central position in the metamorphic complexes and are flanked by recognizable metasediments, they were first thought to be the oldest rocks (e.g. Archean of Nathorst in contrast to his Hecla Hoek of the related metasediments). Since Holtedahl (1914a) recognized these rocks, and the related metamorphism and intrusions, as representing a post-Hecla Hoek Caledonian event, the first comprehensive accounts of the Northwestern Complex in Albert I Land were by Gee & Hjelle (1966), Hjelle & Ohta (1974) and Hjelle (1979) with detailed petrological studies by Hjelle (1966), Ohta (1969, 1978) and Ravich (1979).

144

CHAPTER 8

In H a a k o n VII L a n d further i n f o r m a t i o n has been provided by Gjelsvik (1979).

Layered gneisses.

In Albert I Land, Hjelle (1979) distinguished the 'layered gneiss' as an intermediate stage in the d e v e l o p m e n t of migmatites from mica schists (pelitic and psammitic). Typical compositions of layered gneisses in percentages are: Mafic layer, quartz 30, K-feldspar 5 plagioclase 35 (An2o-30), biotite 25, garnet+ cordierite + sillimanite 2; Felsic Layer, quartz 35, K-felspar 15, plagioclase 35 (Anl0-2o) biotite 10. Plagioclase porphyroblasts were a late development in the gneisses. However, composition varies considerably according to that of the protolith. The layered material may be mobilised and penetrated by granitic material concordanfly with the gneissosity. Dark micaceous lenses may be entirely enclosed by granitic material. A hornfelsed gneiss from upper C o n w a y b r e e n gave an early to mid-Silurian K - A r age of 430 (Ravich 1979).

Migmatites.

A further stage in the feldspathization and mobilization is seen in migmatite proper as discordant as well as concordant penetration of schists and gneisses by granitic material and with a total loss of original orientation. The inclusions in the migmatites are pelitic, psammitic, calcareous and amphibolitic. Pelitic types are most c o m m o n especially in the absence of marbles. Amphibolites and marbles tend to be associated. Larger xenoliths m a y have a hornfelsed skin and in some xenoliths, folds and b o u d i n a g e d layers are preserved especially in marble. The migmatites are not uniform in distribut i o n - larger bodies of m e t a m o r p h i c rocks do occur, and it is almost possible to discern a ghost stratigraphy. Overall, the bulk composition is that o f a granite or granodiorite. In H a a k o n VII Land, Gjelsvik (1979) reported that the granitic rocks are similar, in nearly all respects, to the grey granite or migmatite of the northwest corner o f Spitsbergen. He noted occurrences of Fe, Mg, Ca silicates near the a b u n d a n t marble bodies. Mineral assemblages indicated upper amphibolite facies. Retrograde metam o r p h i s m is evident in shear zones. Gjelsvik gave details of occurrences at different locations.

8.4.4

Western Northwestern Terrane formations

The Krossfjorden Group. Gee & Hjelle (1966) proposed a lithostratigraphy for the northwest metamorphic complex (west of the RFF) of three formations together comprising the Krossfjorden Group (Harland 1985). Abakumov (1976, 1979) had excluded a pre-Riphean basement to the Caledonian geosyncline which is an integral part of the lowest of the three formations. These divisions were based on the metasediments around Krossfjorden where the effects of metamorphism have been least severe. The less migmatized rocks were mapped approximately as Hecla Hoek rather than Archean by Nathorst (Suess 1888). The three formations are characterized by distinct lithological associations as follows. (3) The Generalfjella Formation, 2.5 km, is structurally the highest of the three divisions. It crops out in two areas: east of Krossfjorden from M611erfjorden to Blomstrandhalvoya, and west of Krossfjorden in Mitrahalvoya. The formation averages 2 km thick in the east but only the lowest 400 m are preserved in the west. Interbedded marble, pelite and psammite is the characteristic association. This formation is best known for the greyweathering Blomstrandhalvoya (marble) Member where the abortive marble mine/quarry was opened up but not exploited. Chlorite-spinel marbles were reported by Burcher-Nurminen (1981) (2) The Signehamna Formation, 2-2.5km, lies below and to the north of the Generalfjella Formation. Pelitic rocks are dominant with lesser psammites and up to 15 m thick units of conspicuous buff-brown quartzites. A few minor marble and amphibolite lenses were noted by Hjelle. Boundaries are transitional. (1) The Nissenfjella Formation, 2-3 km, lies below the Signehamna Formation and crops out on the west coast between Forstebreen and Sjettebreen. Gee & Hjelle (1966) suggested a thickness of 3 km, whereas Hjelle (1979)

calculated 2 km based on the southward plunge of the fold. The facies are pelites, with _<2m thick conformable amphibolites, psammite units and a variety of feldspathic lithologies, which pass northwards into gneisses and migmatites. In the north Ohta (1969) estimated the thickness of these much altered rocks in a deeper tectonic environment as 4-5 km thick.

8.4.5

The Biskayerfonna-Holtedahl Horst formations (Krossfjorden Group)

(a) North of Liefdefjorden Gee (1966) and Gee (in Harland 1985) described the following sequence north of Liefdefjorden partially renamed and re-ranked as follows (Fig. 8.6). (3) The Lerneroyane Formation, 1.2-1.5km (was Gee's Liefdefjorden Group and named for islands in Liefdefjorden) comprises three members the Pteraspistoppen (marble), the Erikbreen (pelite) and the Hornbaekpollen (marble), which was Gee's Wulffberget marble. (2) The Biskayerfonna Subgroup, 4.5-5km, comprises the same two formations as described by Gee. It is reduced to subgroup rank so that whole succession may be accommodated within the Krossfjorden Group. Biskayerhuken Formation, 3.5+ km, is formed mainly of pelites and is similar to the Signehamna Formation to the west. Montblanc Formation, 0.85-1.0km, is made of pelites, quartzites, foliated amphibolites (and gneiss), analogous to the Nissenfjella Formation to the west. These formations suffered upper amphibolite facies Barrovian metamorphism. Their correlation is speculative, and so justifies distinct nomenclature, although there is sufficient similarity to include them in the same (Krossfjorden) Group. Dallmeyer, Peucat & Ohta (1990) from Montblanc Formation by 4~ on amphibole obtained 429 and 437 Ma cooling ages. Muscovite and biotite recorded 402, 413 and 428 Ma (both by 4~ and Rb-Sr) interpreted as cooling through lower closure temperatures. These are interpreted here as mainly Silurian (417-443 Ma), characteristic of the main Caledonian tectogenesis in Spitsbergen ie. equivalent to the Ny Friesland Orogeny. (1) The Richarddalen Complex treated below (Section 8.4.7) is excluded from the Krossfjorden Group (b) South of Liefdefjorden. Gjelsvik (1979) described the types of m e t a m o r p h i c rocks south of Liefdefjorden without proposing a stratigraphic classification. Granitic rocks, migmatite and gneiss form the central part of the ridge and are flanked, and in part overlain, by a sequence of marbles and pelites. The marble does n o t always rest conformably on the gneiss, the b o u n d a r y being often tectonic. The pelites range from phyllite (green schist facies) to mica schist, and pass transitionally into the underlying gneiss. Psammites occur although quartzites are rare and occur in palaeosomes within the migmatites. The marbles are relatively pure calcitic with some interbedded dolomitic marbles. Most of the marbles are banded or bedded in layers from 1 m m to a few d m thick, some are fine-grained and others are coarse. Organic structures were not observed. Gjelsvik's m a p shows marble outcrops t h r o u g h o u t the horst as a regular envelope. Less than 1 k m o f strata are exposed in total to the south of Liefdefjorden and are disposed in an open antiform trending NNW-SSE. Gjelsvik suggested correlation of the marble with the Generalfjella F o r m a t i o n west of the Raudfjorden Fault. This is accepted here, and as the rocks also correlate north of Liefdefjorden the Lerneoyane F o r m a t i o n n a m e is extended southwards.

8.4.6

Conclusion on Krossfjorden Group correlation and deformation

The lithic scheme in Section 8.4.1 above, and applied here, preserves as far a possible the original names for describing the rocks. It does not assume identity o f formations between east and west but allows discussion of correlation.

NORTHWESTERN SPITSBERGEN

145

The marbles described by Gjelsvik are continuous with the Lerneroyane marbles. These are the highest stratigraphic units both east and west and crop out extensively. It has already been noted that the Red Bay (Rivieratoppen) conglomerates in both the east and west are also extensive and have formed largely from local marbles. It is therefore likely that the marble formations were once much thicker more widespread and were actively eroded in Early Devonian time. It is also significant that this general order of lithic types is observed throughout the northwest in spite of intense tectothermal activity. This coherent stratigraphic succession suggests that it was deformed, and suffered major thermal metamorphism only once in Caledonian times. It is therefore argued that it was not affected by significant pre-Caledonian tectogenesis and is thus not protobasement. The exception to the above is the allocthonous Richarddalen Complex which is certainly proto-basement and is discussed below.

8.4.7

The Richarddalen Complex

The Richarddalen Complex comprises a structurally complex group of varied metamorphic rocks contrasting with the Krossfjorden Group (Fig. 8.7). It was first described by Gee (1966), and Gee & Hjelle (1966). Most show polymetamorphic assemblages indicative of high P & T metamorphism with superimposed regression (Dallmeyer, Peucat & Ohta 1990). Eclogite, mylonitic, metabasic and ultrabasic rocks, various gneisses and marble comprise the principal rocks types. All boundaries to the groups are tectonic. It is imbricated with Biskayerfonna Subgroup rocks of the Krossfjorden Group. The Richarddalen rocks are not described in formations and so are strictly a c o m p l e x rather than a group. Several attempts have been made to obtain Precambrian ages. Recent values were obtained from U - P b on zircons in meta-granites and a gabbro (Peucat, Ohta, Gee & Bernard Griffiths 1989) and the 4~ and Rb-Sr results from Dallmeyer (1989). Peucat et al. (1989) suggested that these rocks were derived from reworking at 965 4-1 Ma of ancient crust 'as old as Archaean' (3234 + 43 Ma). In turn they were reworked by later tectogenesis with age determinations ranging from 661 to 402Ma (Ohta 1992) or 382Ma. It is therefore virtually certain that the Richarddalen Complex is not only Proterozoic (Neoproterozoic) basement but probably in part at least Archean. They commented: 'The high degree of discordancy of the zircon data and their typical magmatic habit strongly suggests that the lower-intercept age of 965 4- 1 Ma corresponds to the crystallisation of zircon from the magmas. The small amount of the ancient radiogenic lead indicates a component of Archean crustal reworking. The age of 3234 + 43 Ma can be the mean age of several populations of zircon of different ages; but strongly suggests derivation from Archaean crust' (Peucat et al. 1989, p. 278). Age determinations from eclogite and a 'late' intrusion (felsic neosome of agmatite) identify a later (the latest?) Proterozoic event. K-Ar methods on hornblende gave ages between 520 and 541 Ma (Gayer et al. 1966). Dallmeyer, Peucat & Ohta (1990) by 4~ on amphiboles obtained ages between 500 and 542 Ma, interpreted as cooling following the initial high pressure metamorphism. Rb-Sr ages recorded by muscovite and biotite are younger (410, 418, 420, 423, 430, 465 Ma). The latter are comparable to those of the interdigitated Biskayerfonna Subgroup results noted above, namely Silurian Ny Friesland Orogeny during which the thrusting would have emplaced the Richardalen Complex within the Krossfjorden Group. The earlier (Cambrian) values were not recorded in the Krossfjorden Group and the sequence of tectonism within the Richardalen Complex extended further back in time. Zircons from the ecologite dated by U-Pb method at 620 Ma suggest a magmatic origin and 620 4-2 Ma was suggested for the time of emplacement of the acidic magmas which are younger than the ecologite. The conflicting data nevertheless suggested a tectonothermal event from 660 through 620 to 540Ma (Peucat et al. 1989), i.e. Vendian to pre-Vendian. Whatever interpretation be preferred, a c. 965Ma magmatic event is established (i.e. proto-basement), with relict of an earlier

Fig. 8.7. Generalized geological map of Biskayerhalvoya, northwest Spitsbergen (after Ohta, Dallmeyer & Peucat 1989; Dallmeyer, Peucat & Ohta 1990 all based on survey by D. G. Gee).

proto-basement (somewhere) of Archean age, and a later (latest Proterozoic or Paleozoic) thermal event of unknown significance and finally Silurian tectonic emplacement with metamorphism. The ultrabasites and gabbros at Botnehaugen described by Abakumov (1983) probably belong to this complex.

8.5

Structure

Following the division of the northwestern sector outlined at the outset in this chapter and already applied stratigraphically, the following three terranes bounded by four faults are described, from east to the west (Fig. 8.8). (Ny Friesland terranes Chapter 7) 8.5.1 Billefjorden Fault Zone (BFZ) 8.5.2 Andr6e Land-Dickson Land Terrane (ADLT) 8.5.3 Breibogen Fault Zone (BBF) 8.5.4 Biskayerfonna-Holtedahlfonna Terrane (BHFT) 8.5.5 Raudfjorden Fault Zone (RFF) 8.5.6 Western Northwest Terrane (WNWT) 8.5.7 Kongsfjorden-Hansbreen Fault Zone (KHFZ) (Central west Spitsbergen terranes, Chapter 9)

146

CHAPTER 8

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probable mid-Devonian transcurrence, in Late Devonian (Svalbardian) transpression. After this, further movements have left little evidence of strike-slip, whereas rejuvenation of the zone occurred with mainly Carboniferous basin formation and Paleogene compression. For Devonian history this was the most active tectonic zone for which we have evidence in this sector. The central part of this zone was redescribed from new mapping by M c C a n n & Dallmann (1995), and detail of a small part by Lamar & Douglas (1995). However, the postulated sinistral strike-slip component has not been accepted by all. The matter is addressed at the end of the Devonian Chapter (16). Here only the structural evidence is outlined. Nearly all are agreed on a compressive component as seen in the deformed Devonian strata. The principal Balliolbreen fault, juxtaposing the Hecla Hoek and Devonian rocks, is seen north of Alandvatnet dipping 60 ~ to the east with Hecla Hoek metamorphics on the hanging wall. It has the appearance of a high-angle thrust (McWhae 1953; Harland 1959). Lamar, Reed & Douglass (1986) recorded some sinistral and some dextral reverse oblique slip and some horizontal dextral reverse slickensides on it. Figure 8.9 summarizes their map. The structure is truncated and covered unconformably by Tournaisian and possibly Late Famennian strata of the Billefjorden Group. However, M a n b y (1990) drew a cross section showing it as a normal dip-slip fault. To the west of the main fault are further thrust faults and folds verging westwards. Lamar et al. (1986) mapped these structures in part of Dickson Land (Fig. 8.9). Further north the exposures of the Andr6e Land Group are separated from the metamorphic rocks by Wijdefjorden which widens northwards. However the rocks are folded, occasionally thrust and exhibit cleavage. Carboniferous strata do not extend to the north

Fig. 8.8. Principal structural elements (mainly Devonian) of northwest Spitsbergen.

Sources applied here are Vogt (1928), Schenk (1937), McWhae (1953), Gee (1966), Gee & Hjelle (1966), Gee & Moody-Stuart (1966), Gee (1972), Burov & Semevskiy (1975), Hjelle (1979), Gjelsvik (1979), Ravich (1979), Harland (1985), Lamar, Reed & Douglass (1986), Lamar & Douglass (1995), Gjelsvik & llyes (1991), Thiedig & Manby (1992, 1994), Piepjohn & Thiedig (1992), Manby & Lyberis (1992), Friend et al. (1997); McCann & Dallmann (1995) and personal communications regarding earlier work by P. F. Friend and by A. McCann.

8.5.1

The Billefjorden Fault Zone (BFZ)

Long recognized as a major lineament running N N W SSE, the Billefjorden Fault Zone forms the trench occupied by Wijdefjorden and crosses a narrow isthmus with several sub-parallel faults to Billefjorden, which it crosses obliquely, and thence south under the Central Basin. The first description was by McWhae (1953). The fault separates the high-grade metamorphic Proterozoic Complex of the lower Hecla Hoek sequence in the west of Ny Friesland from the deformed but little altered Old Red Sandstones of Early to Late Devonian age to the west. The main movements were completed at least by Early Carboniferous time or earlier. They were related to the Svalbardian Folding first identified as Late Devonian by Vogt (1928). However, renewed activity along the fault zone allows it to be traced south into the Central Basin where Carboniferous, Permian, Triassic and Jurassic strata show both some syn-sedimentary movements and extensive later Paleogene tectonism. A comprehensive reconnaissance of the fault zone was made (Harland et al. 1974) which postulated a long history of intermittent sinistral transpression and transcurrence culminating, after

Fig. 8.9. Map of central west Dickson Land, simplified from Lamar, Reed & Douglass (1986).

NORTHWESTERN SPITSBERGEN where the pre-Carboniferous age of the deformation cannot be confirmed, but there is a continuity and similarity with the demonstrable pre-Carboniferous structures in the south. The strike-slip structural component in transpression is generally far less evident than its dip-slip (compressive) component. This is the reason why transpression generally went so long unrecognized even though it was logically necessary as a consequence of the interplay of lithosphere motions. Moreover, it is not often recognized that transpression may be partitioned into strike-slip and dip-slip components (e.g. Harland 1971; Teyssier, Kleinspehn & Pershing 1995). The most obvious structural evidence for transpression is in western Ny Friesland, but that is mainly Silurian including the strike-slip mylonitic components which did not develop in Devonian strata to the west. The evidence for continued Devonian strike-slip lies partly in the sedimentological configuration and in stratigraphic contrasts across the Billefjorden Fault Zone. The main structure resulting from the strike-slip component is seen in the 2-3 km Cambridgebreen Shear Zone of low grade chloritic facies immediately to the east of the main fault. This was formed under much lower tectonic load than was the Silurian deformation. It is arguable that strike-slip without transpression was active through late Early and Mid-Devonian time, causing much of the necessary translation of at least 200 km (say 300 km), but that in the final Late Devonian stage the (Svalbardian) folding resulted in a final transition again from strike-slip via transpression and (on locking) to compression. The transpressive structures in the Andr6e Land Group rocks in Dickson Land are consistent with, but not uniquely constrained from, the pattern of fold and thrust orientations which are often not orthogonal. Similarly further north in Andrbe Land, though further removed from the fault zone, are non parallel (en 6chelon) fold axes consistent with sinistral transpression (e.g. from structural data in Piepjohn & Thiedig 1994). Evident compressive structures cannot rule out an oblique component which may be hidden in strike-slip. The evidence of strike-slip is in the Cambridgebreen Shear Zone. The seismic E - W profile just south of this study area shows Hecla Hoek basement with less than 2 km of cover (Late Paleozoic) to the east of the BFZ against which a wedge 10-11 km thick of mostly Devonian strata abuts the vertical fault and thins westward (Faleide et al. 1991). It would be difficult to explain this crosssection other than by Late Devonian strike-slip.

8.5.2

Following Vogrs (1928) identification of the Svalbardian Folding in the east of the terrane, Schenk (1937) described the whole structure in outline. The next structural study was by Friend in the early fifties in the course of his stratigraphic and sedimentological investigations. These were not published and his block diagram appears here as Fig. 16.8 depicting the structure of the eastern belt. Burov & Semevskiy (1979) gave the first systematic description of the structure of the whole Devonian outcrop; but only in outline. More detailed observations were made by Piepjohn (Piepjohn & Thiedig 1992) on the structures as seen from Woodfjorden. The following account draws on these sources and is interpreted from the author's own visits to most areas over many years. The rocks deformed in this terrane belong almost entirely to the Andr6e Land Group (Early Devonian to early Late Devonian) and the age of folding is at least pre-Carboniferous and therefore late Devonian. The intensity of deformation diminishes westwards so that the most intense folding is seen just west of the Billefjorden Fault Zone. The strata east of the Breibogen Fault (as seen in Reinsdyrflya and west of Bockfjorden) are generally flatlying with minor disturbance. The main deformation is thus seen in Andr6e Land and Dickson Land which probably owe their mountainous nature to the folding which is intense in places. Schenk (1937) showed the above distinction in his cross section of Northwest Spitsbergen with the strata east of the Breibogen Fault dipping gently eastwards and the main body of Andr6e Land strongly folded with upright folds. Burov & Semevskiy divided the area by a main anticlinal axis running due south from Gr~huken, the northern tip of Andr6e Land, nearly to Dickson Land. They distinguished Dickson Land as largely occupied by their Wijdefjorden Fault Zone, which also extends on the northeast coast of Andr6e Land. The northwest coast of Andr6e Land was bounded by their Woodfjorden Fault Zone running N E parallel to the shore. A synclinal axis to the west parallels the anticlinal axis. As with many Russian tectonic interpretations their map is dominated by block faulting. Piepjohn & Thiedig (1992) described some folds in more detail. A cross section (Fig. 8.11) from the main Andr6e Land Anticline westwards shows the style of upright folding in the north deforming Grey Hoek strata. On the eastern flank of the anticline the minor fold axes (with one exception) plunge S to SSW, i.e. oblique to the N N W trend of the BFZ. This supports the impression of early Cambridge parties that (en 6chelon) oblique folding, consistent with sinistral strike-slip in northern Andr6e Land. Only one plotted exception is parallel to the fault zone. To the west of Andr~e Land the folds are somewhat asymmetric and verge westwards which is consistent with the manifest westward thrusting seen further south in Dickson Land. Burov & Semevskiy described three linear belts of intense folding and faulting. Their parallelism with the principal bounding faults and lack of deformation in the intervening areas suggested rejuvenation of activity along buried faults. (i) Along the eastern boundary of the terrane is a zone of deformed Devonian rocks up to 4 k m wide to the west of the Balliolbreen Fault of the (BFZ). This zone and Hecla Hoek

The Andr6e Land-Dickson Land Terrane

This terrane, clearly defined between the BBF and the BFZ, is the exposed repository of Devonian sediments and has generally been referred to as a graben. However, the Billefjorden Fault Zone (BFZ) which defines its eastern margin appears to truncate a once more extensive basin and has a significant post-Liefde Bay Supergroup history. Moreover, there is no clear western boundary fault system to the west.

ALBERT

I LAND

147

HIGH

BISKAYERFONNA

~-r~

HOLTEDAHL, FONNA J BLOCK

I I I

,~,~ 'i

ANDRI~E

LAND

BASIN

Raudfjorden Fault Breibogen Faulll Woodfjorden Andr6e Land Syncline Anticline Hannabreen Fault I SiktefjelletGroup I t ~. RedBay ~, ; / GreyHoekFm Woodfjorden X '~r,... . . . ~, , / ' l . "~'~'~s-'" ~*J. ' ~ " , . L ' ~~. X Group ~

"~

"J Basement

\

+ + + , + ", ,s'.-\ " % / / + + + +l+ + / Basement

4-

Fig. 8.10. Generalized cross-section across northwest Spitsbergen, from the Albert I Land High to the Andr6e Land Basin (modified from Hjelle & Lauritzen 1982).

OL

0

I

5

I

10

115

21

\!

~.~..:J.. ~ bfWoodBayFm ~ i ?unknown

depth to basement?

/Wijde Bay Fm / ijdefjor den

148

CHAPTER 8 Folding, of course, occurred before peneplanation a n d extrusion of Cenozoic lavas. / !/

//

WEST

!

1 km

Transition to the Andree Land Anticline HAST

|

ilryj3 Fig. 8.11. Structural profile across the Andr6e Land anticline between GrAhuken and Mushamna, simplified from Piepjohn & Thiedig (1992, fig. 5). deformation east of the fault constitute the Billefjorden Fault Zone. In northern Dickson Land it is 1.5-4kin wide and termed the Gr5kammen Graben (Burov & Semeviskiy 1979) (Fig. 8.8). Burov, Semevskiy et al. (1996), in describing the structure of south eastern Andr6e Land and especially the faults, referred to 'the eastern boundary zone of faults' (of Livshits 1974) with a total displacement along this zone of 3 - 4 k m . Within the zone the authors recognized a subzone of 'main strike-slip faults' on the east, and a subzone of 'shears and linear folds'. The boundary between the subzones is marked by a narrow (2-2.5km) Gr~kammen Graben. Its eastern margin encompasses a vertical zone of breccia (30-70m wide) cemented with quartz and calcite. The authors related the monchiquite dykes to the faults within the subzone. (ii) The Gronhorgdalen Belt can be traced for about 60 km with a maximum width of about 5 km (Fig. 8.8). The Wood Bay Formation is seen in a series of steeper dipping western limbs of the anticlines which are truncated and overstepped by Carboniferous rocks in the south. The fold axes are parallel to the belt or cut across it in a NNE-SSW direction. Plunges are commonly steep (60 ~ and to the south. Burov & Semevskiy (1979) described the Vestfjorden synclinal immediately to the east of the Gronhorgdalen Belt. (iii) The Orsabreen Belt appears to be a system of symmetric anticlines. Relatively discontinuous deformation can be traced south for 20 km with a width of 1 km. Similar trends and relationships to the Gronhorgdalen Belt are found, although on a smaller scale; but it is cut by a major longitudinal fault with a downthrow of 400-500 m to the west. This fault also affects Carboniferous and Permian rocks to the south with a throw of least 400 m. Further north, strong folding affects the Andr6e Land Group resulting in the broad Andr~e Land Anticline and Woodfjorden Syncline (Figs. 8.8 & 8.10). The Andr6e Land Anticline may be a continuation of the Grenhorgdalen Belt although much broader or, according to Burov & Semevskiy (1979), it could curve into the BFZ near Vestfjorden. The anticline culminates around Kartdalen and its steeper eastern limb (20-25 ~ is referred to as the East Andr6e Land Monocline (Burov & Semevskiy 1979). Small NNE-SSW and E - W trending folds are found in this area. The Woodfjorden syncline (Burov & Semevskiy's Andr6e Land syncline) exposes a number of large and small scale chevron type folds with steep dips and steeper dipping western limbs. They reported that the main syncline dies out to the south, while in the north the axis of the synclinorium is coincident with their Prinstoppen Graben Anticline. The small scale folds plunge north and south, possibly resulting from E - W cross-folding. The folds as a whole indicate that the maximum principal stress was WNW-ESE, consistent with sinistral transpression. Mention should be made of the hypothesis of Chorowics (1992) who proposed that, because some soft sediment deformation identified implies an eastward motion, the basin floor sloped to the east and the sliding sediments left areas of extension in the west with compression, against the Ny Friesland block in the east. It is not clear to what extend he proposed this as a supplementary or as an adequate process to account for the Svalbardian folding.

8.5.3

The Breibogen Fault (BBF)

The BBF parallels the Raudfjorden Fault and similarly is not seen to cut Wood Bay strata south of Holtedahlfonna. Therefore, the principal movements had probably ceased before deposition of the Andr~e Land Group. That is the time of the Monacobreen Diastrophism. The fault is straight and vertical and its trace is distinct across country visible by the contrast of red Wood Bay strata on the east and dark metamorphics on the west. In the cliff at Breibogen the red beds are poorly exposed, but on the other side narrow shear zones with mylonites extend at least 500m to the west and are more concentrated near the fault. A coarse sedimentary Wood Bay Formation breccia occupies much of the shore on the east side, again indicating some contemporaneous activity of the fault. Further east these strata exhibit a gently eastward-dipping regional homocline (5 ~ although dips steepen near the eastward dipping normal fault. Sporadic conglomerates in the Wood Bay strata thicken towards the fault and suggest some activity during deposition. On Fotkollen, immediately to the west of the fault (and NE of Siktefjellet) is a 150 m wide zone of shattered sandstone much coarser than the Wood Bay Formation and suggestive of Red Bay sandstone facies. West of this zone is another zone of shattered pelitic and psammitic schists. Fragments show a marked lineation; but in situ orientation was not seen. Still further west typical psammitic (to pelitic) schists occur. About 2 km to the south, on Siktefjellet, the Wood Bay Formation strata appear to be faulted directly against dense (indurated) Siktefjellet Group quartzites. Some loose blocks show mylonitic texture which is itself brecciated but, as above, in situ structures were not easily accessible. Near the north shore of Liefdefjorden, feature and float mapping suggested that at least two faults juxtapose metamorphic rocks and Siktefjellet Group rocks. With an inferred 2 km offset to the east, the BBF resumes its course from Liefdefjorden to Bockfjorden, separating Wood Bay Formation to the east from the Andr+ebreen Formation to the west. South of Bockfjorden the zone of Quaternary volcanic activity coincides with the BBF. The fault then extends southwards to Holtedahlfonna south of which the Wood Bay Formation, overlain by Late Mississippian strata, appears to cross the line without deflection (Hjelle & Lauritzen 1982, map 3G). Still further south a conceivable continuation in line appears as a fault throwing Triassic rocks down against Carboniferous and Permian - a fault which curves round west of Bohemannflya and Erdmannflya. However, excepting this last deflection in much younger rocks, which may not be related, the fault trace along the Liefdefjorden Belt is so straight as to require a strike-slip origin.

8.5.4

Biskayerfonna-Holtedahlfonna Terrane (BHFT)

This terrane, bounded by two straight and parallel faults (BBF & RFF), is a N N W - S S E strip exposed for 100 km N-S and 10-17 km wide. There are two distinct elements subparallel to the boundaries. (i) a N-S horst of metamorphic rocks of the Krossfjorden Group, capped by marbles and with a core of migmatite, pelitic schist and marbles. This is the Biskayerfonna-Holtedahlfonna Horst; or in this context 'the horst'. (ii) To each side, mainly on the west, are elongated troughs or basins of Red Bay Group (recently mapped by A. McCann, pers. comm.) and some Siktefjellet Group strata. To anticipate, this terrane is interpreted as having suffered intense main Silurian Caledonian tectogenesis with thermal mobilization in which the fault systems developed possibly out of a sinistral transpressive orogeny and between which the latest Silurian early Devonian sedimentation was controlled by continued alternating transtension and transpression. Fault scarps are interpreted

NORTHWESTERN SPITSBERGEN

149

as having provided much of the sediment, the transpression inducing the deformation. These extended Haakonian phase movements ceased during late Red Bay Group time (Friend et al. 1997). The two elements are separated by the oblique Hannabreen Fault which runs NW-SE from midway in the terrane to the north to join the Breibogen Fault south of Liefdefjorden at Bockfjorden.

Because the Hannabreen fault in the north appears with downthrow to the west and in the south with downthrow to the east, it has been suggested as a scissors fault. However it seems more likely to be a strike-slip fault not evident where the scissors' hinge would be, because it was not active after deposition of the overlying upper Red Bay Group strata.

(a) North of Liefdefjorden. To the west is the Raudfjorden Basin, which has long been seen as a synclinal structure occupied (except in the south) entirely by conglomerates, breccias and sandstones of the Red Bay Group. Most of the area is obscured by Raudfjorden itself (Red Bay), by western Liefdefjorden and the glaciers between them. In the south (north of Liefdefjorden) the Red Bay conglomerates rest unconformably on basement composed of marbles and pelites (Lerneroyane Formation). To the east, and occupying the high ground from Biskayerhuken in the north to Siktefjellet in the south, is a complex - the Biskayerfonna H o r s t - in which three distinct components have been identified. (i) The essential core of the horst is formed of metamorphic rocks of the Krossfjorden Group and dominated by schistose pelites in the north (Biskayerhuken Formation) and are underlain by pelites, quartzites, amphibolites and gneiss (Montblanc Formation). (ii) The Richarddalen Complex is a thrust mass of older rocks resting on and in the Biskayerfonna subgroup. It is noteworthy for its eclogites and other high grade rocks of distinctive appearance and its established Proterozoic tectonothermal history in contrast to (i) above which together with (ii) suffered Caledonian tectogenesis. This distinctive complex is not matched elsewhere in the Biskayerfonna-Holtedahlfonna terrane nor in that to the west. It is possible that, being an allochthonous thrust mass, it was transported westward from the Andr6e Land terrane basement in the east where the basement is nowhere exposed. (iii) The Siktefjellet Group of Silurian or Devonian clastics is the oldest of the Liefde Bay Supergroup and exposure is confined to the southern part of the Horst, north of Liefdefjorden. Northerly tectonised basal conglomerates and sandstones are succeeded in the south by conglomerates and sandstones of the lower formations of the Red Bay Group. The stratigraphy, structure and petrogenesis of this horst structure north of the Liefdefjorden were largely worked out by D. G. Gee (Gee 1966; Gee & Hjelle 1966; Gee & Moody-Stuart 1966) with subsequent work by Cambridge, Mtinster and Oslo Groups. Ohta, Gjelsvik & McCann (1995) noted a Horneb~ekpollen thrust zone in Liefdefjorden.

(c) South of Liefdefjorden. Whereas the Rabotdalen Fault appears as a vertical feature with indications of strike-slip the Bockfjorden Fault is a high angle thrust, which dips east with possible low angle thrust masses and klippen of the Andr6ebreen sandstone overlying the metamorphic horst. First mapped as klippen (Gee & MoodyStuart 1966) the possibility of unconformable outliers cannot be ruled out). The fault zone seen near the south of Borebreen has some irregular mylonitic patches consistent with earlier strike-slip later disturbed by dip-slip. The larger southern or Holtedahlfonna segment of the Biskayerfonn~Holtedahlfonna Horst was mapped in some detail by Gjelsvik (1979) and subsequently the Germaniahalvoya area bordering in Liefdefjorden has been worked by a German group (e.g. Piepjohn & Thiedig 1992).

(b) The Hannabreen Fault lineament (Rabotdalen-Bockfjorden Fault). This enigmatic structure runs obliquely between the two boundary faults (BBF and RFF) from north of Rivieratoppen through Hannabreen, across Liefdefjorden to join the Breibogen Fault south of Bockfjorden. It is relatively straight and a controlling feature to the north and the south but not obviously continuous at the surface in the middle tract north of Hannabreen. North of Liefdefjorden it bounds between the Biskayerfonna Horst and the Raudfjorden Basin and between the Biskayerfonna Group metasediments to the east and the Lerneroyane marbles and pelites to the south (HBF on Fig. 8.4). South of Liefdefjorden the main horst of Lerneroyane marbles rests on the lower formations of the Krossfjorden Group, and occupies the high ground to the west of the Hannabreen Fault. To the east are Red Bay Group sandstones of the Andr6ebreen Formation and the enigmatic ?late Ben Nevis Formation rocks distinguished by A. McCann (pers. comm.). The fault is a distinctive feature, probably with an earlier Caledonian strike-slip history rejuvenated differentially with dip-slip displacement in late Red Bay time. It has also been referred to where best seen as the Rabotddalen Fault in the north (Gee & Moody-Stuart 1966) and to the south a less regular trace, but still a major tectonic feature is referred to as the Bockfjorden Fault. Hannabreen unites the two but the fault cannot be seen there.

East of the Hannabreen Lineament (Bockfjorden Fault) is the strip of Andr6ebreen Formation as correlated by Gjelsvik & Ilyes (1991). It had been thought to be part of the Siktefjellet Group rather than Red Bay Group partly because of its intense deformation (Gee & Moody-Stuart 1966). Samples of structural detail in small E - W transects were depicted by Piepjohn & Thiedig (1992, fig. 4). The strata, generally striking N-S, dip steeply both E and W with complex variations including folds and breccia zones. High angle strike faults are mostly normal, others and lower angle faults are reverse. Oblique faults generally trend N E - S W and mostly, but not all, show sinistral strike-slip displacements. The picture is of remarkably complex and intense deformation with a dominant net compressive E-W component and later relaxation, although this cannot be explained without a degree of transpression. Immediately east of the Breibogen Fault the Wood Bay strata are virtually undeformed so making this a Haakonian deformation phase of Gee (1972) not pre-Red Bay (as Gee & Moody-Stuart suggested) but continuing to mid-Red Bay Group time. Coeval diastrophism is evident north of Liefdefjorden but by no means with this degree of tectonism. West of the Breibogen Fault and south of the Hannabreen Fault. The Holtedahlfonna Horst is the core of the terrane south of Liefdefjorden. Piepjohn & Thiedig (1992) recorded the metamorphic Krossfjorden Group succession thus:

marble (Lerneroyane Fro) pelite (Biskayerfonna Subgroup) (gneiss) migmatite Mapped by Gjelsvik (1979), the migmatite and pelite forms the axis of the horst and the marble the outer cover which is disposed anticlinally so as generally to crop out along the flanks. The Sverrefjellet Quaternary volcanic cone formed where the Breibogen Fault joins the Bockfjorden (Hannabreen) fault. The structure seen in the pelites in Germaniahalvoya, and depicted by Piepjohn & Thiedig, shows a complex pattern of bedding foliation with flatlying isoclinal folds and asymmetric overturned folds with low dips to the west and verging eastwards (Fig. 15.4). This is interpreted as the main Caledonian structure which preceded the sedimentation of the Liefde Bay Supergroup rocks. The lineation is N-S and boudinage noticed by the author in the marbles also suggests N-S elongation, in a dominantly compressive regime, possibly verging into a transpressive one and leading to the transcurrent movements as seen in the two bounding faults. These same deformation structures are found in the xenoliths and palaeosomes of the migmatites.

150

CHAPTER 8

The horst plunges northwards about 5~ to 10~ at Liefdefjorden so that the migmatites do not appear north of Liefdefjorden. Preston (1959), who described in some detail the southern end of the horst, noted a NNW-SSE fault between Snofjella and Dovrefjell with downthrow to the east and Red Bay strata flanking each side. Minor marginal normal faults are sympathetic with the antiform. However, along the western part of the ridge there is a system of reverse faults involving both crystalline and Red Bay rocks. The only deformation suspected to be of Paleogene age is seen in the sinistral offsets of all three fault lineaments (Breibogen, Hannabreen and Raudfjorden). One set of offsets of about 2 km each is at the latitude of Liefdefjorden, another further south from Seligerbreen, to B6rrebreen, more at Svertefjellet, and still further south at Sigurdfjellet opposite the head of Wijdefjorden. Seen on the 1:500 000 map of Hjelle & Lauritzen (1982) these displacements could all be the response north of the West Spitsbergen Orogen of its thrust to the NE. A structural study of Red Bay Group strata south of Liefdefjorden by A. McCann (pers. comm.) suggests inter alia that the strike-slip fault running SE from Hornemantoppen swings round into an east-verging thrust along the eastern outcrop of the Red Bay strata east of Monacobreen. This could also be a Paleogene effect, but he did not think so. Indeed he argued that the long straight antiformal horst, which appears truncated south of Holtedahlfonna by relatively undeformed Wood Bay Formation, was deformed in a distinctive Monacobreen Phase, marked by the inferred unconformity between the Red Bay and Andr~e Land groups. It might be added that the straightness of the antiform, parallel to the boundary faults (RFF & BBF) could be a transpressing rejuvenation of those faults.

8.5.5

The Raudfjorden Fault (RFF)

A NNW-SSE-trending fault along Raudfjorden, Monacobreen and Isachsenfonna has appeared on most geological maps since Nathorst's (Suess 1888) map. It follows the tectonic grain of the northwest complex and does not appear to cut either Wood Bay or Carboniferous strata south of Kronebreen. Some maps (e.g. Dallmeyer et al. 1990) connect it with the Pretender Fault which cuts Carboniferous and Devonian rocks (Andresen & Welbon 1991) although the latter is 5-10 km west of the projected southward trace of the straight Raudfjorden Fault. At Konglomeratodden (east of Raudfjorden) metamorphic rocks to the west are faulted against the Konglomeratodden Member to the east, which underlies the Wulffburget Member of the Rivieratoppen (conglomerate) Formation. A straight line can be drawn south separating exposures of metamorphic from Red Bay Group rocks. However, there are few localities where the actual fault contact can be observed as A. McCann (pers. comm.) has reported. With the exception of the minor sinistral offsets which are paralleled in the Breibogen Fault and are of presumed Paleogene age the straight trace implies an origin by strike-slip possibly following transpression. Once formed, such a fundamental fault would be the locus of later displacement.

8.5.6

Western Northwest Terrane

The northwest part of Svalbard, west of the Raudfjorden Fault (RFF) is a unified terrane, comprising mainly pre-Devonian metasediments and related igneous rocks with local occurrences of overlying or in-faulted Devonian deposits. The general trend of both structural fabric and lithological boundaries is N S . The overall structure may be described as an anticlinorium to the west and synclinorium to the east plunging gently to the S and so exposing deeper structural levels successively towards the centre and north.

Hjelle (1979) subdivided this complex into four areas: (i) (ii)

(iii)

(iv)

southern area predominantly of metasediments (the Krossfjorden Group); central and northern gneisses and migmatite area in which high grade metamorphics are intruded by a late tectonic batholith; western transition area (predominantly metasediments at higher grade than area (i) and bounding area (ii) in the west with transitional facies; eastern transition area, similar to (iii) but on the eastern flank.

Polyphase deformation was recognized in the metamorphic rocks to the south by Gee & Hjelle (1966) and Hjelle (1979). Of the three fold facies distinguished, the majority were identified as F2 which is associated with minor thrusting verging to the west. The thrusting was suggested to be related to the main mid-Silurian tectogenesis occurring here in lower to upper amphibolite facies; it could be later. The peak metamorphic conditions (inferred from garnet textures) appear to predate F2 in the south: the F1 event was associated with upper amphibolite facies in the late Proterozoic and early Paleozoic interval. However, evidence of an F2 fabric in the palaeosome of the migmatites indicates that migmatization postdated F2. F3 on the above scheme would be the formation of the anticlinorium and may be associated with faults downthrowing to the west in the west. Emplacement of the Hornemantoppen Batholith occurred during the last phases of ductile deformation. The intrusion was dated at 414-t-10Ma (Rb-Sr) and movement on the major westward directed thrust between Lilleh66kbreen and Smeerenburgfjorden may be related to emplacement of this granite. In the deeper rocks of the Nissenfjella Formation to the north, Ohta (1969) described the gneisses in three stages from fine grained banded gneisss, through layered gneiss to granitic migmatite. Successive fold phases showed a general foliation dip to the east with a gentle southerly component and a consistent N-S lineation. Then the granites were formed: firstly a plagioclase-porphyroblastic granite, then a grey granite and then the Hornemantoppen quartz monzonite. The last two were described as late and posttectonic. Their NW-SE trend cuts obliquely across the earlier N-S fabric. It is consistent with a local sinistral transtensional phase. There seems to be too little evidence from which to distinguish more than one mid-Paleozoic tectonic sequence. Two narrow Devonian graben trending NNW-SSE are superimposed on this in the south at Mitrahalvoya and Blomstrandhalvoya. In both areas extensive red staining at the surface suggests an exhumed Devonian unconformity, but the sediments are only preserved in the graben. Of these the Blomstrandhalvaya-Lov~noyane Basin is the best known in which the pale marbles of the Generalfjella Formation contrast with the overlying red sediments exposed both on the peninsula (now an island) and on the islands scattered in Kongsfjorden. Gjelsvik (1974) first drew attention to these rocks on the islands (which for many years have been bird sanctuaries until 15 August) (Fig. 8.8). The sediments are locally derived red conglomerates and grey green sandstones, shales and pebble conglomerates and resemble the rocks of Raudfjorden in both lithology and setting and are probably equivalent to the Red Bay Group. Russian geologists were said to have found fossils suggesting Early Devonian age. The structural setting is complex. Gjelsvik (1974) suggested a narrow graben bounded by steep faults which are observed as shear zones in two localities. The sheet, 3G of Hjelle & Lauritzen (1982) showed a western fault as a thrust from the west with marble on the hanging wall over Devonian. However, their eastern margins show marble to overthrust the sediments towards the north or northwest. Thiedig & Manby (1992) from the mapping of research students (M. Kempe and U. Nieloff) described the structure of Blomstandhalvoya which, in E-W section through N-S striking faults and folds, shows westwards verging folds and thrusts. This is consistent with either Haakonian or Svalbardian deformation and not

NORTHWESTERN SPITSBERGEN with Paleogene deformation which would be expected to strike N W - S E and verge to the NE. Sediments were all generated by active faulting which would suggest Haakonian transpression as in the Biskayerfonna-Holtedahlfonna terrane.

Mitrahalvoya. An analogous but smaller N S structure (15-18 km W of the above) is evident in Mitrahalvoya, the faults and red staining obtain but no sediments have been recorded.

The Kollerbreen zone. A Kollerbreen Formation has been introduced in the notes to Fig. 8.6. Ravich (1979) not only regarded it as a Caledonian migmatite complex but he drew attention to a narrow zone 2-4 km wide, extending 40 km N-S from Kollerbreen (at the head of the NE branch of Krossfjorden to Kronebreen at the head of Kongsfjorden. Its contacts with other units were described as mainly tectonic. It is indeed a fracture zone and this may have led Abakumov to treat this sheared migmatite as early Proterozoic. Ravich described its petrology in detail. This fracture zone would appear to be another ?Early Devonian strike-slip shear zone. Abakumov & Chaika (1996) described this 'Smeerenburgfjorden Group' as including the highest grade rocks in the area with amphibolite facies metamorphism and relicts of granulite facies.

151

(3) Late Neoproterozoie. The Richarddalen Complex also shows evidence for a thermal event around 620 Ma.

(4) Mid-Silurian: main Caledonian-Smeerenburgian.

The time of deformation and Smeerenburgian magmatism of the Krossfjorden Group strata (and adjacent Richarddalen Complex) is constrained by metamorphic ages, by the age of the late and post-tectonic granites, and by the unconformable cover of both Siktefjellet and Red Bay Group conglomerates which, while deformed, have neither suffered such intense tectogenesis nor recorded any tectonothermal activity.

(5) Late Silurian-Early Devonian: Haakonian. The main structures affecting the Siktefjellet through Lower Red Bay Group formations are constrained within the Biskayerfonna-Holtedahlfonna terrane probably before or during Fr~enkelryggen Formation time. It is thought likely that the sedimentation and structures seen north of Kongsfjorden were also formed in a coeval episode. A late Devonian age is also possible. However, relatively undeformed Wood Bay strata occur to the southeast which makes it less likely that these structures resulted from Svalbardian movements. (6) Early Devonian (post-Red Bay, pre-Andr& Land groups).

8.5.7

The Pretender Lineament

Possibly appropriately named, this lineament has been postulated as extending south from the Pretender Fault east of Ny-Alesund through outer Isfjorden and south beneath the fold belt of the West Spitsbergen Orogen or beneath the Paleogene formations of the Central Basin. It was suggested (Welbon & Andresen 1992) that it may have had a Devonian history by analogy with parallel faults to the east described in the foregoing sections, moreover, that it marked the boundary between the Nordfjorden Block and the St Jonsfjorden Trough. It had been suggested (Mork et al. 1982) that the lineament was active in Triassic time and was the locus of thickening of Triassic strata westwards. However, in Chapters 10 and 18 it is argued that the observed thickening does not require a fault. For these pre-Cenozoic functions other faults might serve as well or even better, such as the Kongsfjorden-Hansbreen Fault postulated as a terrane boundary (Harland & Wright 1979; Harland, Hambrey & Waddams 1993). The visible evidence as described by Welbon & Andresen is of a fault, or fault zone, in the Pretender Mountains with E - W extension, and normal faulting down to the west, and approximately 400 m offset (?apparent dextral). Paleogene deformation structures are cut by these faults which are thus post-Eocene or later. The older displaced rocks appear to show no evidence of syn- or presedimentary faulting so that the earlier history is surmise. However, the opinions expressed in their abstract (Welbon & Andresen 1992) may well be justified when more evidence is published.

8.5.8

Timing of deformations

A summary of conclusions with a discussion of the Paleogene component of deformation follows. (1) Arehean. Zircons in the Richarddalen complex indicate a possible event around 3234 4-43 Ma but it is not related to any recorded structure.

(2) Early Neoproterozoie: 'Grenvillian'. The Richarddalen Complex records clear isotopic evidence of a tectonothermal event around 965 Ma.

Folding of Biskayerfonna-Holtedahlfonna anticline. This was referred to by McCann (pers. comm.) as the Monacobreen Phase. (7) Late Devonian: Svalbardian. The main structures affecting the Andr& Land Group strata are clearly Late Devonian in the south where constrained by an unconformable cover of ?late F a m e n n i a n Tournaisian strata. There is no obvious constraint in the north where there is no Carboniferous outcrop. There was certainly a compressive component. Evidence is also consistent with transpression which has not been disproved. The tectonic sequence could be: transcurrence-~ transpression-+ compression.

(8) Carboniferous: 'Petunian' from Petuniabukta.

To the south of the sector movements in line with the above mentioned faults continued at least through Moscovian time, and appear to have been extensional as in the Billefjorden Trough. An extensional regime would have been consistent with the intrusion of the monchiquite dykes at Krosspynten dated at 3 1 5 + 5 M a (Gayer et al. 1966 recalculated c. Bashkirian) also along the Billefjorden Fault Zone. (9) Paleogene: Spitsbergian. The West Spitsbergen orogeny is known to have deformed strata, conspicuously late Paleogene, but also Mesozoic, as far east as the Lomfjorden Fault Zone. Thrust structures along rejuvenated older fault zones are well established. It would therefore be surprising if such effects did not extend at least a little north of the main Carboniferous outcrops so that the minor deformation of the Krosspynten dykes is consistent with this effect (Manby & Lyberis 1992). On the other hand the main orogeny in the west is conspicuous only a little north of Kongsfjorden (Welbon & Andresen 1992). For example the Lomfjorden Fault Zone which cuts Carboniferous strata well north of the deformation reported by Andresen et al. (1992) appears not to be affected. Therefore there is no reason to attribute any of the main deformation of Devonian or earlier strata to the effects of the West Spitsbergen Orogeny. Moreover, the vergence of the Andr& Land and Dickson Land Devonian structures is westward which is the opposite of all the Paleogene effects. Cleavage in the folded structure in north Andr& Land is argued by Manby & Lyberis (1992) to have required more overburden than would have been supplied by Devonian strata. It is not known what Devonian strata were removed, and in any case the fold structure, claimed by those authors to imply a stratal shortening of

152

CHAPTER 8

not less than 45% might well have built up the necessary overburden. In any case the basal Paleocene unconformity cuts down through cover strata back to Permian at Kongsfjorden and further north erosion had probably removed most post-Devonian cover by Eocene time. Similarly the westward verging structures north of Kongsfjorden do not fit a Paleogene eastward verging model. The most likely Paleogene deformation in the Northwest sector is the sinistral displacement of the two otherwise straight faults (Raudfjorden and Breibogen) and also the related oblique faults, notably one trending ESE, sinistrally displacing the northern part of the Hornemanntoppen Batholith, passing through the head of Liefdefjorden where it displaces the RFZ and possibly bounding the Red Bay Group on the east of Monacobreen as the thrust structure noted by McCann (pers. comm.). While not constrained in age it is eastward verging and so is sympathetic to the kinematics of the West Spitsbergen Orogen. A distinctive deformation belt extends up to 4kin on either side of the Billefjorden fault forming a wide zone with presumed Paleogene displacements as outlined by Harland et al. (1974) and upgraded by McCann & Dallmann (1996).

8.6

Offshore geology

The offshore area to the north of Spitsbergen consists of a shallow, flat region with water depths less than 200m. To the west and northeast, this bank drops off sharply onto the abyssal plain of the Eurasian Basin, with water depths in excess of 1500m. To the northwest the bank drops only slightly to a plateau, with depths about 800 m. The plateau extends to the north and curves round in a hook-shape to the northeast, where it slopes off onto the abyssal plain. This hook-shaped seafloor promontory is the Yermak Plateau (Fig. 8.12). The shallow inshore areas contain several smaller banks and basins. In particular, these are Sjubrebanken, to the west of Albert I Land; Danskoya Basin, to the northwest of Albert I Land; and Norskebanken, to the north of Haakon VII Land and Andr6e Land.

8.6.1

The geology of the plateau has been subject to geophysical surveys (e.g. Feden, Vogt & Fleming 1979; Jackson et al. 1984; Eiken 1993) and by the Ocean Drilling Program (Myrhe, Thiede & Firth 1994). It has generally been proposed that the northern part of the plateau comprises some form of oceanic crust, wheras the southern portion is of continental character similar to Svalbard (Feden, Vogt & Fleming 1979). It has been interpreted by Feden et al. and Jackson et al. as once having lain adjacent to the Morris Jessup Rise, situated off northern Greenland. Together, they may have formed an Iceland-like massif of oceanic crust, with the greatest rate of plateau development occurring between anomaly 18 and anomaly 13 time. The massif split after anomaly 13 time when the North American and Eurasian plates drifted apart. Jackson et al. recorded four seismic profiles. Off the northern flank of the plateau (line 1) lies oceanic crust of the Eurasian basin, with up to 2 km of sediment cover. The oceanic crust within the basin is thin, only 2-3 km. On the plateau itself, line 3 reveals 8 km of crust similar to layer 2 oceanic crust, underlain by a minimum of 10km of crust similar to layer 3 oceanic crust. On line 4 the southern end reveals continental crust similar to that throughout Spitsbergen. Gravity data indicates that the crust off the plateau is only approximately 20 km thick, which for the continental crust represents significant thinning, perhaps by as much as 20%. Seismic data for the southern part of the plateau was provided by Eiken (1993). Over 1 km of well-stratified sediments are present in the area, except for in the vicinity of the Sverdrup Bank which has no basement cover. Three sequences were recognized in the cover strata: YP-1, YP-2 and YP-3. Sequence YP-1 is only observed in the SW-most part of the plateau. It consists of subparallel reflectors, and infills basement topography. Assuming that topography was rift-related, then the sequence is probably of Neogene age. Sequences YP-2 and YP-3 show evidence of working by bottom currents, probably from the West Spitsbergen Current as it flows northwards into the Arctic Ocean. The seismic sections show smooth reflectors from the top of fault blocks, many of which are tilted. Eiken (1993) believed that Tertiary strata were probably present beneath the Sverdrup Bank. Basement rocks were not observed beneath the thick sedimentary cover at Sophie Canyon. West of the Hornsund lineament YP-2 downlaps to the west, and forms an elongate NNW-SSE trending depocentre. The most southwesterly part of the plateau was interpreted by Eiken as being underlain by Tertiary volcanic crust, wheras the southeasternmost plateau is formed by older continental crust, as the seismic velocities and reflection characteristics are more varied. The Ocean Drilling Program investigated the plateau at Sites 910, 911 and 912 (Myhre, Thiede & Firth 1994). Each hole reached approximately 500 m below sea floor (mbsf) predominantly through homogeneous very dark grey silty clays and clayey silts, of Quaternary and Pliocene age. Two subunits were identified at each site on the basis of an uphole increase in dropstone abundance and size. The increase occurred at a depth of 208 mbsf at site 910, 380 mbsf at site 911 and 40 mbsf at site 912. Dropstones were most abundant at site 912 on the shallow SW edge of the plateau. They are mostly of siltstone, sandstone and mudstone composition, but igneous and metamorphic clasts were also present.

8.6.2

Fig. 8.12. Principal bathymetric features off northwest Spitsbergen (simplified from Eiken 1993).

The Yermak Plateau

Sjubrebanken

Sjubrebanken is a submarine bank in less than 200m of water, situated west of Albert I Land and north of Prins Karls Forland. Eiken (1993) presented seismic sections across the area, and identified a possible northward continuation of the Hornsund lineament. To the west of the lineament is a broadly westwarddipping sediment prism, with an approximate width of 140 km in the north and 110 km in the south, overlying volcanic basement. To the east of the lineament lies continental basement with graben structures; there is very little sediment cover in the southern part of the bank, but more in the north.

NORTHWESTERN SPITSBERGEN The seismic profiles reveal three sequences, YP-1, YP-2 and YP-3, all correlated with those on the Yermak Plateau (see above). The upper sequence (YP-3) has a depocentre on the outer shelf, from where it thins and downlaps to the west. YP-2 and YP-3 together are approximately 2 k m thick at their joint depocentre, where they form a 10km wide anticline showing a seismic crestal bright spot suggesting the presence of gas. The two sequences are probably of late Miocene to Plio-Pleistocene age.

8.6.3

Danskoya Basin

North of Sjubrebanken lies the Danskoya Basin. It is a 4-5 km thick trough-like sedimentary basin, oriented N-S and approximately 100 km by 20 km. Four sequences have been identified on seismic sections (Eiken 1993), designated DB-1 to DB-4. The major sequences are DB-1, 2 & 4 all of which onlap southwards. DB-3 contains thin progradational lenses. Most reflectors are truncated:

153

DB-1 by DB-2 to the south; DB-2 and DB-4 by the seafloor. Eiken explains this pattern by syn- and post-depositional uplift of N W Svalbard combined with subsidence of the basin.

8.6.4

Norskebanken

Situated due north of Spitsbergen, Norskebanken is the site of a basin with a 2-4 km thick sedimentary infill. The southern margin of the basin is marked by a north-throwing extensional fault (the Moffen fault), to the south of which lies Paleozoic rocks which continue onto onshore Spitsbergen. Eiken (1993) divided the sequence into a lower megasequences NB-1 and an upper sequence NB-2. NB-1 contains internal unconformities, interpreted by Eiken as the result of Cretaceous and Tertiary pre- and syn-rift movements. The megasequence is truncated at the outer shelf by NB-2, which is thought to consist of Miocene and younger strata. NB-2 was deposited rapidly with a depocentre at the outer shelf, and was related by Eiken to the uplift and glacial erosion of Svalbard.

Chapter 9 Central western Spitsbergen W. B R I A N

9.1 9.1.1 9.1.2 9.2 9.2.1 9.2.2 9.3

9.3.1 9.3.2 9.3.3 9.3.4 9.4 9.4.1 9.4.2 9.5 9.5.1 9.5.2 9.5.3 9.6 9.6.1

HARLAND

with contributions with ISOBEL

Paleogene rocks, 154 Kings Bay Coalfield (Ny-?desund), 154 Forlandsundet Graben, 157 Mesozoic strata of Oscar II Land, 158 Kapp Toscana Group, 158 Sassendalen Group, 159 Late Paleozoic strata of Oscar II Land (Biinsow Land Supergroup) (W.B.H., I.G. & R.A.D.), 159 Tempelfjorden Group, 159 Dickson Land Subgroup (Gipsdalen Group), 159 Charlesbreen Subgroup (Gipsdalen Group), 160 Billefjorden Group, 161 Early Paleozoic rocks, 162 Bullbreen Group, 162 Vestg6tabreen Complex, 164 Proterozoic strata of Oscar 1I Land, 165 Comfortlessbreen Group, 165 St Jonsfjorden Group, 165 Kongsvegen Group, 166 Pre-Carboniferous rocks of Prins Karls Forland, 166 Grampian Group (Early Paleozoic), 167

The West Spitsbergen Orogen extends along the western side of Spitsbergen from Kongsfjorden to Sorkapp. It is the product of the latest main deformation event in Svalbard (Spitsbergian) dated provisionally as Eocene. The deformation is of a compressive or transpressive nature associated with the dextral strike-slip displacement between Svalbard and Greenland through Cenozoic time. Within this fold and thrust belt earlier diastrophism is evident: Minor Late Cretaceous tilting with uplift took place. The main events were mid-Paleozoic. The mid-Paleozoic tectogenesis is commonly referred to as Caledonian. However the age of deformation appears to be mid-Ordovician rather than the typical mid-Silurian of the central and eastern terranes of Svalbard. To avoid confusion this is referred to as the Eidembreen teetogenesis (analogous with the M'Clintock Orogeny of northern Ellesmere Island). Some uncertainty must remain as to whether there was any Silurian diastrophism or more likely, late Devonian-Early Carboniferous tectonism to match the Ellesmerian events of Arctic Canada. The rocks divide naturally into younger (Carboniferous through Eocene) strata, i.e. post-Devonian, and pre-Devonian older rocks, there being no Devonian exposure within the orogen. Whereas the West Spitsbergen Orogeny was Paleogene (treated in Chapter 20) the orogen comprises the whole body of rock whether formed earlier or later. Because of the complex earlier history and variety of strata and structure along its length it is convenient to treat the structure in two parts, north and south of Isfjorden (Chapters 9 and 10 respectively). In this chapter the area treated comprises Oscar II Land and Prins Karls Forland (Figs 9.1 & 9.2). The eastern boundary remains indefinite and will overlap in treatment with chapter 4 because the younger rocks of the Central Basin extend westwards and the structure related to the orogenic compression extends far eastwards. The Carboniferous and Permian (Btinsow Land Supergroup) strata south of Isjforden in Nordenski61d Land are for convenience treated in this Chapter rather than in Chapter 10. Flood (1966) reported on mineralization especially in St Jonsfjorden where in 1919 and 1920 N.E. Co. prospectors set up Copper Camp on the south side of the fjord on the basis of chalcopyrite claims. Mineralization there has, however, not been exploited.

GEDDES

& PAUL

A. D O U B L E D A Y

9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.7 9.7.1 9.7.2 9.7.3 9.7.4 9.8 9.8.1 9.8.2 9.8.3 9.8.4 9.8.5 9.9 9.9.1 9.9.2 9.9.3 9.10

Scotia Group (Late Vendian-Ediacara), 167 Peachflya Group, 167 Geikie Group, 167 Ferrier Group, 167 Pinkie Formation, 168 Structure of Oscar II Land (W.B.H. & P.A.D.), 168 Northwest Oscar II Land, 168 Southwest Oscar II Land, 168 Central and eastern Oscar II Land, 170 The St Jonsfjorden area, 171 Structure of Prins Karls Forland, 171 Sequence and age of deformation, 172 Vergence of deformation, 172 Faulting, 172 Metamorphic environments, 174 Conjectural synthesis, 175 Structure of the Forlandsundet Basin (W.B.H. & P.A.D.), 175 Structure of the infill, 175 Palaeostress history of Forlandsundet Basin (phases 1-3), 175 Origin of the Forlandsundet Basin: current models, 176 A tectonic interpretation of the West Spitsbergen Orogen; northern segment, 177

9.1

Paleogene rocks

9.1.!

Kings Bay Coalfield (Ny-~,lesund)

The previous published authority on this coalfield was by Orvin (1934). He described this Tertiary coal field in detail from surface and subsurface data. The rocks were given the name Ny-Alesnnd Formation by Challinor (1967); Orvin's two divisions were then described as members as follows.

(2) Green Sandstone Member (c. 100m). Quartz grains with a diameter of up to 0.5 mm constitute about one third of the rock. In addition grains of quartzite, shales, feldspar and marble occur, and are weathered brown from oxidation of pyrite. Sandy shales are rich in plant fossils- mainly tree leaves. No marine fossils have been recorded. About 35m from the base is the Ragnhild (coal) Seam and at the base is the Josefine Seam.

(1) Grey Sandstone Member (c. 95m). The upper 70m of this member is a pale sandstone, the top 20m of which contain conglomerates. Below this the Agnes Otelie Seam. The remainder of the formation comprises the 'Lower Coal Horizon', which is variable in sequence and thickness with the Advocat Seam at the top; 10 to 30 m below is the Sofie Seam and at the bottom (8-12 m below) is the Ester Seam which rests directly on the bottom shale. Owing to separation from other such strata in the Central Basin to the south, no precise correlation can be attempted. However, there are similarities with the Firkanten Formation (Paleocene) and the overlying Basilika formation of the Central Basin. Palynological and other evidence is consistent with this correlation. The formation overlies the Bottom Shale Formation (in the east of the coalfield) and oversteps it to the west onto the Kapp Starostin Formation. The history of mining and the sequel at Ny-,~lesund has been recorded by H a n o a (1993) with many personal and community details.

CENTRAL WESTERN SPITSBERGEN

155

Fig. 9.1. Topographic and place name map of Oscar II Land and Prins Karls Forland, based on Topographical Map o f Svalbard 1 ."500 000, sheets 1 and 3, Norsk Polarinstitutt.

The current classification of rock units a p p r o v e d by the SKS ( D a l l m a n n et al. 1995) (Fig. 9.3) combines elements o f Orvin (1934), C h a l l i n o r (1967) a n d Livshits (1974) as follows:

Van MijenfjordenGp Ny-Alesund Subgp (Challinor 1967; SKS 1995) BroggerbreenFm (Orvin 1934; SKS 1995) Bayelva Mbr (SKS 1995) Leirhaugen Mbr (SKS 1995) Kongsfjorden Fm (Orvin 1934; Livshits 1973; SKS 1995) TvillingvatnetMbr with M~rebekken conglomerate (SKS 1995) Kolhaugen Mbr (SKS 1995)

The Van Mijenfjorden Group was defined as combining the six Tertiary formations of the Central Basin, the lower two of which appear to correlate with the two of the Ny-Alesund Subgroup in spite of separation by the West Spitsbergen Orogen in Broggerhalvoya. The Ny-~i,lesund Subgroup is Challinor's (1967) Formation raised in rank so that his two members are raised to formation rank. The name Kongsfjorden Formation follows Livshits (1974) and the overlying Broggerbreen Formation was named by Livshits the Ny Alesund Formation but as that was already in use the new name was proposed by SKS (1995). Each pair of members proposed by SKS (1995) was based on unpublished work by Midboe, the only published detail on the coalfield

156

CHAPTER 9

Fig. 9.2. Diagrammatic outcrop map of central west Spitsbergen, based on various data from Harland, Hambrey & Waddams (1993), and SKS (Dallmann et al. 1996, fig. 3c),

CENTRAL WESTERN SPITSBERGEN

157

Fig. 9.3. Geological map and stratigraphic section of the Ny-~Jesund coalfields, redrawn from Orvin (1934) and from Midboe in SKS (Dallmann 1995, figs lb and 2b), with permission. since Orvin. The relevant detail appears in the SKS publication from which the following is taken. Broggerbreen Fm (Orvin 1934; SKS 1995) This is the Green Sandstone of Orvin (1934) and Green Sandstone Member of Challinor (1967) and has been recommended for division into two members by the Committee. It comprises conglomerates, sandstones, shales, coaly shales and coals. Bayelva Mbr, > 160 m the upper surface is truncated by a thrust surface: it consists of alternating conglomerates, sandstones, shales, coaly shales and coal seams of which the Josefine Seam is at the base of the Member with Ragnhild, KBI and KB seams higher up. Leirhaugen Mbr, 5-20 m consists of alternating conglomerates, sandstones, shales, coaly shales and the Agnes-Otelie coal seam at the base. It is distinguished because interpreted as transitional between the overlying continental unit and the underlying marine unit. Kongsfjorden Fm (Orvin 1934; Livshits 1974)= Grey Sandstone of Orvin (1934) and Grey Sandstone Member of Challinor (1967). Similary three members have been proposed. Tvillingvatnet Mbr, 15-70 m (SKS 1995 from Midboe unpublished). It is of coarse and medium grained marine bioturbated sandstone, pebbly sandstones and conglomerates resting with erosional unconformity on the Kolhaugen Mbr in the SE and on the Morebekken Mbr in the NW. Borehole log 38/76 shows only the upper part as conglomeratic and the lower part, sandy, pebbly and contorted. Morebekken Mbr, 10-20m (SKS 1995 from Midboe) consists of mainly coarse conglomerates with thin beds of coarse sandstone. The pebbles are of chert and glauconitic sandstone as from the underlying (Permian) Kapp Starostin Formation. Kolhaugen Mbr, 0-40m (SKS 1995 from Midboe) consists of rapidly alternating fine-grained sandstones, shales, coaly shales and coal with welldeveloped coal seams from the top: Advocaten seam, Sofie seam and Ester seam at the base of the member where the coaly beds rest directly on the (Early Triassic) Vardebukta Formation (Lower shale of Orvin 1934). It thins, as does the Vardebukta Formations to the west of the coalfield. 9.1.2

Forlandsundet Graben

The sedimentary strata appear in a scattered a r r a n g e m e n t dependent on the complex tectonic sequence of the G r a b e n which is

discussed in Chapter 20. The m o s t recent stratigraphic w o r k by RyeLarsen has only been partially published by SKS ( D a l l m a n n et al. 1995), which the notes below follow (Fig. 9.4). Despite the fragmentary nature of the stratigraphic evidence, a composite succession has been established that indicates an apparent thickness of as m u c h as 5 km. A l o n g the eastern and southwestern margins of the basin, alluvial-fan deposits are well d o c u m e n t e d . They are characterised by poorly sorted, unstratified conglomerate beds of debris-flow origin, and are associated with fine-grained, flat- and cross-stratified conglomerates originating as streamflow deposits (Steel et al. 1985). In the southwestern part of the area, the fan deposits apparently grade laterally (basinwards) into possible fandelta and nearshore deposits comprising a sequence of black shales, siltstones and cross-stratified or ripple-laminated sandstones. The northwestern region, with a succession 3 k m or m o r e thick, is

Atkinson1963

Livshits19671

SKS(Dallmannet al. 1995) basl~de?LaWsOrk by

Adoptedin thiswork (a possiblealternative) I KAFFI~YRACOMPLEX

McVitie (McVitiepynten) Fm

Selv~gen (conglomerate) Fm

AberdeenflyaFm MarchaislagunaFm KrokodillenFm ReinhardpyntenFm Sessh~gdaFm

r--

Ii

~ Balanus- SarstangenMbr ~

SarsbuktaMbr

I:Iil I I I

c.~ I ~ [ Kr~176 Fm ! ;~ ~o~-~1ReinhardpyntenFm !

Selv&genFm I! I I ~ ~ r J [ pyntenFm SarsbuktaMbr L /

AberdeenflyaFm

Fig. 9.4. Summary of the Paleogene stratigraphic units in Forlandsundet, modified from Rye-Larsen in SKS (Dallmann 1995, fig. 2c).

158

CHAPTER 9

characterised by black shales; associated turbidite a n d c o n g l o m e r a t e beds interpreted as a submarine-fan association. T h e marginal alluvial-fan sequences (e.g. Selvgtgen, Sarsbukta and Sarstangen formations) are laterally equivalent to the n e a r s h o r e and shallowm a r i n e deposits (Sesshogda, R e i n h a r d p y n t e n , K r o k o d i l l e n and M a r c h a i s l a g u n a formations) and to the s u b m a r i n e - f a n succession (Aberdeenflya F o r m a t i o n ) . The B u c h a n a n i s e n G r o u p was investigated by M a n u m (1962) and Livshits (1965, 1974) and E o c e n e to early Oligocene ages were obtained. M o r e recently, palynological dating on samples from the eastern m a r g i n o f the basin at Sarsbukta by M a n u m & T h r o n d s e n (1986), based on dinoflagellate studies, suggest a Late Eocene age, a l t h o u g h precise age constraints are n o t available (Kleinspehn & Teyssier 1992). C u r r e n t data therefore place the age of the F o r l a n d sundet G r o u p as Late Eocene to Late Oligocene (Feyling-Hanssen & Ulleberg 1984; Steel e t al. 1985).

Buchananisen Group (SKS 1995). This name replaces Forlandsundet Group (Harland 1969) which name is now restricted to the structural graben (Harland 1969). From seismic traverses at sea it is probably about 5 km thick. Balanuspynten Fm (SKS 1995)=Sars Fm (Atkinson 1963). Atkinson's name for the rocks on the east of the sound had priority before the rules for acceptance of names was laid down by the Committee. It conveniently combines the two members. Sarstangen Mbr (SKS 1995 from Rye-Larsen), 1050m in drill holes to metamorphic basement. It comprises fine to coarse-grained sandstones or conglomerates and siltstones. SarsbuktaMbr (SKS 1995 from Rye-Larsen unpublished) 600+ m with faulted contact to east and lower boundary not exposed consists of pebbly to boulder sized multicolored conglomerates with medium to coarse sandstones and rare thin siltstones. Coal and plant fragments are abundant. Feyling-Hanssen & Ulleberg (1984) suggested a mid- to late Oligocene foraminiferal age. Aberdeenflya Fm (SKS 1955 from Rye-Larsen) 2800+ m. Crops out on the northwest of the sound (northeast of the Prins Karls Forland) of alternating polymict, pebble-sized conglomerate and fine to medium-grained sandstones interbedded with siltstones and claystones. Horizontal burrows are common. Its stratigraphic relationships are not exposed. MeVitiepynten Subgp (Atkinson 1963). The following four units were named and described by Livshits (1967 and 1974) as formations and said to be equivalent to Atkinson's McVitiepynten Formation. It crops out on the west of the sound. Marchaislaguna Fm (Marchais Fm of Livshits 1967) 55 to 600+m of alternating polymict, stratified, grey to yellowish, pebble-sized conglomerates and medium-grained sandstones with siltstones and claystones with S k o lithos, Arenicolites and Diplocraterion burrows. There is a sharp, possibly erosive, boundary with the underlying member. Krokodillen Fm, 400+ m of dark silty claystones interbedded with 2 40 m thick light fine grained sandstones rests directly on Selvgtgen Fm to W and contact with the Reinhardpynten Mbr is not exposed. Reinhardpynten Fro, 210+ m of dark clay-stones, with carbonate concretions and quartzite lonestones, coarsening down to very fine sandstones and siltstones with pyrite and siderite concretions. Sesshagda Fm, >120 m of light grey medium to coarse-grained conglomeratic sandstones alternating with siltstones and clay stones in the lower part with sideritic concretions and pyrite in the upper part. The lower boundary is gradational. Selvfigen Fm (Atkinson 1963; Livshits 1972, 1974) 40 170m of pebbly to boulder-size greenish grey to yellow and red conglomerates and breccias near the graben faults from which they thin to the east. Rests with angular unconformity on the Vendian Scotia Group of Prins Karls Forland. Katfiayra Complex. The scattered exposures through much of the eastern flatland of Sarsoyra and the hills to the east, as well as the similar coastal flat of Kaffioyra to the south, have long been a puzzle because of their incoherent and disjointed arrangement. From successive short visits up to 1992 by the Cambridge group a (dextral) strike-slip melange was inferred. However Ohta, Krasil'shchikov e t aL (1995) not only detailed such a strikeslip shear zone but from petrogenetic and geochemical studies identified low-temperature, high-pressure metamorphic rocks. These green-brown dolostones and serpentinites match those of the Vestg6tabreen (?subduction) Complex at Motalafjella to the south. The Motalafjella rocks are described below (Section 4.2) where an Ordovician metamorphic age is generally accepted. The Kaffioyra Complex appears to have been part of the Vestg6tabreen Complex, but involved in Paleogene dextral shear and so forms a shear zone north of Motalafjella and Ankerfjella. The Complex is

thus (Spitsbergian) Paleogene, the original metamorphism was Ordovician, but the protoliths were probably basic volcanics in the Lovliebreen Formation of the St Jonsfjorden Group argued here (as by Harland, Hambrey & Waddams 1993) to be Early Varanger in age. Ohta et al. were of the same opinion except that they stated a middle Proterozoic age for the same rocks. A distinct facies is the green-brown dolostone, which is a magnesite rock with fuchsite, accessory chromite and chromium spinel. They are, as at Motalafjella, associated with tectonic blocks of serpentinite. Geochemical analyses confirm these affinities. Larger units have been juxtaposed in a zone to the east of the Kaffioyra Complex. From the investigations of Ohta et al. (1995), they also correlate with the Ordovician rocks south of St Jonsfjorden. In particular, the Aavatsmarkbreen Formation, taken to lie at the top of the Vendian sequence in the Comfortlessbreen Group, should belong to the Bullbreen Group. The Sarsoyra Formation is exposed as a series of white carbonate hills to the northeast of Sarsoyra. In a conglomerate clast W. T. Horsfield found a rugose coral and Scrutton, Horsfield & Harland (1976) took this to correlate with the Bulltinden Formation of ?Silurian age. Because the poorly preserved coral could equally have been Carboniferous, the age of the Sarsoyra Formation was in doubt and possibly late Paleozoic. However, the Makarjev's work reported by Ohta et al. (1995) confirms the original opinion of Scrutton et al. (1976). The Aavatsmarkbreen and Sarsoyra formations are coherent bodies within the Paleogene transpression complex so in themselves cannot be regarded as Paleogene; but they are integral parts of the graben structure. The Pinkie Formation or Complex, referred to in Section 9.6.6, has been taken as possibly the oldest part of the Prins Karls Forland sequence. It is an allochthonous thrust unit and was thought to have derived from a similar basic volcanic protolith of Early Varanger age (Harland et al. 1993). Ohta et al. (1995) also relate this to the same material, but whether it is related to a Paleogene shear zone is another matter.

9.2

Mesozoic strata of Oscar II Land

Cretaceous and Jurassic outcrops are limited to two areas on the northwest coast o f Isfjorden where they complete the n o r t h e r n frame of the Central Basin underlying the Paleogene elliptical brachysyncline. T h e y are a m a j o r consideration in C h a p t e r 4 and are omitted here. Triassic strata extend from n o r t h to south of Oscar II L a n d and are intimately involved in the fold and thrust belt o f the West Spitsbergen Orogen. The i n c o m p e t e n t Triassic shales o f the Sassendalen G r o u p dramatise the fold and thrust structures with the contrasting c o m p e t e n t K a p p Starostin F o r m a t i o n . Before the Paleogene o r o g e n y the upper Triassic units h a d already been progressively e r o d e d towards the n o r t h so that within a distance o f 100km from Selmaneset in the south to NyAlesund in the north the whole remaining Mesozoic succession was reduced to zero thickness beneath the overstepping Paleocene strata. With the loss of Cretaceous and Jurassic strata just n o r t h of Isfjorden the Triassic succession was reduced to 725m at Iskletten (without the K a p p Starostin G r o u p and the u p p e r m o s t Botneheia F o r m a t i o n ) . Southeast o f N y - A l e s u n d the V a r d e b u k t a F o r m a t i o n (Bottom Shale of Orvin 1934) is only 50 m and to the n o r t h w e s t of the coalfield Paleogene strata rest directly on P e r m i a n rocks. This section of the chapter in effect treats mainly the Sassendalen G r o u p defined by the three formations: Botneheia, Sticky K e e p and V a r d e b u k t a .

9.2.1

Kapp Toscana Group

Occurs only in southern Oscar II L a n d with a m a x i m u m thickness of a b o u t 200 m. The D e G e e r d a l e n F o r m a t i o n is of typical greenish-grey sandstones and siltstones a n d with no Tschermakfjellet F o r m a t i o n facies between it a n d the underlying Botneheia Formation.

CENTRAL WESTERN SPITSBERGEN

9.2.2

Sassendalen Group

T h e g r o u p as a whole thickens westwards a n d s o u t h w a r d s in Oscar II L a n d t o w a r d s a m a x i m u m exposed thickness between Isfjorden and Bellsund (Buchan et al. 1965). The thickening is related to a s o m e w h a t coarser grain size which led M o r k et al. (1982) to p r o p o s e a distinct n o m e n c l a t u r e for the western succession. This was partly based on the a s s u m p t i o n of a sharp increase in thickness to the west o f a postulated N - S fault. H o w e v e r , the intermediate Oscar II L a n d thicknesses of the g r o u p also fit a gradual increase in thicknesses which f r o m Sveaneset to Festningen is a b o u t from 400 to 820 m over a distance of a b o u t 55 k m as seen in the fence d i a g r a m o f B u c h a n et al. whose same three constituent f o r m a t i o n s can be recognized t h r o u g h o u t Spitsbergen as confirmed by Worsley & M o r k (1978). The Botneheia Fm, 262m in southern Oscar II Land, occurs only in southern Oscar II Land. It is characterized by laminated dark shales, often bituminous. The silty to sandy facies may be characterized by phosphatised burrow infills. The coarser facies tend to increase upwards with ripple cross lamination and with both calcareous and phosphatic cement. At Sveaneset it yields Gymnotoceras, Posidonia and Daonella f r a m i which may be more characteristic of the lower horizon. Mork, Knarud & Worsley (1982 et seq) and some later publications refer to this formation by the name Bravaisberget for the somewhat coarser and thicker facies southwest of Isfjorden. The Sticky KeepFm, 230 m at Iskletten, is a coarser unit than the Botneheia Formation. The unit also tends to coarsen upwards. In Oscar II Land this has led to a division into two members of the original Sticky Keep Fm. Kaosfjellet Mbr is a distinctive cliff-forming unit of yellow to brown weathering, laminated, shaly siltstones alternating with harder more calcareous siltstones. This competence contrast may promote small scale chevron folding, hence the name of the unit. Isldetten Mbr is a more shaly unit and typically with grey septarian limestone concretions. The Sticky Keep Fm has been referred to in the west, south of Isfjorden as the Tvillingodden Fm (Mork et al. 1982). The Vardebukta Fm, 253 m. This unit was defined in the Festningen section south of Isfjorden. At Selmaneset it is 258 m. The formation is typical of sandstones to siltstones with interbedded shales. As with the two higher formations the coarser facies predominate in the upper part which has led to the division of the formation into two members (Buchan et al. 1965). Siksaken Mbr, c. 100 m comprises alternating grey calcareous siltstones and silty limestones passing to calcarenite, light grey and white sandstones, hard siltstones and calcareous shales. Selmaneset Mbr, c. 150 m comprises somewhat softer dark grey, often calcareous, silty shales with thin hard calcareous siltstones interbeds, sandier towards the top with clay-ironstone concretions. Fossils are few. The lower boundary with the Permian Kapp Starostin Fm is conspicuous. The Bottom Shale of Orvin (1934) in the Ny-~,lesund coalfield= Vardebukta Fro, 0-50m of Challinor (1967). This formation is thickest in the east of the coalfield, where it underlies the Kongsfjorden Formation. It is overstepped in the west. Exposure is limited to a few gully sections, and the main information derives from drill cores. No fossils have been recorded. The upper part is distinguished by variable green, brown and red shales and claystones with conglomerate. Orvin (1934) suggested that it had been derived by erosion of rocks equivalent to the lower part. The lower part is of more uniform shale and is characterised by basal breccias and limestone. The breccias are clearly derived from the cherts of the underlying (Zechstein) Kapp Starostin Formation. Although Orvin postulated a Cretaceous age, the Early Triassic (Scythian) age accepted here is based on lithological correlation (Challinor 1967) with the Vardebukta Formation of the Central Basin (defined at Festningen). It is also consistent with the generalisation by Challinor (Buchan et al. 1965, p. 50) that in Oscar II Land the Triassic strata progressively lose their higher units from south to north.

9.3

Late Paleozoic strata of Oscar II Land (Biinsow Land Supergroup)

Late Paleozoic rocks in this part of Spitsbergen occur in two belts (Fig. 9.2). The m a i n exposures of P e r m i a n rocks are in Broggerh a l v o y a a n d a line extending southeastwards to E k m a n f j o r d e n and

159

N o r d f j o r d e n . A less extensive zone occurs within the Tertiary folda n d - t h r u s t belt, with exposures of C a r b o n i f e r o u s a n d P e r m i a n rocks trending roughly N-S from the eastern end of St J o n s f j o r d e n south to T r y g g h a m n a / Y m e r b u k t a on the n o r t h side of Isfjorden, a n d thence into Nordenski61d L a n d at Festningen ( K a p p Starostin). T h e section at Festningen affords almost complete exposure o f strata f r o m Early C a r b o n i f e r o u s t h r o u g h Early Cretaceous. A d v a n t a g e of this was taken by earlier workers which resulted in the s t a n d a r d stratigraphic description for those intervals in Svalbard. The section was described a n d m e a s u r e d in great detail by H o e l & Orvin (1937). As the n o m e n c l a t u r e used there is the same as for Oscar II L a n d , but different f r o m that in southern Spitsbergen, the Late Paleozoic rocks o f Nordenski61d L a n d will be treated here r a t h e r t h a n in C h a p t e r 10. T h e lower part o f the Gipsdalen G r o u p (approximately Carboniferous) is k n o w n mainly from B r o g g e r h a l v o y a a n d southwestern Oscar II L a n d (St J o n s f j o r d e n a n d T r y g g h a m n a areas). As n o c o m m o n stratigraphic names have been applied across the region, each area is described separately.

9.3.1

Tempelfjorden Group

Kapp Starostin Formation. This f o r m a t i o n is approximately 200 m thick in Oscar II L a n d (Fig. 9.2), w h e r e it is similar to exposures further east. It contains u n i f o r m siliceous limestones and cherts and a rich b r a c h i o p o d a n d b r y o z o a n fauna. H o w e v e r , it is typically s a n d y a n d glauconitic at the top as elsewhere.

9.3.2

Dickson Land Subgroup (Gipsdalen Group)

This u p p e r part of the Gipsdalen G r o u p as defined in the Central Basin ( C h a p t e r 4) represents a laterally extensive depositional unit covering central a n d western Spitsbergen. Exposures in Oscar II L a n d are b r o a d l y similar to those in central Spitsbergen. It comprises two formations.

Gipshuken Formation. The G i p s h u k e n F o r m a t i o n is approxim a t e l y 146m thick w h e r e it is exposed on B r o g g e r h a l v o y a (Fig. 9.1). T w o m e m b e r s are recognized (at Ny-Alesund): an upper dolostone member (60 m) and a (lower) Kloten Breccia (80 m). The latter is u n i f o r m a n d extensive, and p r o b a b l y resulted f r o m solution collapse at the edge o f a large evaporate basin lying to the southeast, as at G i p s h u k e n itself. W o r d i e k a m m e n Formation. The f o r m a t i o n comprises two m e m bers in Oscar II L a n d (the same u p p e r two m e m b e r s of the replaced Nordenski61dbreen F o r m a t i o n ) . Tyrrellfjellet Mbr, Cutbill & Challinor (1965) described three units in this member. At the top the Ki~rfjelletBeds which are approximately equivalent to limestone B (now Finlayfjellet Beds) of the Central Basin. It is of incompetent thinly-bedded to laminated dolostones. The middle unit is an unnamed dolostone sequence; and the lower unit is the Brucebyen Beds - a bituminous fusuline coquina overlying sandy limestones with a thin conglomerate (up to 8 m) at its base. A local unconformity cuts out the Brucebyen Beds at Scheteligfjellet. The MorebreenMbr 115 140 m of Cutbill & Challinor (1965) is equivalent to the Cadellfjellet Formation. Up to 140 m thick on Broggerhalvoya, it consists equally of interbedded dolostones and limestones. Deposition probably occurred on a quiet marine shelf with high salinity. Although no macro fossils have been recorded, fusulinids indicate a Late Moscovian-Gzelian age. No lithological subdivision is possible, but the Gerritbreen and Jotunfonna beds present to the east can be traced on the basis of fusulinid zonation. The topmost beds contain Waeringella usvae zone fossils of Gzelian age. The dolostone is buff-coloured, generally thick-bedded, blocky and with a micritic or silty texture. It commonly contains nodules of chert. Grey limestones occur interbedded with the dolostones. They are generally fairly pure biomicrites with abundant fusulinids and bryozoans, but no macrofossils. Beds are occasionally sandy at the base and chert nodules are common. Massive beds of grey, poorly bedded, stylolitic micrite occur at the top of the formation in the north of Broggerhalvoya. Faunas and age. Two sets of beds were distinguished on the basis of fusulinid zones further east by Cutbill & Challinor.

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The Gerritbreen Beds. These are carbonates containing the W. usvae zone fauna, occurring at the top of the formation in Broggerhalvoya, where they are about 83 m thick. They pass laterally onto the Nordfjorden Block with some thinning and form part of the Kapitol Member. Within the St Jonsfjorden Trough, the beds are cut out rapidly to the south by the Permian unconformity and at St Jonsfjorden, the Permian Tyrrellfjellet Fm rests directly on the TSrnkanten Fm. The Jotunfonna Beds. These are distinguished by the presence of the earlier Wedekindellina zone fauna and are about 60m thick in Broggerhalvoya. They thin slightly to the east and pass laterally into the Kapitol Mbr. They are also cut out to the south by the basal Permian unconformity. No benthic macrofauna has been recorded, only bryozoans and foraminifers. Cutbill (pers. comm.) listed the following: upper W. usvae zone (Gzelian) species from the top of the formation at Scheteligfjellet: Waeringella usvae, Quasifusulina longissima, Triticites sp. A, 'Schubertella' sp., Montiparus montiparus, Protricitites ovatus, Pseudoendothyra sp. Other species, representative of the lower W. usvae zone (Kasimovian) and the upper Wedekindellina zone (Late Moscovian), occur lower down in the unit. The Morebreen Mbr can therefore be correlated with the Jotunfonna and Gerritbreen beds in Billefjorden, as well as the lower part of the Kapitol Mbr of the Nordfjorden Block. The W. usvae zone correlates with the Gzelian and Kasimovian stages of the Russian Platform, so the unit is of Late Moscovian-Gzelian age.

9.3.3

Charlesbreen Subgroup (Gipsdalen Group)

This c o m p r i s e s the lower f o r m a t i o n s o f the G i p s d a l e n G r o u p in the west (Fig. 9.2) a n d is a p p r o x i m a t e l y e q u i v a l e n t to the C a m p bellryggen S u b g r o u p o f the C e n t r a l Basin. A C h a r l e s b r e e n G r o u p was i n t r o d u c e d by Dineley (1958) for the St J o n s f j o r d e n strata a n d was e x t e n d e d also to include the B r o g g e r h a l v o y a f o r m a t i o n s as a s u b g r o u p by S K S (1996). It c o m p r i s e s two pairs o f e q u i v a l e n t f o r m a t i o n s thus:

St Jonsfjorden and Isfjorden T~rnkanten Fm Petrellskaret F m

Broggerhalvoya Scheteligfjellet F m Broggertinden Fm

Scheteligfjellet Formation. This f o r m a t i o n consists o f c a r b o n a t e s , calcareous s a n d s t o n e s a n d c o n g l o m e r a t e s f o r m i n g sequences u p to 150 m thick (Fig. 9.5). It was d e p o s i t e d in Early to M i d - M o s c o v i a n time, a n d represents a m a r i n e transgression over terrestrial rocks o f the B r o g g e r t i n d e n F o r m a t i o n a n d Billefjorden G r o u p . It c o n t a i n s a varied f a u n a i n c l u d i n g fish remains. Definition. The Scheteligfjellet Fm is a distinctive 150m thick unit recognized only in western Broggerhalvoya. It is cut out eastwards by the Pretender Fault. Gobbett (1963) introduced the term Scheteligfjellet Beds for the Middle Carboniferous strata lying beneath the Cyathophyllum Limestone. Cutbiil & Challinor (1965) redefined the Scheteligfjellet Mbr as part of the Nordenski61dbreen Fm occurring only in Broggerhalvoya and coeval with the T~rnkanten Fm of Central Oscar II Land. Their member is here

Fig. 9.5. Fence diagram show the stratigraphic relationships within the St Jonsfjorden Trough (From Cutbill & Challinor 1965).

upgraded to formation status in line with the replacement of the Nordenski61dbreen Fm. The 'Leinstranda Fm' described by Barbaroux (1968) is probably equivalent to the Scheteligfjellet Fm. The type section is at Scheteligfjellet. The formation lies conformably beneath the Jotunfonna Beds of the Morebreen Mbr, the top being marked by a downward passage from rather pure carbonates to interbedded cherty carbonates, calcareous sandstone and some conglomerates which are red in part. The lower boundary is an unconformity marked by a basal conglomerate. It overlies Billefjorden Gp sediments to the west of the Kvadehuken Fault, and the red clastics of the Broggertinden Fm to its east. Lithologies. The formation comprises a distinctive, but somewhat heterogeneous, unit of carbonates, calcareous sandstones and breccias, with a basal conglomerate. Shelf carbonates make up the bulk of the formation (75%). They are generally grey or dark grey micrites or biomicrites, commonly with interbedded calcareous sandstones. Holliday (1968) noted a ~ 3 m coral biostrome occurring locally above the basal conglomerate: it is almost completely dominated by the species Chaetetes radians Fischer and Campophyllum kiaeri Holtedahl, with rare Syringopora sp., which are usually in positions of growth and built on top of each other (this is the 'coral limestone' of Holtedahl 1913). On Ki~erfjellet and northern Kulmodden, the formation contains breccias up to 50 m thick, comprising fragments of grey and yellow-weathering dolostone and limestone up to 10 cm across. The mass splits into several layers when traced laterally. The breccias are probably of intraformational origin, formed by erosion of the underlying beds, but a solution mechanism cannot be ruled out. Greenish-grey or reddish calcareous sandstone interbeds are the distinctive feature of the formation and occur throughout, making up 15% of the total. Red and green shales and siltstones occur with sandstones near the base of the formation. The base of the formation is marked by a conglomerate 0 8 m thick, that fills in topographic irregularities in the pre-Moscovian surface. It is largely quartzose, but with more variable clasts than the underlying Billefjorden Group conglomerates, with indications of channelling and reworking of sediments. Beds and lenses of black laminated limestones, red shales and red or green sandstones occur. The matrix is calcareous and shows signs of algal binding (Holliday, 1968). Palaeontology and age. The formation contains an abundant marine fauna, including brachiopods, fusulinids, corals, crinoids, bryozoans, gastropods, trilobites and fish. Holtedahl (1911, 1913) first described a rich Moscovian fauna from Braggerhalvaya, collected from limestones and conglomerates at the base of the formation. The brachiopod fauna is of general 'Middle Carboniferous' character and resembles that of the Minkinfjellet Mbr in Billefjorden and the TSrnkanten Fm of St Jonsfjorden (Gobbett 1963). The fusulinids are typical of the Wedekindellina zone in the upper part of the member and the Profusulinella zone lower down as defined by Cutbill & Challinor (1965). This implies an Early to Mid-Moscovian age for the formation, and strongly supports the correlation with the Minkinfjellet Fm.

Braggertinden Formation, 350 m. T h e B r o g g e r t i n d e n F o r m a t i o n is a variable sequence o f s a n d s t o n e s , c o n g l o m e r a t e s a n d c a r b o n a t e s f r o m B r o g g e r h a l v o y a a n d n o r t h e r n Oscar II L a n d (Fig. 9.3). It is correlated with the E b b a d a l e n F o r m a t i o n o f the Billefjorden area (Cutbill & C h a l l i n o r 1965). It occurs only to the east o f the K v a d e h u k e n Fault. T h e s a n d s t o n e s are generally flaggy a n d micaceous, a n d are o f variable c o l o u r f r o m red a n d b r o w n to yellow. I r o n is c o m m o n a l t h o u g h i r o n s t o n e b a n d s are rare. D e p o s i t i o n p r o b a b l y o c c u r r e d in a fluvial e n v i r o n m e n t . N o m a r i n e f a u n a have been r e c o v e r e d a n d the o t h e r f a u n a (including fish remains) are n o t age-diagnostic. H o w e v e r , the f o r m a t i o n is generally r e g a r d e d as being o f B a s h k i r i a n age. Definition. The formation is well exposed at several localities on Broggerhalvoya. The type section is at Broggertinden, where it is 361 m thick. The formation is absent to the west of the Kvadehuken Fault, where Billefjorden Gp sandstones occupy an analogous position. The formation lies concordantly beneath limestones of the Scheteligfjellet Mbr. The boundary is an unconformity marked by the basal conglomerate of the overlying member, dividing the largely carbonate lithologies above from arenaceous ones below. The base is marked by a sharp unconformity, overlying pre-Devonian mica-schists. Nowhere does the formation rest on Early Carboniferous Billefjorden Gp strata, which are present in Broggerhalvoya only to the west of the Kvadehuken Fault.

C E N T R A L WESTERN SPITSBERGEN Two lithological units are present in the type section at Broggertinden. The Upper Mbr, about 185m thick, comprises sandstones with conglomerates and rare limestones, e.g. at Ki~erfjellet. The Lower Mbr consists of about 163 m of conglomerates with few finergrained interbeds. Lithologies. The formation consists predominantly of sandstones (45%) and conglomerates (45%). Fine, medium and coarse-grained sandstones occur throughout the formation, interbedded with the conglomerates. They are commonly flaggy and micaceous, in places shaly. Iron is abundant, and hematite cement occurs in some beds. They are generally red or brown, but white and grey beds are found. Yellow, red and brown conglomerates occur throughout, predominating in the lower part. Clasts are rounded and 2-3 cm across. They consist of quartzite and chert derived either from pre-Devonian rocks or secondarily from the Orustdalen Formation. The matrix is sandy. Red shales occur interbedded with the sandstones and conglomerates. A thin ironstone occurs near the top of the formation at Broggertinden. At Kia~rfjellet, the middle of the upper part contains yellow shaley dolomites, conglomeratic limestones and grey, blocky calcarenite. One such carbonate bed contains rare fossils. Palaeontology and age. Poorly preserved fish fragments were found in the sandstones in the Scheteligfjellet section by Orvin (1934) who first supposed a Devonian age; otherwise the clastic facies appears to be unfossiliferous. The limestones on Kia~rfjellet contain poorly preserved brachiopods, crinoids and fusulinids which are certainly of Carboniferous age. Thiedig (1988) reported mid-Carboniferous microfossils in limestones associated with the red beds. As the formation lies below the Moscovian Scheteligfjellet Member and resembles facies of the Ebbadalen Formation it is assumed to be of Bashkirian age.

Tfirnkanten Formation. P r e s e n t along the I s f j o r d e n c o a s t o f Oscar II L a n d , the Tgtrnkanten F o r m a t i o n is a u n i t u p to 250 m thick o f m a i n l y q u a r t z arenites w i t h m i n o r c o n g l o m e r a t e , shale a n d limestone. C a l c a r e o u s n o d u l e s a n d desiccation cracks c a n be o b s e r v e d in places, a n d the s a n d s t o n e s are c o m m o n l y r e d d e n e d . T h e limestone b a n d s c o n t a i n a varied f a u n a w h i c h indicates Early a n d M i d - M o s c o v i a n ages. D e p o s i t i o n was w i t h i n a c o a s t a l / i n t e r t i d a l e n v i r o n m e n t w i t h b o t h fluvial a n d m a r i n e c o n d i t i o n s represented. Definition. Dineley (1958), in his description of the 'Charlesbreen Group', distinguished the higher red sandstone and conglomerate unit as the Tfirnkanten Sandstone. It was defined as The Tgtrnkanten Fm by Cutbill & Challinor (1965). The formation is the lateral equivalent of the Scheteligfjellet Fm of Broggerhalvoya (see above). The type section is on Tfirnkanten, where the formation is 251 m thick. The sequence reappears in the south of Oscar II Land at Trygghamna and south of Isfjorden at Orustdalen where 253 m are present below the Permian Tyrrellfjellet Mbr. Further south in Bellsund, the formation is cut out by prePermian erosion and the Tyrrellfjellet Mbr limestones rest directly on Early Carboniferous Billefjorden Gp sandstones of the Vegard and Orustdalen fms. The upper boundary is an unconformity beneath the Permian Wordiekammen Fm limestones which appear to cut down into the T~trnkanten Fm sandstones. These have been leached at the top and bright yellow limonite coats the bedding surfaces and joints. The lower boundary is at the base of the lowest massive sandstones under which lie the soft red shales of the Petrelskaret Fro. Lithologies and division. The formation consists of arenites (80%), conglomerates (5%), thin shales (10%) and limestones (5%). Massive, mature quartzose red and white coloured sandstones and grits, which are quartzitic or calcareous in places, form the bulk of the formation. Feldspar is rare. Cross-bedding is common, generally on a small scale, with foresets inclined at a low angle. Asymmetrical and oscillation ripple marks also occur, but there appears to be no preferred orientation. There is syn-sedimentary contortion near the top of some sandstone beds. The sandstones have sharp bases, and commonly grade upwards into finer sediments. The beds are occasionally conglomeratic at the base, with vein-quartz pebbles. Intraformational conglomerates are common, and may also contain rolled fossils. Thin marls or shales of a variety of colours occur regularly interbedded with the sandstones. They often contain small calcareous nodules scattered in bands. Polygonal desiccation cracks commonly affect the thin shales between the sandstone beds, ranging in diameter from 2-30 cm and penetrating downwards for up to 60 cm. There are several bands of thin grey limestone, commonly containing marine fossils, in the middle and upper part of the formation. They contain varying amounts of silt and sand and in places grade into coarse sandstone. Dineley & Garrett (pets. comm.) have recognized three major cyclothems within the formation at St Jonsfjorden, separated by two distinct

161

marine bands. At the base of each are massive quartzites which are overlain by calcareous grits and sandstones, conglomerates and thin shales with a marine band at the top. The latter is several metres thick and consists of poorly sorted sandstone with trace fossils which passes upwards into shale followed by limestone with marine fossils, then more shale then finally finegrained sandstone. The upper cyclothem is incomplete, and is represented by the highest massive and thin-bedded quartzites with thin red and brown shales exposed beneath the Permian unconformity. It has the Tfirnkanten marine band (c. 4 m thick) at its top, below which lie about 21 m of mottled calcareous sandstones and conglomerates containing at least one fossiliferous sandy limestone. These are underlain by a 44 m thick unit of massive red and white quartzose sandstones and quartzites. The lower cyclothem is similar: its top is defined by the fossiliferous Robertsonfjellet marine band (7.5 m), underlain by 20m of calcareous sandstone and 68m of red calcareous and quartzose grits, with massive red and white quartzites at the base. Palaeontology and age. varied marine faunas are common in the limestones, especially in the upper part of the formation. The faunas of the two marine bands are distinctive and consist predominantly of one species of brachiopod (a spiriferid in the Robertsonfjellet marine band and a large chonetid in the T~rnkanten marine band), with other brachiopods, crinoid ossicles, echinoid spines and rare coral fragments, trilobites and molluscs. Other limestone beds yield corals, brachiopods and crinoids. Rare lingulids are present at some horizons and fragmentary plant remains occur locally. The brachiopods compare closely with those of the Scheteligfjellet Formation of Broggerhalvoya (Gobbett 1963; Dineley & Garrett 1950, and CSE), suggesting that the unit is probably of Early and Mid-Moscovian age.

PetreHskaret Formation, 350 m. This f o r m a t i o n consists m a i n l y o f shales a n d m u d s t o n e s , c o m m o n l y p u r p l e in c o l o u r b u t also black a n d even b i t u m i n o u s in places. Also p r e s e n t are t h i n s a n d s t o n e interbeds, i r o n s t o n e b a n d s a n d rare e v a p o r i t e beds. T h e age o f the f o r m a t i o n is e s t i m a t e d as Bashkirian, a l t h o u g h the f a u n a is very sparse. D e p o s i t i o n was o n a coastal alluvial plain, m a i n l y fluvial or lacustrine b u t with a m a r i n e influence, especially early o n w h e n m o s t o f the l i m e s t o n e s a n d evaporites were f o r m e d . Definition. The Petrellskaret Fm is a sequence of shales having limited outcrop in Oscar II Land. It was originally described by Dineley (in Gobbett 1963) from St Jonsfjorden. Cutbill & Challinor (1965) gave it formational status and correlated it with the Broggertinden Formation. The type section is on Petrelskardet, St Jonsfjorden (Fig. 9.5). It is present at Orustdalen south of Isfjorden, but is absent around Bellsund owing to Permian erosion. The upper boundary is conformable, at the base of the massive quartzites of the TArnkanten Fm. The base is conformable and marked by a group of hard sandstones, silicified limestones, shales and evaporites 12.5 m thick, below which are dark shales and grey sandstones of the Vegard Fm (Billefjorden Gp). Lithologies. The bulk of the formation (80%) is composed of shales and laminated mudstones, generally purple, but in places black and bituminous, especially in the upper part, where conspicuous bands of ironstone are found. A remani6 band of ferruginous grit, 23 m thick, containing phosphatic nodules, clay pellets, rare quartz pebbles, fish scales, bones and teeth occurs near the top of the formation. There are thin sandstone interbeds, with rare intraformational conglomerates. The shales are occasionally marly towards the base of the formation and calcareous nodules occur. At the base are grey silicified limestones and evaporites interbedded with hard sandstones and shales. Light-coloured sandstone beds, generally quite thin, occur throughout, forming about 15% of the formation. They are sharply defined, commonly with erosive bases and are irregular in thickness or lenticular. They become finer upwards. Clay intraclasts are locally present in the basal layers. A thick white quartzite occurs 90 m below the top. Evaporites are a minor constituent of the sequence, occurring as thin intercalations at the base and as a gypsum band about 65 m below the top. Palaeontology and age. Fossils are rare in this formation. On Petrellskaret, indeterminate corals, resembling cyathophyllids and ?Syringoporaare found in the limestones near the base, and fish scales, bones and teeth occur in the remani6 grit near the top. As the formation lies below sediments of Moscovian age and above the Serpukhovian Vegard Fm, it is probably of Bashkirian age. 9.3.4

Billefjorden Group

T h e Billefjorden G r o u p in w e s t e r n Spitsbergen consists o f the V e g a r d a n d O r u s t d a l e n f o r m a t i o n s , u p to 1 1 2 0 m thick, d e p o s i t e d

162

CHAPTER 9

in the St J o n s f j o r d e n T r o u g h , w h i c h appears to have been isolated f r o m the rest of Svalbard in Early C a r b o n i f e r o u s time. P r e - P e r m i a n uplift a n d erosion has r e m o v e d some of the V e g a r d F o r m a t i o n and later C a r b o n i f e r o u s sediments in m a n y areas. The full extent of the t r o u g h is not known; but it stretched, at least, f r o m B r o g g e r h a l v o y a to Bellsund The eastern m a r g i n was the N o r d fjorden Block. T w o f o r m a t i o n s were recognized in western Spitsbergen by Cutbill & Challinor (1965) in the Culm of N a t h o r s t (1914; 1920), H o l t e d a h l (1912) and Orvin (1940). These are the (upper) Vegard F o r m a t i o n , consisting of thinly-bedded sandstones and shales; a n d the (lower) O r u s t d a l e n F o r m a t i o n o f coarse sandstones and conglomerates.

Vegard Formation, 358 m. The V e g a r d F o r m a t i o n consists of sandstones with c a r b o n a c e o u s shales a n d subordinate conglomerate. It is a fluvial unit o f p o o r l y constrained age as f a u n a are sparse, but it is generally regarded as Serpukhovian. Definition. This is a formation of sandstones and shales which is 358 m thick in the type section in Orustdalen in Nordenski61d Land. It was first described in Oscar II Land by Dineley (1958), who divided the 'Culm' into two formations. Cutbill & Challinor (1965) extended this upper formation southwards to Nordenski61d Land, where maximum thicknesses occur. The upper boundary in the type section is sharp, but conformable, and is marked by an abrupt upward lithological change from sandstones with interbedded shales to the beds of the basal Petrellskaret Fm (Gipsdalen Gp). The latter consists, at its base, of silicified limestones and evaporites interbedded with hard sandstones and shales (see above). Elsewhere, however, later Carboniferous erosion has resulted in removal of the top of the formation and an unconformity with the Permian Wordiekammen Fm limestones. The base is conformable above massive sandstones of the Orustdalen Fm. Lithologies. Light grey, white and locally reddish, thinly-bedded/flaggy or blocky sandstones are interbedded with dark grey-black carbonaceous shales. The sandstones are generally fine-medium grained, but occasionally coarse-grained, and there are local conglomerate horizons and lenses. Poorly-preserved plant remains are common in both sandstones and shales; the latter may be coaly. Palaeontology and age. Nathorst (1914), in his studies of the Billcfjorden Group, included detailed lists of plants from the 'Culm' of western Spitsbergen. Although the Vegard and Orustdalen fins were not differentiated, on the basis of locality the stratigraphic position of some can be ascertained. He distinguished three separate floras (Nathorst, 1920), of which the uppermost Diabasbukta flora, containing Cardiopteridium nanum, is from the Vegard Fm. However, this flora has not been identified elsewhere. The poor preservation of spores has frustrated palynological studies, and nothing is published on this formation. Hence correlation of the formation is tentative, but if the Orustdalen Fm, below, is of Late Visean to earliest Serpukhovian age (see below), then this formation is probably Serpukhovian. There are lithological similarities, (sandstones and shales with some red beds and thin coals), to the earliest Serpukhovian Hultberget Mbr of the Billefjorden Trough (see Chapter 4), with which it may be contemporaneous (Cutbill & Challinor, 1965). Orustdalen Formation. Sandstones and shales are the predominant constituents of this formation, which varies in thickness up to several h u n d r e d metres. The sandstones are invariably quartz rich but also contain clasts o f m e t a m o r p h i c rock and chert. Plant remains are c o m m o n but coal has only been recorded f r o m a single horizon on Broggerhalvoya where it is k n o w n only west of the K v a d e h u k e n Fault. There are no m a r i n e fossils but the flora indicates a Late Visean or Early S e r p u k h o v i a n age. The f o r m a t i o n represents a fluvial e n v i r o n m e n t on a growing alluvial fan building out from a fault scarp into a m a r i n e basin. Definition. Dineley (1958) divided the 'Culm' in Oscar II Land into two formations. His lower Trygghamna Fm is the equivalent of the Orustdalen Fm of Cutbill & Challinor (1965) which can be traced from Reinodden to Broggerhalvoya. It is 759 m thick in the type section at Orustdalen, thinning to 654 m north of Bellsund and only about 200~50 m at St Jonsfjorden. The upper boundary is conformable with the overlying Vegard Fm. The junction is marked by a change to a thick sandstone sequence with a sudden reduction in shales. The base is marked by an angular unconformity above pre-Devonian schists. Locally there are basal conglomerates. Lithologies. They are generally more arenaceous than the Vegard Fm. Monotonous light grey or white, thickly-massively bedded sandstones are

interbedded with thin, black, red or grey shale horizons (up to 20 cm locally). Sandstones are mainly medium-coarse grained and quartzitic, with common cross-bedding and ripple-marks. Lenses and beds of coarse quartz-conglomerate occur, especially within the bottom 50 m and there is a locally developed basal conglomerate (Orvin 1940; Hjelle 1962) that is rich in hematite in places. The conglomerates contain sub-rounded pebbles, not only of white veinquartz, but also of red and black chert and jasper, feldspars, schist and plant fragments up to 5 cm in diameter. They are associated with interbedded sandstones and shales. Thicker (20-40 cm) shales appear downwards, which are usually dark, but are locally grey or red. Plant remains are very common, though they are generally poorly preserved as carbonaceous impressions. There are no coals, except near the base on Braggerhalvoya, where a 3 m thick unit of poor quality coal (ash content 30%), and carbonaceous shale occurs (Orvin 1934). Fairchild (1982) mentioned a 7 cm in-situ coal seam with a 1 cm underclay in the same area and also another rootlet horizon 100 m further up. Palaeontology and age. Nathorst (1914) listed the flora of the Billefjorden Group, including many species which, by inference, came from the Orustdalen Formation. In addition, he distinguished three distinct floras, the lower two of which must be from the Orustdalen Formation (Nathorst 1920). The Hagerup Haus flora is the younger and contains Sphenopteridium norbergii and Thysanotesta sagittula. It is separated from the Camp Millar flora below by beds containing only Stigmariaficoides. The Camp Millar flora is characterized by Adiantites bellidulus, Lagenospermum arberi and Lepidodendron mirabile. However, these assemblages, which are almost certainly pre-Serpukhovian, have not been identified elsewhere. Forbes, Harland & Hughes (1958) noted the similarity of the Hagerup Haus flora to that found east of Festningen and at Billefjorden in the Svenbreen (or possibly the Horbyebreen) Formation which suggested a possible correlation, confirmed in 1982 by Fairchild (see below). Lepidodendron Nordenskidldii, L. heerii, Sphenopteridium norbergii, Adiantites bellidulus and Cardiopteridium ?spetsbergens, found at Billefjorden in the Svenbreen/ Horbyebreen formations, are also recorded by Nathorst from the Orustdalen Formation and Lepidodendron rhodeanum, Lepidodendron robertii and Sphenopteris bifida are common to both the Svenbreen and Orustdalen formations (Cutbill & Challinor 1965). Earlier attempts to describe the palynology of these strata were frustrated by the very poor preservation of microfossils in this western region, probably a result of the Tertiary orogeny. However, one horizon low in the sequence on Broggerhalvoya has yielded spores which indicate a Visean/earliest Namurian age (Fairchild 1982). Lycospora pusilla and small Densosporites are common. Thus the Orustdalen Formation is probably of Late Visean or possibly Early Serpukhovian age and correlates with the Mumien Formation, a correlation supported by its lithology which resembles that of the lowermost member of the Mumien Formation.

9.4

Early Paleozoic rocks

Early publications on this area were few and include H o l t e d a h l ' s (1913) observations and Orvin's (1934) detailed study o f Broggerhalvoya as part o f a t h o r o u g h description of the N y - A l e s u n d coalfield. Post-war research increased greatly beginning with B i r m i n g h a m University expeditions in 1948, 1957 and 1958 (Baker, Forbes & H o l l a n d 1952; Weiss 1953, 1958; Dineley 1958). Structural studies by B a r b a r o u x (1966a, b) and Challinor (1967) followed. The blueschists of Motalafjella were intensively studied after their discovery by C a m b r i d g e parties in 1961 (Horsfield 1972; O h t a 1979, 1985a, 1992; Ohta, Hiroi & Hirajima 1983; Ohta, H i r a j i m a & Hiroi 1986; K a n a t 1984a, b). Ordovician-Silurian fossils were reported by Scrutton, Horsfield & H a r l a n d (1976) a n d by A r m s t r o n g , N a k r e m & O h t a (1986). The rocks, largley Ordovician are described in two distinct units: the Bullbreen G r o u p and the Vestg6tabreen Complex.

9.4.1

Bullbreen Group (Harland, Horsfield et al. 1979)

Different stratigraphic schemes have been proposed for the rocks, n o w k n o w n to be of Early Paleozoic age a n d occurring mainly as outliers in the area south of St J o n s f j o r d e n (Motalafjella t h r o u g h Holmesletfjella across Bullbreen to Bulltinden) and n o r t h of the

CENTRAL WESTERN SPITSBERGEN fjord at Ankerfjella, Kaffioyra a n d Sarsoyra. T h e successive cont r i b u t i o n s are r e c o u n t e d a n d a unified n o m e n c l a t u r e is p r o p o s e d . Holtedahl (1913, p. 57) reconnoited the southeast shores of St Johnsfjorden and noted a conglomerate with boulders matching, for example, his Alkhorn limestones. This was most probably at Bulltinden, west of Bullbreen. In 1959 from a temporary anchorage at Copper Camp, Harland noted the extensive flysch sequence of calcareous argillites and polymict conglomerates referring them to his Holmesletfjella unit (1960), although mistakenly placed earlier than the Comfortlessbreen Group. Wilson & Harland (1964), Winsnes (1965) and Flood, Nagy & Winsnes, 1G, (1971) related the conglomerate to the Comfortlessbreen tilloids but the stone content did not match. In 1968 Horsfield & Harland suspected fossils from limestone clasts and in 1969 Horsfield collected fossils from the conglomerates in Motalafjella. The fauna was tentativelly identified with late Ordovician or early Silurian forms. In 1971, Harland revisited the locality and made a small collection from a penecontemporaneously slumped limestone within the conglomerate. The two collections together suggested a Wenlock or Ludlow age (Scrutton, Horsfield & Harland 1976) where the scheme in Harland et al. (1979) was used because it had been submitted in 1975. Horsfield (1972) in describing the Vestg6tabreen Complex metamorphism described all the later rocks as the Bulltinden Fm (Harland, Horsfield et al. 1979). As part of a stratigraphic scheme for the whole of Oscar II Land, they made the Bulltinden conglomerate a member within the Homesletfjella Fm, and placed the underlying strata-mainly limestones in another formation the Motalafjella Fm. Ohta (1979) followed Horsfield (1972) his paper being in the same publication as Harland et al. (1979). Ohta, Hiroi & Hirajima (1983) identified the contact between the metamorphic complex and showed it to be an overturned unconformity which they mapped. They used the name Bulltinden Formation for the conglomerate and the older basal limestone above the complex, supposedly following Harland et al. (1979) for this usage. Armstrong, Nakrem & Ohta (1986) reported significant conodont studies which suggested a Caradoc or earlier age for the basal limestone and also for a limestone lens within the overlying sandstone and shale member. The overlying boulder conglomerate with slumped olistostromes were suggested to be of Early Silurian age. These three members were of the Bulltinden Fm. Kanat & Morris (1988) in describing this general succession in the St Jonsfjorden area followed Harland, Horsfield, Manby & Morris (1979) referring to the two formations Holmsletfjella (above) and Motalafjella (below) and comprising the Bullbreen Group. They described the sequence in detail for the first time. Their scheme is followed here except for the Bulltinden conglomerate member. It has proved to be the most conspicuous unit, occasionally of great thickness, has been frequently referred to in the literature, was first noted with fossils, later yielding a distinct fauna. Therefore it was upgraded to formation rank and the two members beneath it were transferred into the Motalafjella Fro. The proposal is thus, details follow.

BuUbreen Gp Holmesletflya Fm (probably Silurian) Bulltinden (conglomerate) Fm (Early Silurian) Motalafjella Fm (Late Ordovician)

HolmesletfjeUa (slate) Formation, first identified as W6, by W i l s o n in 1958, the e p o n y m o u s m o u n t a i n was revisited a n d n a m e d ( H a r l a n d 1960) b u t in m i s t a k e n order, s o m e w h a t rectified by H a r l a n d e t al. (1979). T h r e e m e m b e r s were described ( K a n a t & M o r r i s 1988). Siliceous slate mbr, 20m (BH6 of Kanat & Morris) is best exposed in northern Holmesletfjella, is a friable siliceous slate, upper contact not known. Elongate irregular dark features were interpreted as trace fossils. Lower boundary is sharp and conformable . Sandstone slate mbr, 100m+ (BH5 of Kanat & Morris) exposed in Holmesletfjella and Motalafjella, Bulltinden, Ankerfjella etc. interbedded calcareous sandstones (65%), slates (25%) and immature and impersistent conglomerate horizons (10%) show cross bedding, conspicuous from a distance due to colour-banding (grey to buff) and reveals fiat-lying nearisoclinal folds giving a first impression of much greater thickness. The base is transitional with decrease in conglomerate content. Slate Mbr, 30 m (BH4 of Kanat & Morris) is black, slightly calcareous and of similar extent to the above member. Its base is sharp. Bulltinden (conglomerate) Formation, 10 60 m (BH3 o f K a n a t & M o r r i s ) is m a i n l y a p o l y m i c t c o n g l o m e r a t e with clasts r a n g i n g in

163

size f r o m granules u p w a r d s t h r o u g h b o u l d e r s to s l u m p e d olistost r o m e s , a n d is variably i n t e r - b e d d e d with s a n d s t o n e s a n d slates similar to the Holmesletfjella F o r m a t i o n . It has been described in detail by K a n a t & M o r r i s (1988) with clasts o f l i m e s t o n e 4 0 % , schist 2 5 % , s a n d s t o n e 2 0 % , d o l o s t o n e 10% c o n g l o m e r a t e 5 % , dolerite < 1 % . T h e clast lithologies m a t c h either those o f the Bullbreen G r o u p or the m e t a m o r p h i c s o f the V e s t g 6 t a b r e e n C o m p l e x ; s o m e o f the l i m e s t o n e s m i g h t be V e n d i a n . Fossils were first noted in the limestone clasts and a distinct coral, gastropod, bryozoan, echinoid fauna was collected from a 100+m 3 olistostrome (Scrutton, Horsfield & Harland 1976) estimated to be of late Llandovery to Wenlock age. Work on conodonts confirmed an Early Silurian age (Armstrong, Nakrem & Ohta 1986). Harland's opinion was that this slumped mass, unlike some conglomerate clasts was penecontemporaneous. The base of the formation is a sharp erosive sedimentary contact.

Motalafjella (slate and limestone) Formation, 2 6 0 m ( H a r l a n d , Horsfield e t al. 1979). This f o r m a t i o n newly includes the two lower m e m b e r s f r o m the Holmesletfjella F o r m a t i o n o f K a n a t & M o r r i s w h i c h is d i v i d e d here into t w o units, the lower o f w h i c h was classified by t h e m with the V e s t g 6 t a b r e e n C o m p l e x . T h e r e are t h u s five m e m b e r s . Slate Mbr, 10 m (BH2) a black ferruginous slate (with bands of subhedral pyrite. The base is transitional. Sandstone-slate Mbr, 150m (BH1 of Kanat & Morris) best seen in western Motalafjella, but also Holmesletfjella, Ankerfjella and in Bulltinden, where the upper contact is under the Bulltinden conglomerate. Within the sandstones up to 10% of conglomerates may occur and both sandstone and conglomerate may give way to slate. The carbonate content here is greater than in the Holmesletfjella sandstones. The lower contact is sharp but conformable. Limestone Mbr 100 m (BM1 of Kanat & Morris). This is predominantly of limestone which forms the peak of Motalafjella and is only 3 m at Ankerfjella. a gritty (up to 30% detritus) fossiliferous (crinoid stems and coral fragments) cryptocrystalline grey, buff-weathering, limestone. This limestone seems to be the source of the fossiliferous clasts in the Bulltinden conglomerate. It was also the source of the Caradoc or even Arenig conodonts described by Armstrong, Nakrem & Ohta (1986). The (somewhat tentative) conclusion of their study combined with the macrofossil evidence is for a Caradoc age. Conglomerate slate Mbr (BM1 of Kanat & Morris). A thin member or bed at the base of the limestone is indicative of a basal conglomerate. Dolostone Mbr, 0 - 2 0 m (VOD of Kanat & Morris). This distinctive orange-weathering dolostone is consistently found below the Motalafjella unit (BM1) where it is in contact with the Vestg6tabreen Complex, except at Ankerfjella and Bulltinden where it is in contact with the Comfortlessbreen Group. Ohta, Hiroi & Hirajima (1983) demonstrated a basal unconformity contact with the complex and limestone and metamorphic fragments in the succeeding dolostone. The rock is a coarsely crystalline grey siliceous dolostone with 5% or even 10% of chromium phengite (mariposite) weathering to a distinctive orange. It has the fabric of a thrust breccia in places. The high magnesium, chromium and nickel content suggest a carbonated metasomatized ultrabasic rock, associated with the Vestg6tabreen Complex. The conclusion here is that, from its consistent occurrence at the base of the Motalafjella Formation and from the description of Ohta et al. it belongs to that formation but it has been selected as a thrust horizon. This would reconcile the apparently conflicting observations; but it leaves unresolved the contact at Ankerfjella, which while clearly a thrust contact may yet have been unconformable there also. Some mineralization may well have been selected by the thrust surface. Ferruginous waters pour down from a spring in the scree on northern Motalafjella at about this horizon, east of Copper Camp. The mineralization could well be Paleogene (see Chapter 20). Sarsoyra Formation, 450 m. This f o r m a t i o n is seen in c o n t i n u o u s white cliffs w h i c h b o u n d the S a r s o y r a plain to the east. W i t h i n the S a r s o y r a plain leading o u t to the n a r r o w a n d shallow passage at S a r s t a n g e n are scattered o u t c r o p s with a N - S o r i e n t a t i o n investigated by C S E as follows. C. B. W i l s o n suggested a h o r s t structure, W . T . Horsfield n o t e d s l u m p e d blocks o f the n e i g h b o u r ing T e r t i a r y facies related to it a n d t h a t all were a l l o c h t h o n o u s . H a r l a n d first suggested a step-faulted s t r u c t u r e at the m a r g i n o f the graben, w i t h fault scarps f r o m w h i c h blocks slipped a w a y in a

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CHAPTER 9

rapidly accumulating sedimentary sequence. On this basis some of the larger outcrops would be in s i t u horsts. From further investigation in 1992 he found it difficult to fit the various exposures into a systematic pattern of outcrop or strike. The original idea of strips of rock units could be ruled out, nor did it seem likely that the larger masses could have slipped off fault scarps. They were too large and internally coherent. Nearly every exposure was associated with tectonic breccias. It therefore seemed most likely that the area contains disoriented slices in a large-scale melange strike-slip zone. The lithologies include unsorted clast-supported conglomerates and breccias with pebbles up to 15 cm of white quartzite and vein quartz, finely bedded sandstone to siltstone and psammitic schists. There were also units of dolomitic marble (some of reddish tint) these were generally brecciated. The quartzite and dolostone facies were closely associated. The age of these rocks has been debated as between Carboniferous or Silurian. The earlier age was suggested from a pebble (in a conglomerate in the formation) which contained a lykophyllid coral. The conglomerate was first taken as part o( the Bullbreen Group (see below) by Scrutton et al. (1976). However, C. L. Forbes suggested that a Late Paleozoic age was just as likely. In any case the formation does not have to be the age of its constituent pebbles. Therefore a Carboniferous or possibly Permian age was then preferred. However the new age determination by Makanjev (pers. comm. in Ohta et al. 1995) supports the original opinion of Scrutton et al. (1976).

Aavatsmarkbreen Formation, 600 m. This formation comprises a thick succession of dark grey phyllite, volcanites, psammites and subordinate carbonate. It is isoclinally folded and thickness is difficult to estimate. The lower boundary is not exposed but a transition by alternation with facies of the underlying formation is likely. Three informal divisions have been suggested (Harland, Hambrey & Waddams 1993): (3) c. 300-400 m of highly deformed grey and black phyllite, with thin black marble, white marble, sandy dolostone and quartzite interbeds; (2) 6 - 1 0 0 m of dark green black slate with some quartzite beds At Snippen (south of the Annabreen Formation section) there are soft light green and purple banded shales. (1) c. 400m of dark phyllite and black limestone with thin conglomerate and pink psammite interbeds. Whereas Harland et al. (1993) took this to be the top formation of the Comfortlessbreen Group and of probable Ediacara age, Ohta et al. (1995) with further evidence identified the sequence as belonging to the Bullbreen Group and so of Ordovician to Silurian age. This revision is followed here. 9.4.2

Vestg6tabreen Complex

On Cambridge expeditions in 1958 C. B. Wilson noted high-grade metamorphic rocks in the Eidembreen moraine, D. G. Gee in 1962 located their source showing the presence of glaucophane schists at Motalafjella. Horsfield worked in the area from 1968 (1972) when he showed isotopically that the metamorphism was Paleozoic, probably Ordovician (i.e.c. 470 Ma) and he suggested a subduction zone. These finds led to further mineralogical work e.g. Ohta (1979), Kanat (1984a, b), Ohta, Hirojima & Hiroi (1986) and Kanat & Morris (1988). Age of the Complex. Motalafjella is also noteworthy for its Ordovician and Silurian fossils (see 9.6.1 and 14.4.4) which show the complex to have been metamorphosed not later than Caradoc time and further deformed and thrust in late or post-Silurian time and part at least in Paleogene time. Subduction models have been proposed which if valid would have to reflect an early to midOrdovician Eidembreen event. The age of the protoliths is unknown. The basic igneous composition might match that of the Early Varanger volcanics The limited exposure in only three mountain inliers gives no regional handle to speculate further. These would be from the Lovliebreen Formation suggested by Harland, Hambrey & Waddams (1993) and by Ohta e t al. (1995) which authors differ as to to its age.

Structure of the Complex.

The Vestg6tabreen Complex is closely associated with the Bullbreen Group and crops out in four mountains: Motalafjella, two spurs of Holmesletfjella, north and south of upper Hydrografbreen (formerly Skipperbreen), and Bulltinden. A further outcrop, a distinct klippe of Bullbreen strata occupies the top of Ankerfjella north of St Johnsfjorden. All these outcrops appear to be part of a single folded thrust unit in which the rocks are overturned, so that the OrdovicianSilurian Bullbreen rocks dip beneath the complex in the limbs of a west-dipping overturned syncline seen well in the Bulltinden conglomerates. The Vestg6tabreen-Bullbreen unit has been thrust up and over Vendian rocks from the west or southwest. The contact between the Bullbreen Group and the Varanger groups is not well exposed, but is probably everywhere a thrust surface. It is perhaps best seen north of St Jonsfjorden at Ankerfjella where it is almost horizontal. The nature of the contact between the Complex and the younger Bullbreen Group is critical. Ohta, Hiroi & Hirojima (1983) argued for an unconformity (overturned) on the basis of evidence at seven localities where the Motalafjella limestone contains fragments of an older dolostone which it also penetrates. In addition there are clasts of the metamorphic complex. This conglomeratic zone extended 3 to 5 m from its structural upper surface. The limestone contains gastropods. Moreover, fossil bearing limestone pebbles occur still further from the contact. At one locality the conglomerate layers are cross-bedded and confirm that the strata are inverted. K a n a t & Morris (1988) who surveyed the area, including Ankerfjella, were puzzled by the ochre weathering dolostone (their unit VOD) that occurs nearly everywhere at or near the contact of the complex and the Bullbreen Group, and also at Ankerfjella. They placed it within the Vestg6tabreen Complex and to be subject to thrusting. It is thought here more likely to belong to the basal facies of the Motalafjella Formation of the Bullbreen Group, but agreed that some thrusting has taken place along the unconformity surface. There would thus have been a complex history of successive erosion and deposition phases first of metamorphics, then of dolostone, then of limestone followed or accompanied by folding and thrusting in places along this zone. Lenses of the dolostone are found near the contact with the schists and there are some mylonitic textures. The dolostone itself is often rich in metamorphic clasts similar to those of the complex. On Motalafjella the complex is divided into at least two units by a thrust as depicted by Ohta, Hirajima & Hiroi (1986). Moreover, that the whole complex has been subject to penetrative shearing is evident from the ubiquitous schistosity. The thrusting appears to be a part of the (Eocene) West Spitsbergen Orogeny. Five lines of evidence support this conclusion. (i) The whole of the orogen of which this unit is a part, exhibits eastwards or northeastwards verging overfolding and thrusting, including Paleozoic and Mesozoic rocks. (ii) To the west, as at Farmhamna, fossiliferous Carboniferous strata are seen vertically adjacent to Vestg6tabreen-Bullbreen Varanger strata. (iii) The schistose complex dips beneath glaciers, to the west of which rise Carboniferous mountains. This relationship is easiest to explain by postulating a further arcuate thrust occupying the ice-covered area rather than by an arcuate normal dip-slip fault. (iv) The Vestg6tabreen-Bullbreen thrust mass swings round from eastwards verging in Motalafjella to northwards verging in Bulltinden which is consistent with a dextral transpression. (v) In 1968 Harland showed Horsfield, on the south flank of the spur of Motalafjella north of Skipperbreen, a lens of fossiliferous limestone of Carboniferous facies in an apparent thrust surface. It is not impossible that it could have been Silurian. That possibility was not then in mind. A post-Bullbreen Group pre-Carboniferous tectonic episode might also have taken place.

Succession of the Complex. In view of the complexity of the metamorphic rocks, which all show evidence of shearing, any succession may not relate to an original stratal or thrust sequence. Nevertheless, Kanat & Morris mapped the following sequence, listed here from the (?) thrusted unconformity:

CENTRAL WESTERN SPITSBERGEN their orange weathering dolostone medium grey micaceous marble dark grey micaceous marble mafic schist serpentinite pelite schist greenstone psammite garnet glaucophanite eclogite

(VOD) VM2 VM1 VSH VSP VPE VGT VP3 VGG VEC

up to 20 m 50+ m 50+ m c. 200 m 15 m 10 m 50 m 4m 50+ m 40+ m

Ohta, Hirajima & Hiroi (1986) described two units separated by a west-dipping thrust. The lower unit (structurally is mainly of sericite chlorite phyllites with scattered lenses of dolostone, quartzite, metabasite and serpentinite. The upper unit is of garnet mica schists, schistose limestone and lenses of garnet glaucophanite and eclogite.

Mineralogy and chemistry of the complex.

The blue-schist facies has attracted much research. Horsfield (1972) described glaucophane schists (but did not find lawsonite, aragonite or pumpellyite) in the course of his chemical analysis and isotopic dating of them. Ohta (1979) reported both the bulk chemical composition and that of individual mineral species analysed by a number of workers. Typical mineral assemblages were:

glaucophane schists: garnet-glaucophane schist with muscovite and chlorite; garnet-muscovite-glaucophane schist; garnet-epidote-muscovite-glaucophane schist; eclogitic rocks: schistose glaucophane-garnet-omphacite (up to 90%) eclogite; epidote amphibolites: actinolite-epidote sericite-chlorite-plagioclasequartz schists; epidote calcite-chlorite-actinolite-plagioclase-greenstone; garnet-bearing epidote amphibolites: garnet-epidote-actinolite-chlorite meta-diabase; garnet-epidote-sericite-actinolite schist; garnet-actinoliteepidote-chlorite-sericite-plagioclase schist; garnet-chlorite-sericite-plagioclase-quartz-metagabbro; glaucophane-muscovite-quartz schists: variably with garnet or hematite. Ohta (1979) compared the above with other west-coast basic rocks. But in referring them to Late Riphean he was not aware of the evidence that the basites are intertillite and if so of Varanger age. He concluded for the origin of the Vestg6tabreen complex as follows. 1. Most epidote amphibolites were derived from intermediate differentiates of basaltic magma. 2. Some relatively acidic varieties are not later differentiates of basaltic magma, but mixtures of intermediate differentiates and argillo-siliceous sediments. 3. The muscovite-quartz schists with or without glaucophane were formed from impure argillaceous quartzite. 4. The glaucophane schists are mixtures of early differentiates of the basaltic magma and argillo-siliceous sediments. 5. Na enrichment is not prominent in the glaucophane schists and the original rocks were not typically spilitic. 6. The original volcanic rocks of these basic rocks are unknown, and they have large variation presumably by tectonic stirring. Kanat (1984) described jadeite from the upper member and estimated pressures between 9.9 + 0 . 5 k b as at 300~ and 12.8kb as at 450~ Horsfield's first estimate from the garnet-biotitehornblende assemblages suggested 300~ at peak metamorphism with a palaeogeothermal gradient of 30~ km -1. Ohta, Hirajima & Hiroi (1986) reported i.a. lawsonite and jadeite-quartz-albite assemblages.

9.5

Proterozoic strata of Oscar II Land

The overall stratigraphy of the area was first reconnoitred by C. B. Wilson in 1958 (Harland 1960) and with further work was synthesised by Harland, Horsfield, Manby & Morris (1979), and by Hjelle, Ohta & Winsnes (1979) and by Kanat & Morris (1988) and then by Harland, Hambrey & Waddams (1993). The rocks are described in three groups: Comfortlessbreen; St

Jonsfjorden and Kongsvegen.

9.5.1

165

Comfortlessbreen Group

The group is now defined by the Annabreen and Haaken formations. A meta-tillite was first suspected and the rocks so named (Harland 1960) since when a complex series of reinterpretations of the stratigraphy end with the scheme presented here (Harland, Hambrey & Waddams 1993). In that work, Aavatsmarkbreen was described in detail with four sections plotted from Sarsoyra and Kaffioyra. They regarded it as the highest formation in the Comfortlessbreen Group and possibly Late Vendian (Ediacara) age to correspond to the Scotia Group in Prins Karls Forland. However, from Ohta et al. (1995) the evidence suggests that the formation belongs to the Bullbreen Group where it is treated under Section 9.4.1.

Annabreen Formation (thickness variable, about 2 km). Wilson referred to Annabreen Quartzites and although the eponymous locality Anna Sofiebreen is south of St Jonsfjorden. The best sequence is seen around Aavartsmarkbreen. Cutbill & Challinor (1965) renamed them Irenebreen Quartzites as [?] Carboniferous whereas Hjelle, Ohta & Winsnes (1979) incorporated them in the Bullbreen Group. Harland, Hambrey & Waddams (1993) made it a constituent formation of the Comfortlessbreen Group. The formation comprises quartzites and shows gradational transitions above and below with thin phyllite interbeds above and dispersed dolostone and quartzite pebbles, up to 30 m at Dahltoppen, towards the base. Haaken Formation, 2-3 km (Harland, Hambrey & Waddams 1993). The name Haaken schists was used informally by C.B. Wilson (his horizon 7 in Harland 1960) and is best seen at Engelskbukta. Hjelle et al. 1979 referred to the same unit as tillitic conglomerate. The outcrop width of 6 km of steeply dipping strata was estimated by Waddams (1983) to have been duplicated by folding and thinning to about twice the original thickness. An eastern belt of the same formation is accessible from the head of St Jonsfjorden. The formation consists of stone-bearing orange to grey weathering psammitic schist - or schistose diamictite, interbedded with blue and grey weathering quartz-rich schist and laminated quartzite, the schistose foliation follows approximately the original bedding. The stones, comprising about 10% of the rocks, consist of dolostone, limestone, quartzite and both foliated and unfoliated granitoids up to lm long (the largest seen 2 • 1 • 0.7 m). Whereas the Annabreen facies is of proximal turbidite facies the Haakon facies is of distal turbidite facies, both with ice-rafted stones.

9.5.2

St Jonsfjorden Group

Defined by Harland et al. (1979) as comprising the four following formations, Harland, Hambrey & Waddams (1993) argued that the whole Group is Vendian (early Varanger). Hjelle et al. 1979 made them pre-Vendian, referring to them as Middle Hecla Hoek, and Ohta et al. (1995) implied a Mesoproterozoic age.

Alkhorn Formation 1+ km. The name is from 'Alkhornkalk' of Holtedahl (1913) conspicuous at Alkhornet on the southern cliffs of Oscar II Land where the lower part of the formation is exposed. Independently in north Oscar II Land, Harland (1960) recognized Holtedahl's Alkhornkalk, whereas Wilson used the name Dahlbreen limestone which Harland et al. (1979) regarded as the same unit and so adopted the earlier name. It was also referred to by Hjelle et al. 1979 as the Calc-argillo-volcanic Formation, metavolcanic and intrusive rocks having been recognized mainly in the upper part. A complex succession of facies (Harland, Hambrey & Waddams 1993) may be summarized as an alternating sequence of marble or grey limestone (often oolitic) and a variety of metabasites. Ohta (1984) referred to the igneous assemblage (the rich tholeites) as of oceanic type. Lovliebreen Formation, 1 km. The Formation is named for a glacier south of St Jonsfjorden (Harland et al. 1979). This unit corresponds to the dark quartzites of Holtedahl (1913), the massive quartzite bodies of Weiss (1953) and broadly equivalent to the Quartzite Shale Formation of Hjelle et al. (1979). A modified map (Ohta 1984) plots a broad belt from Loveliebreen to Isfjorden whereas north of St Jonsfjorden there is only a small outcrop. Two members have been distinguished (Harland et al. 1979).

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(2) Upper: massive dark quartzites with intercalated pelites the quartzites, are cut by thin white quartz veins - they are well- sorted fine-grained metasandstones. (1) Lower: foliated dark brown, green and purple volcanic rocks, with amygdaloidal basalts and pyroclastics. Some are reddened suggesting subaerial weathering. Unlike the Alkhorn Fm the igneous facies suggest sodaalkaline lava flows with some pillow structures. Geochemically they are of a non-oceanic type (Ohta 1984). Kanat & Morris (1988) made the Loveliebreen younger and than the Alkhorn units. Harland, Hambrey and Waddams (1993) disagreed believing i.a. that intrusive dolerites and the Loveliebreen volcanics had been confused. The latter may not have seen by Kanat & Morris.

Moefjellet Formation, 500-800m. C. B. Wilson named this massive, uni-form, unfoliated, cream-weathering bluish grey dolostone with a gritty or sandy texture and some cherty layers. Shallow water deposition with algae mats has been suggested. Daudmannsodden Formation (Ohta 1985) of highly sheared dolomitic marble could be a tectonised equivalent of the Moefjellet Formation (Harland, Hambrey & Waddams 1993). Trondheimfjella Formation (1.3 km). This schistose calc-diamictite was so named by Wilson as a conglomerate. His map was available to the Norsk Polarinstitutt who (Hjelle, Ohta & Winsnes 1979) remapped it as part of their Tillitic Conglomerate Formation and near the top of their sequence. Harland e t al. (1979) in the succession followed here, placed it at the bottom of their succession as did Wilson. Waddams (1983) found a tillite facies north of Engelskbukta and identified it with the earlier Varanger tillite (i.a. lacking granitoid stones). This was accepted by Harland, Hambrey & Waddams (1993) as evidence that the overlying formations of the St Jonsfjorden Group lie between the upper and lower tillite horizons and so must all be of Varanger age. Perhaps this realisation encouraged the solution to problem of correlation along the west coast, where, as in Oscar II Land, thick successions, with a basic igneous component, were all formed between or within the two Varanger glacial episodes and so restrict much of the west coast Proterozoic sequence to Vendian age. The meta-diamictites are distinguishable from those of the Haaken Formation by a matrix-rich carbonate rather than a phyllite and by the lack of exotic clasts such as granites and gneisses, the stone content being typically intrabasinal. These characters suggest an origin by ice rafting into a distal turbidite basin. A band of stromatolites near F a r m h a m n a indicates shallow marine carbonate shelf, or proximal environment. Harland e t al. (1979) proposed three members. (3) Marble flags (500 m). (2) Dark phyllitic semi-pelites and psammites with minor quartzites and calcareous beds (300 m). (1) Thin orange-weathering bands of calcareous in conglomerates a sequence of quartzites, psammites and massive dolostones (300 m). The upper contact is transitional and the lower contact faulted. There is no basal conglomerate with clasts matching the underlying formations.

9.5.3

Kongsvegen Group

In his survey of Broggerhalvoya Orvin (1934) set up 11 units of metamorphic rocks as follows, unit 1 at the top: 1-9 10 11

'Quartzite and mica schist series' (2520 m) Steenfjellet Dolomite (270 m) Bogegg Mica Schist (1500 m). The matter proved complex as follows.

Orvin (1934) identified a further unit, 'dolomites and limestones', beneath with his units 1-11 (see below) and Challinor (1967) referred to this as the Bjorvikfjellet Formation. Harland et al. (1979) identified this with the overlying Trondheimfjella Formation (confirmed by Harland, Hambrey & Waddams 1993).

Correlating northwards across Kongsfjorden, Orvin made the Blomstrandhalvoya marble (Genaralfjella Formation) his topmost unit of the Hecla Hock succession above unit 1; the schists of Signehamna Formation (equivalent to his units 1-9), and the Nissenfjella Formation with its feldspathic rocks (migmatites) as the granite of the pre-Hecla Hock basement. Little was then known of other pre-Devonian successions and proceeding with this sequence as seen from the north his scheme was coherent. Wilson's reconnaissance of the rocks of Oscar II Land south of Broggerhalvoya in 1958 led to his reversing the succession with his Trondheimfjella rocks above the Bogegg schists, as reported and followed by Harland (1960). However, when revising the Hecla Hock succession in Ny Friesland, Harland et al. (1966) referred to the Kongsvegen Gp comprising Orvin's three formations and (knowing Challinor's t967 conclusions) followed Orvin's order of succession. Challinor (1967), while not accepting Orvin's correlation north of Kongsfjorden, named Orvin's units 1-9 the Nielsenfjellet Fm (at the top) and Orvin's 'dolomites and limestones of Forlandsundet' as the Bjorvigfjellet Fm at the bottom of the Kongsvegen Gp (Harland et al. 1966) underlying the 'Bogegga Fm' so again following Orvin's order of superposition. However after a reconnaissance survey of the whole of Oscar II Land Harland et al. (1979) concluded that Wilson had been correct in that the Kongsvegen Gp was the oldest in that area (and probably younger than the rocks further north). Nevertheless, it was assumed that the metamorphic grade of the Kongsvegen Gp made it significantly older than that of St Jonsfjorden G p - that, indeed, it was a potential basement to the St Jonsfjorden Gp. They retained Orvin's sequence, adding detail of the Bogegg Fm. Further study of Oscar II Land (Harland, Hambrey & Waddams 1993) led to the view that the Mfillerneset Fm (south of St Johnsfjorden) which was correlated with, and included in, the Kongsvegen Gp might have been conformable (at least concordant) with the Trondheimfjella Fro. In 1992 CSE concluded that, as seen north of Engelskbukta, the Boggegg, Trondheimfjella, and the Moefjellet fms lay in a normal sedimentary sequence with interbedding and transitional facies at the boundaries. No evidence for any major discontinuity (unconformity, thrust or both) was evident locally. Inadavertently they tabulated Orvin's order of the Kongsvegen Gp which they had not investigated. The conclusion here is quite clear in spite of the above confusion. Wilson was correct: the Trondheimfjella Formation at the base of the St Jonsfjorden Group rests concordantly on the Bogegga Formation at the top of the Kongsvegen Gp. In the light of the above complex sequence of opinions the conclusion is summarised below. The apparent differences in metamorphic grade are probably accounted for partly by composition of the protolith and partly by depth in the succession.

Kongsvegen Group North of St Jonsfjorden Bogegg Formation, 1500m, is a varied sequence, dominantly pelitic Member (3), 500 m. Half the bulk is of pelites and semi-pelites of biotite and garnet schists containing quartzo-feldspathic bands and lenses. These are intercalated with orange-weathering marbles and psammites. The other half is of coarse grained marbles Member (2) 500m. Dark feldspathic and garnetiferous semipelite with quartz feldspathic bands and segregations. Member (1) 500m. Gneissic porphyroblastic (augen) feldspathites and semipelites and schistose garnetiferous pelites dominate with bands of dolostone and impersistent concordant amphibolites. Steenfjellet Formation, 270 m a convenient prominent marker formation of grey to cream coloured dolomitic marbles separates the formations above and below. Nielsenfjellet Formation (2+km) (Challinor 1967, Orvin's Quartz Mica Schist Series) of monotonous dark phyllitic semi-pelites interspersed with paler, dolomitic quartzite bands. Orvin's description of these rocks (unit 1-9) applies to the cliffs north of Austre Broggerbreen. The mountains further east - towards Nielsenfjellet yield a variety of schists and gneisses with an igneous component and whose relationships have yet to be determined. South of St Jonsfjorden Miillerneset Formation. Occupying the west coast between St Johnsfjorden (Mfillerneset) and Eidembukta, the Formation consists of phyllitic and schistose pelites interbedded with semipelites and white quartzites (Harland et al. 1979; Hjelle, Ohta & Winsnes 1979; Ague & Morris 1985; Kanat & Morris 1988).

CENTRAL WESTERN SPITSBERGEN North of Eidembukta the strata appear concordant and transitional beneath the Trondheimfjella Formation. The metamorphic contrast which has led to the view of a much older unit may stem from the tectonic juxtaposition of M~illerneset and Comfortlessbreen rocks where the whole intervening St Johnsfjorden Group (>4 km) is not seen.

Oscar II Land an Ordovician to Silurian age. That no fossils have yet been recorded may be the consequence of such a mobile environment. How much and what parts of Early Paleozoic time is represented can only be guessed.

9.6.2 9.6

Pre-Carboniferous rocks of Prins Karls Forland

A p a r t from Q u a t e r n a r y cover no D e v o n i a n or y o u n g e r rocks have been identified on Prins Karls F o r l a n d and an apparently uninterr u p t e d sequence o f strata m a y contain a u n i q u e passage for Svalbard from V e n d i a n t h r o u g h early Paleozoic strata; but with little palaeontological evidence to confirm it (see Fig. 9.8). The island is easily accessible and m u s t have been visited m a n y times. H o w e v e r , the evident lack o f macrofossils m a y have t u r n e d geologists elsewhere until the systematic study by Tyrrell (1924) and later by A t k i n s o n (1956, 1960 and 1962). E x p l o r a t i o n h a d tended to be a British interest since t o p o g r a p h i c surveys u n d e r Bruce's leadership of the Prince of M o n a c o expeditions in 1907, 1908 and 1910, and the attentions of the Scottish Spitsbergen Syndicate (Tyrrell 1924). The rocks were described by M a n b y & Morris (in H a r l a n d et al. 1979) a n d by Hjelle, O h t a & Winsnes (1979). W h e r e a s the second of these gave valuable description of the rocks only the first p a p e r a r g u e d a stratigraphic sequence. H a r l a n d , H a m b r e y & W a d d a m s (1993) in their synthesis followed that sequence. The detailed occurrence and origin of the names is given in the 1979 paper, w h e r e possible names were taken from the previous w o r k o f Tyrrell a n d Atkinson.

9.6.1

Grampian Group (Early Paleozoic)

This g r o u p is typically siliciclastic and flyschoid, it is defined by the following five formations.

Geddesflya Formation >1800m. This upper-most unit occurs in the northern part of the island. It is mainly quartzitic with dolostone banded siltstones, breccias, thin siltstones and slates. Lower down are slate-pebble breccias with banded siltstones. Lower still are thinly bedded quartzites and banded siltstones. Fugelhuk Formation 400-1000 m. Massive bedded quartzites occur in the cliffs at the north of the island. Beds, commonly one metre thick, are interbedded with banded siltstones. They thicken northwards to 1000 m. Barents Formation, 500m. This formation is dominated by siltstones which locally become black to dark grey slates. Below this is a sequence of folded banded siltstones and below again flaggy calcareous sandstones and then green pelitic quartzites with black limestone and pebbly quartzite. The remarkable Sutorfjella Conglomerate is treated by us (as by Atkinson) as a member within this formation although others have regarded it as a younger independent unit such as Devonian (Hoel 1914; Craig 1916) or Tertiary (Tyrrell 1924). They were first reported by Hoel. Krasil'shchikov favoured a Tertiary age. But CSE observed near the shore to the south evidence of interbedding with the Barents slates. The conglomerate contains clasts of underlying formations- mainly brown weathering, pale grey quartzite. Some horizons are rich in green cleaved siltstone, similar to that of the matrix. Another clast type is black mudstone with quartz~lolomite veining. These rock types are sufficiently distinctive to give confidence in this order of superposition. The quartzite boulders show red oxidized skins suggestive of subaerial weathering. The whole assemblage could have formed on a fault scarp. The cleavage of the matrix and of many clasts parallels that of the Barents Formation as a whole. Conqueror Formation, 500-850 m. Transitional with the Barents Formation at the top of the Conqueror Formation is a distinctive sequence of quartzites and slates. Below this are dark grey slates alternating with quartzite. Pebbly calcareous beds then overlie thick slate with more quartzite bands. The formation thickens northwards. Utnes Formation, 80m. This formation is transitional between the Conqueror and the underlying Roysha Formation. The distal turbidite facies, especially of the Barents Formation but also elsewhere in the Grampian Group suggest by litho-correlation with the Hohnsletfjella beds of

167

Scotia Group (Late Vendian-Ediacara)

Tyrrell (1924) and M a j o r , H a r l a n d & Strand (1956) referred to this as the M o u n t Scotia series and A t k i n s o n as the Scotia G r o u p . It is defined by the following three formations.

Roysha Formation c. 400 m. The Roysha Formation is of very soft black carbonaceous slate interbedded with dolomite siltstones. Manby (1986) referred to this unit as the Omondryggen formation. Kaggan Formation c. 300 m. The Kaggan Formation consists of tight isoclinally folded slate phyllonites. The distinctive green and purple striped slates suggest a minor volcanic component metamorphosed with chloritoid. Baklia Formation. Exposed near lake Baklia in a passage downwards from black slates with quartzites to a black carbonaceous slate sequence containing grey-orange dolomitic limestones with inraformational breccias. The lower part of the formation consists of grey, frequently cherty, dolomitic siltstones with black slates. Below this are quartzites, frequently conglomeratic, with green and black slaty laminae and then dolomitic cherty limestones. When the sequence, described here from Prins Karls Forland, was published no fossils had been found in situ on the island. However, the cherts in the Baklia Formation, referred to as the Black Carbonate Pelite (BCP), have yielded microfossils (Knoll & Ohta 1988). The dolostone is oolitic in places. The following taxa were described and figured. Eomycetopsis robusta Schopf, emend. Knoll & Golubic (1979); Eomycetopsis sp.; Siphonophycus inornatum Zhang; Siphonophycus sp.; Myxococcoides sp.; Obruchevella Reitlinger (1959); ?Obruchevella sp. Poorly preserved acritarchs include leiosphaerid-like vesicles and rare spheres with vesicles and with an outward layer of hollow processes, typical of Late Riphean and Vendian strata in Russia; of the Doushantuo Formation of central China and of the Pertatateka Formation of central Australia, these occurrences being of latest Proterozoic age. Knoll & Ohta (1988) concluded that 'the most likely age for the BCP beds is Late V e n d i a n - i.e. post-tilloid but Precambrian in age' and they stressed the uncertainty of this age because Hjelle, Ohta & Winsnes (1979) had placed this unit below the tillite horizon. From their localities on the map Harland, Hambrey & Waddams (1993) matched the lithology with the Baklia Formation. It seems that the BCP of Knoll & Ohta is the Black Shale Formation of Hjelle et al. (1979). It is likely that these units belong to the Scotia Group. Whatever the detailed stratigraphy, Prins Karls Forland thus contains the first Ediacara biota to be recorded in Svalbard. This age fits well the sequence of Harland et al. (1979).

9.6.3

Peachflya Group

These rocks were first n a m e d by Tyrrell the Ferrier Peak Series a n d m a y have been referred to by A t k i n s o n as the K e r r G r o u p . It was defined by four f o r m a t i o n s w h i c h were defined by H a r l a n d et al. (1979) and followed by H a r l a n d , H a m b r e y & W a d d a m s (1993).

Knivodden Formation, 400 m. Incompetent chloritoid phyllites pale grey, dark grey and pale green. Hornnes Formation, 350m. Siliceous-phyllite, sandstone quartzite, limestone alteration. Alasdairhornet Formation, 190m. Volcanic suite- banded and welded tufts with some basic lava flows. Thin carbonate interbeds occur near top and base, marked by reworked volcanogenic and siliciclastic material. Fisherlaguna Formation, 350 m. Incompetent blue phyllites.

9.6.4

Geikie Group

This g r o u p ( H a r l a n d et al. 1979 following Atkinsons, 1960, name) unlike the overlying groups has thrust r a t h e r t h a n sedimentary contacts at the b o t t o m .

Rossbnkta Formation (>300 m) of dark siliceous phyllite which becomes increasingly calcareous towards the base.

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Gorden Formation (>470 m). Calcareous phyllite with 3 to 4m massive dolostone-limestone laminated horizons with intraformational breccias, carbon-rich beds, and pisolitic limestones.

9.6.5

Ferrier Group

The Ferrier Group comprises four formations. All are typically schistose diamictites of biotite grade. They have been interpreted (Harland et al. 1979) as distal flyschoid marine tillites. They dominate the mountains of central Prins Karls Forland south of Selvgtgen.

Neukpiggen Formation (270 m). Consists of calcareous and chloritic schist with discontinuous psammite, marble and conglomerate beds. Dispersed dolostone and quartzite stones occur throughout the schist and phyllite. Granite stones 10 mm to 0.4 m long and marble stones 50-100 mm long were recorded. Small folded psammite blocks suggest slumping, pene-contemporaneous erosion and resedimentation at some horizons. Peterbukta Formation (160m). Comprises pink-, grey-weathering, psammitic schist, grey calcareous schist and dark pelitic schist with discontinuous beds of clear crystalline psammite and dolostone orthoconglomerate, and intraformational conglomerates. Outsize stones occur throughout. Hardiefjenet Formation (120-500m). Upper division of pale, calcareous siliceous schist and lower division of dark green schist. Similar to Neukpiggen Formation but darker in colour and higher metamorphic grade. Isachsen Formation (> 150 m). Consists of dark green quartz chlorite schist with brown interlayers and numerous pressure solution quartz segregations. Thin layers of diamictite occur, but mostly thin-bedded or laminated and somewhat sorted. Beds of tuff 1-2 m thick are disposed through the formation. The base is not exposed. Alfred Larsentoppen Unit. In addition to the main outcrop there is an isolated klippe on Alfred Larsentoppen - the only such diamictite north of Selvgtgenand Scotiadalen. The upper 20 m are of orange weathering, coarse dolomitic psammite with dispersed stones of grey dolostone - more numerous and larger than in the four formations described above. The lower unit is rich in granitoid boulders. Because both of their granitoid content and their stratigraphic position we correlate all these tilloids with the Comfortlessbreen Group; that is the Later Varanger glacial episode (Mortensnes).

9.6.6

Pinkie Formation

The Pinkie Formation occurs as a thrust slice between overlying Conqueror quartzites and underlying Geddesflya siltstones and quartzites. It consists of quartz biotite schist, feldspathic magnetite biotite schist, felsite, and a calcareous brecciated slate rich in biotite. The formation is of higher metamorphic grade than any other rocks recorded on the island and, as it does not match any of them closely in composition, it has been presumed to be a slice of an older complex. Considering the mainland succession, the strata preceding the Comfortlessbreen Group diamictites are rich in basic igneous material. This suggests that the Pinkie Formation was derived by (?Ordovician) metamorphism from the Lovliebreen Formation (Harland, Hambrey Waddams 1993; Ohta et al. 1995) in the St Jonsfjorden Group. So in this work it would be part of the Early Varanger sequence

9.7

Structure of Oscar II L a n d

Triassic through Carboniferous strata crop out extensively in northern and eastern Oscar II Land and their deformation displays the structure of the Paleogene West Spitsbergen Orogen. In Western Oscar II Land the pre-Carboniferous basement was affected by at least one earlier tectonic episode as well as by the Paleogene orogeny. Oscar II Land is a prime region for the study of structures related to the West Spitsbergen Orogeny (e.g. Orvin 1934; Challinor 1967; Maher 1988; Manby 1988; Winsnes & Ohta 1988; Bergh & Andresen 1990; Bergh et al. BSG, 1993; Andresen,

Bergh & Haremo 1994; Bergh, Braathen & Andresen 1997). Localized structural studies have been carried out in three areas: Broggerhalvoya in the northwest, eastern St Jonsfjorden in the centre, and the Lappdalen/Mediumfjellet area in the southeast. Most of the interior has been mapped from aerial photographs, but many western parts have yet to be mapped in detail. Oscar II Land is divided here into four areas: northwest, southwest, centreeast and centre-west (9.7.1-9.7.4).

9.7.1

Northwest Oscar II Land

Broggerhalvoya and Kongsfjorden. Broggerhalvoya is located in the northwest part of Oscar II Land and represents a significant change in the vergence of structures in this orogen, from an essentially easterly to a northerly vergence. This is particularly evident along the southern margin of Kongsfjorden, where structures tend to strike parallel to the coast (Challinor 1967). The area between Broggerhalvoya and Engelskbukta in the northwest part of Svalbard illustrates the involvement of basement (pre-Devonian) in the Paleogene fold-and-thrust belt. The large-scale structure of the area consists of a series of northto northeast-vergent thrust nappes dominated by post-Devonian strata in the northwest part of Broggerhalvoya and by preDevonian strata in the southeast part of the peninsula, Engelskbukta and northern Oscar II Land. A major N-S-trending fault zone in the vicinity of Broggerbreen (referred to as the Scheteligfjellet Fault Zone by Challinor (1967) separates the nappes in the northwest from those to the southeast and south, but does not continue into the structurally higher nappes of the southern part of the area. Manby (1988) interpreted this structure as a transfer zone along which the more northerly displacement of the southeastern nappes has been accommodated by sinistral shear. In northwest Broggerhalvoya, the younger rocks are stacked into three major nappes. The Broggertinden Formation is deformed into broad open folds along the Kongsfjorden coastline indicating that the floor thrust to the lowest exposed thrust nappe is ramping up at this point (Manby 1988). Structures within the Wordiekammen Fm are well exposed in Scheteligfjellet, with the upper duplex considerably more deformed than the lower. The whole of the higher nappe is folded into an overturned, north-vergent, anticline-syncline pair, where a late thrust repeats part of the lower limb of the syncline that carries Gipshuken over Kapp Starostin rocks. The highest of the three nappes in the northwest comprises a pre-Devonian to Early Permian sequence that is floored by a low-angle south- to southwest-dipping thrust, where the high cut-off angle between this thrust and the steeply dipping, overturned hangingwall rocks indicates that overfolding preceded thrusting. According to Manby (1988) a minimum of 12 km of shortening is necessary to account for the deformation in the uppermost nappe, and at least 18 km when taking the whole nappe sequence in northwest Broggerhalvoya into consideration. To the southeast of the Broggerbreen Fault, the lowest nappe contains a sequence of Paleogene to Broggertinden (Bashkirian age) strata that are folded into a broad northwest-plunging syncline which is itself overthrust by the recumbent Zeppelinfjellet syncline. This thrust sheet is characterized by small-scale imbricates, duplex structures and folded thrusts (Challinor, 1967). The pre-Devonian rocks in the overthrust sheet consist of metamorphic rocks of the Kongsvegen Group (Harland et al., 1979), the whole sequence being characterized by a well-developed anisotropy with shear fabrics and mylonitic zones refolded on various scales by north to northeast vergent crenulation-type folds, consistent with Paleogene deformation of the lower nappe. Moefjellet marbles have been strongly deformed into an imbricated sequence above the Trondheimfjelletnappe and are unconformably overlain by a synclinally folded and cleaved sequence possibly of Billefjorden Group at the head of Nordenfjeldskebreen. Waddams (1983) noted that these rocks were subsequently overthrust by the Haaken tillite succession. To the southeast of the col, at the head of Nordenfjeldskebreen, the Haaken and Moefjellet rocks are defined by thrusts in which Alkhorn marbles also became incorporated (Harland et al., 1979). The presence of post-Devonian rocks in the higher nappes and identical vergence directions in both sequences indicate that the deformation of the pre-Devonian rocks is related to the Paleogene West Spitsbergen Orogeny.

CENTRAL WESTERN SPITSBERGEN

Kongsvegen to St Jonsfjorden.

The area between Comfortlessbreen and Sarsoyra is defined by a shallow southwest sheet dip of the Haaken tillites. Along the southern shore of Engleskbukta the Caledonian S1 foliation is refolded by open box-like folds overturned to the northeast, with a characteristic pressure-solution cleavage developed. Interpreting the structure of the pre-Carboniferous basement depends on some knowledge of its stratigraphy. Harland, Hambrey & Waddams (1993, p. 56) outlined a scheme for Oscar II Land with a tentative thrust extending from the snout of Comfortlessbreen southeast through Lovenskioldfonna to make stratigraphic sense; but there are many more faults. Detailed mapping is awaited. On this interpretation the thrust would be consistent with a Paleogene dextral transpressive motion. To the west of Kapp Graarud, Tertiary conglomerates lie above the pre-Devonian strata, with both sequences cut by steep westdipping to vertical faults, striking broadly N-S. The conglomerates show small-scale sinistral and dextral displacements of pebbles that can be related to anastomosing fractures parallel to the faults. Ohta et al. (1995) described the structure of Sarsoyra and Kaffioyra as a complex strike-slip fault system with variable orientations of each domain as evidence of dextral transpression in a deep shear zone.

9.7.2

169

conglomeratic horizons containing clasts showing evidence for a pre-depositional deformation fabric. The immature nature of the Bulltinden Conglomerate suggests rapid deposition from a local source. The presence of the conglomerate indicates that there was a significant uplift phase. The timing of deposition is derived from the late Llandovery to Wenlock ages of the, the Motalafjella Limestone, lowest formation of the Bullbreen Group (Scrutton et al. 1976). Svalbardian (Late Devonian) movements, sinistral transpression according to Harland (1985), was later than deposition of the Bullbreen Group. Kanat (pers. comm.) suggested that the Bullbreen Group should have suffered some degree of deformation. This episode may have been concentrated in the shear zones. Tight small scale sinistral isoclinal folds are conspicuous in the westernmost outcrops of Daudmannsodden in southwest Oscar II Land (Harland, Hambrey & Waddams 1993). This would imply, therefore, that younger sediments deposited on the Bullbreen Group should be in unconformable contact, although this type of contact has not been identified. Weiss (1953) identified an unconformity at the base of the Carboniferous rocks where they were in contact with lithologies associated with the metamorphic complex. However, a sedimentary contact between the Bullbreen Group, of inferred Silurian age, and younger rocks has yet to be recognized. It is unfortunate that the outcrop of Bullbreen strata is limited to so few exposures.

Southwest Oscar II Land

Weiss (1953) identified two deformation phases in the preDevonian basement rocks to the south of St Jonsfjorden. Horsfield (1970) similarly defined two major phases, corresponding to Paleozoic and Paleogene events. More recently, K a n a t & Morris (1988) suggested a more complex tectonic history.

The Eidembreen phase (D1 of Kanat & Morris 1988) of early to mid-Ordovician age. Throughout southwest Oscar II Land, the metamorphic complex, particularly that of the Vestg6tabreen Formation, exhibits evidence of an intense deformational phase; this episode also produced a penetrative cleavage (S1) and related metamorphism. Structures such as folds and boudinage, which have a consistent relationship to S 1, are attributed to D 1. The style and intensity of folding, as well as the development of the S 1 fabric, is inhomogeneous and can be attributed to the largely anisotropic behaviour of the basement rocks. The following is based partly on Kanat (pers. comm.). The penetrative $1 cleavage is variably developed in the preCarboniferous Vestg6tabreen Fm as a mineralogical banding, particularly in the more massive lithotectonic units such as the brecciated dolostone, psammite, eclogite and serpentinite divisions. The S1 fabric has a variable orientation throughout the area to the south of St Jonsfjorden, although in general many of the platy metamorphic minerals are parallel to S1. On the mesoscopic scale the mineralogical banding in the psammite division is correlated with the S1 fabric of the associated divisions of the Vestg6tabreen Fm. SO (bedding) if preserved is expressed as helical inclusion trails in garnet porphyroblasts; in general SO is indistinguishable from S1 within the metamorphic complex, i.e. they are parallel. Inclusion trails within garnets, flattened chloritoid rosettes and the alignment of amphiboles and mica, suggest that metamorphism was pre- to syn-D 1. On the megascopic scale, D1 is associated with metamorphism, uplift of the Vestg6tabreen Fm, and thrusting and folding of the metamorphic complex. The general positions of the main lithological units of the metamorphic complex (i.e. the Comfortlessbreen Gp to the west and the St Jonsfjorden Gp in the eastern part of the St Jonsfjorden area), and the development of the (now) tight asymmetric folds within the metamorphic complex were formed at this time. The vergence of minor folds within the Vestg6tabreen Fm shows no significant correlation with that of the major fold structures (e.g. at Motalafjella) and they are therefore of different ages. Similar structural fabrics to those recognized in the Vestg6tabreen Fm are also found in the Comfortlessbreen and St Jonsfjorden groups. The Bullbreen Group was deposited later (Caradoc to Wenlock). This group has a distinct molasse-type character with major

Tectogenesis of the Eocene West Spitsbergen Orogeny. This second main deformational phase (Spitsbergian) accounts for the present structural pattern in Oscar II Land, with most of the large-scale structures, folds and thrusts so generated (D2 of some authors). This phase may have produced a well-defined cleavage ($2) in the finergrained horizons (fine sands and slates) of the Bullbreen Group. The coarser lithologies of this group (sandstones and conglomerates) are strongly cleaved in some areas, but not in others, although cleavage is generally evident to some extent. Sedimentary structures (e.g. crossbedding, graded bedding, sole markings, flame structures and ball and pillow structures), vergence directions and bedding-cleavage relationships indicate large-scale stratigraphic inversion, particularly along the Skipperbreen-Vestg6tabreen ridge and Motalafjella. F2 folds show gently to moderately dipping axial planes and fairly tight fold geometries, with wavelengths of 0.5-1 kin. Bedding and cleavage are poorly defined in the Motalafjella Limestone, and the orange-weathering dolostone unit lacks any internal structure. The Bullbreen Group was not affected by the mid-Ordovician orogeny (D1). Weiss (1953), in contrast, did not distinguish the Bullbreen Group from the metamorphic complex and therefore suggested that the structures in southwest Oscar II Land were related to a mid-Paleozoic orogeny. Evidence for a mid-Paleogene age for the basement structures attributed to the D2 phase comes from the following observations. (a) Fold wavelengths of deformed Carboniferous rocks at Broggerhalvoya are similar to those in the Bullbreen Group. (b) The orange-weathering dolostone unit may represent a mineralized thrust zone, typical of Paleogene thrusting (Harland et al. 1979). (c) The east-verging emplacement directions are consistent with the regional plate tectonic regime in the North Atlantic and Arctic regions during early Tertiary time (Harland 1965, 1966; Wilson 1965; Horsfield & Maton 1970; Pitman & Talwani 1972; Talwani & Eldholm 1977; Eldholm et aL 1984). (d) Part of the Bullbreen Group is of mid-Silurian age (i.e.) Post-D1. (e) The Bulltinden Conglomerate contains clasts with a pre-depositional deformation fabric. (i.e) post-D1. (f) The Bullbreen Group shows one less deformational fabric than is evident in the metamorphic complex (Morris, 1988) (i.e) Post-D1. (g) Based on fold geometry, dip direction of fault zones and truncations of lithological units of the Bullbreen Group, the emplacement direction of thrust and fold nappes was inferred by Kanat (1985) to be towards the NNE; this is supported by stretching lineation data within the Bullbreen Group (Ratliff, Morris & Dodt 1988). The orange weathering dolostone unit is inferred to have developed along thrust zones during D2 time and forms the

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CHAPTER 9

discordant zone between the Vestg6tabreen Complex and the base of the Bullbreen Group (Ohta et al. 1983; Morris 1988; Kanat & Morris 1988). The rock is commonly brecciated and the interstices are filled with a light grey limestone derived from the Motalafjella Formation. Quartz grains show evidence for strong deformation (deformation bands, deformation lamellae, undulose extinction and a shape fabric). Overall the chemistry and structural and metamorphic styles indicate a close relationship to the Vestg6tabreen Complex. This unit is best developed in the overturned limbs of major folds where the Bullbreen Group is separated from the Vestg6tabreen Fm. It is well exposed at southern Bulltinden, but also occurs at southern Holmesletfjella and Motalafjella. In addition, Ratliff et al. (1988) noted the presence of a heterogeneous mylonitic fabric that indicates a detachment zone for northeasterly directed folding and thrusting of the Bullbreen Group over other basement units (Morris 1988). To the south of St Jonsfjorden the Bullbreen Group and underlying dolostone are folded into a recumbent synformal syncline below the overthrust Vestg6tabreen Complex (Ratcliff, Morris & Dodt 1988). Ratliff et al. (1988) suggested that the Bullbreen Group was deposited within a fault-bounded linear extensional basin related to uplift of the Vestg6tabreen Complex as part of a convergent orogenic wedge. Continued contraction forced both the Bullbreen and Vestg6tabreen units over the underlying pre-Devonian shelf and basin sediments. They argued (p. 341) that the Bullbreen deformation was pre-Carboniferous on the, possibly doubtful, evidence that the Carboniferous rocks (sandstones and conglomerates) to the west of the Bullbreen outcrop do not share the Bullbreen penetrative tectonic fabrics. The structure is conspicuously over-thrust to the N N E (with the Vestg6tabreen Complex), with elongation of pebbles in the conglomerate parallel to the fold axes (WNW-ESE) direction with a shear displacement (transpression) of 4 km. The structures could certainly be D2 on the above system, only the age remains uncertain. If the timing of Ratcliff et al. is correct, a major deformation similar to that of the West Spitsbergen Orogeny occurred after the Eidembreen event (taken by some as D1) and before the Carboniferous Cretaceous succession deformed in the Paleogene West Spitsbergen Orogeny. This could be a Devonian event, but dextral rather than sinistral, and for which no other such intense tectonism is known in the west. Alternatively the structure, which conforms in most respects with those of the West Spitsbergen Orogen (thrust and fold belt) would be Eocene as favoured here. In this case the dextral transpression would match the model of a Paleogene transpressive orogen. Indeed, on this basis the dextral transpressive structure described in detail by Morris (1988) would be Paleogene and not Paleozoic. Moreover two phases are distinguished: (i) a N S compression with concomitant dextral strike-slip and (ii) easterly directed thrusting. A late stage event within the West Spitsbergen Orogeny and associated with the development of N-S normal faults, and also with the development of broadly E-W-trending strike-slip faults (Waddams, 1983) has been distinguished as a later phase within D2. This phase is not easily distinguished from the more evident D2 phase (Manby 1978). Though Kanat (pers. comm.) described a later D4 event, there is only clear evidence for the three principal events discussed here but their age attribution is not altogether reliable. There is a further consideration. At F a r m h a m n a (SW of the snout of Idembreen) the strata are vertical with a NNW-SSE-strike and are clearly tectonized in some degree. However limestones with Carboniferous corals to the west are concordant with Early Varanger tillites to the east over a short distance as seen in cliff sections. This suggests an absence of any regional Vendian through Devonian (Caledonian) orogeny. The most recent available study (Maher et al. 1997) focused on the strip of mainly Carboniferous rocks, within pre-Carboniferous basement, extending parallel to the Spitsbergen Orogen from St Jonsfjorden to Isfjorden, along the eastern margin of the Forlandsundet Graben (their Svartfjella, Eidembukta, Dandmannsodden lineament). It is faulted throughout and clearly belongs to the Spitsbergian tectogenesis. They interpreted a sequence of phases:

1 E N E - W S W contraction; 2 orogen-parallel sinistral motion; 3 dextral orogen-parallel motion. Their study related the three phases to those somewhat different interpretations of graben history by Lepvrier (1990), Gabrielsen, Grunnaleite & Ottesen (1992) and Teyssier, Kleinspehn & Pershing (1995) and of the origin in Nordenski61d Land to the south by Braathen, Bergh & Maher (1995).

9.7.3

Central and eastern Oscar II Land

Structural observations in the interior of Oscar II Land are still mainly based on reconnaissance mapping and on the interpretation of aerial photographs (Challinor 1964; Harland & Horsfield 1974; Maher 1988a, b), although new data on eastern parts have been presented (Bergh et al. 1988a, b; Bergh & Andresen 1990; Bergh et al. 1993; Wennberg et al. 1992, 1994) and demonstrate the typically thin-skinned style of deformation. Maher (1988a, b) compiled a regional structure map of central and eastern parts, and identified three zones of distinctive structural style or geometry as follows. (i) A zone characterized in the north by thrusts with a complex geometry emplacing pre-Devonian rocks into and over the lower cover strata (Broggerhalvoya to St Jonsfjorden). In the south this zone is characterised by a series of stacked monoclinal to overturned folds of Kapp Starostin Formation strata, forming a 'staircase' geometry. (ii) A central zone characterized by folds within upper Kapp Starostin Formation and Triassic strata without obvious major thrusts (displacement greater than 1 km). (iii) A zone with at least two major thrusts that have emplaced Kapp Starostin Formation strata over Triassic strata. Fold geometries may be correlated with fault-bend folds, with angular hinges and flat tops (Suppe, 1985); smaller thrusts are also evident. The apparently regular and consistent orientation of many of the fold structures within the interior parts of Oscar II Land are a direct reflection of underlying fault geometries. The nature of the underlying structure is inferred as ramping in the pre-Devonian rocks, propagating, and flattening out in the weak gypsum horizons of the Gipshuken Formation; all slip would therefore be transferred along this horizon farther east (Harland, Mann & Townsend 1988; Maher 1988b). The central zone of folding displays open to tight folds in Kapp Starostin Formation and Triassic strata, with varying styles from conjugate to more rounded forms. Considering the mechanical competence of Kapp Starostin Formation strata it is unusual to find such tight fold geometries, e.g. to the south and west of Isfjorden (Maher & Welbon 1992). According to Maher (1988b) the folds interpreted from aerial photographs have neutral vergence, with axial planes essentially vertical; numerous small thrusts are likely, but large thrusts (displacements greater than 1 kin) are absent in most areas. The Kapp Starostin Formation upper boundary is identified repeatedly at the surface suggesting a sub-horizontal, envelopment surface for the folds, the implication being an underlying subhorizontal detachment. The gypsum horizons within the Gipshuken Formation form an obvious candidate for the underlying detachment (Harland & Horsfield 1974; Harland, Mann & Townsend 1988), and thus the gypsum horizons promote a zone of thin-skinned deformation. The folds that form above this 9-10 km wide detachment may represent buckle folds (Maher 1988b). Such a simple model, assuming concentric fold geometries, necessarily implies space problems at depth. On the basis of idealised fold geometries, Maher suggested that a perfectly concentric fold geometry provides an upper limit for the shortening estimate, for which estimates lie in the range 14-25% (of original length) with an average linear shortening of 2.2 km (about 20%) across the width of the central zone. The inferred depth to detachment is calculated to be in the range 364-694m and is consistent with a basal detachment within the lower parts of the Kapp Starostin Formation, or more likely within the underlying Gipshuken Formation (Challinor 1967; Maher 1988a, b).

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The Lappdalen-Mediumfjellet segment. The Lappdalen-Mediumfjellet thrust front in east Oscar II Land presents a structural profile through the stack of thrust sheets allowing an interpretation of the geometric relationship between the folding and thrusting; a detailed analysis was given by Bergh & Andresen (1990). Figure 9.6, summarized from that paper, shows the essentials of the structure. They described their traverse under the following heads from east to west.

(a) The Mediumfjellet-Lappdalen thrust front with west dipping stacked and imbricated thrusts with repetition of Sassendalen, Kapp Starostin and Gipshuken units. Incompetent Triassic strata display upright folds but the competent Permian strata form large amplitude chevron and box folds. Decollement zones select the incompetent Gipshuken and Botneheia Formations. (b) The Lappdalen transition zone about 2 km wide separates (a) and (c). (c) The Lappdalen fold and thrust zones. Four distinct thrust or fold structures were described (Bergh & Anderson). They are interpreted as the leading edge in an eastward propagating thrust system, based in a sole thrust within the Gipshuken Formation with advancing piggy-back thrusting. (d) The Mediumfjellet fold and thrust zones also exhibit four thrusts, with box-like disharmonic folds based on the Gipshuken evaporite zone, generally dipping west. Analysis of these profiles extending 10km E-W by balanced sections gave a minimum shortening of 4 km. Blind thrusts, hidden detachments or out-of-sequence thrusts would increase this estimate.

The T r y g g h a m n a - L a p p d a l e n segment. Structural mapping of Paleozoic and Mesozoic rocks in Oscar II Land within the West Spitsbergen Orogen, reveal a system of major asymmetric to overturned, east-vergent folds with NNW-SSE-trending axes, a c o m m o n feature throughout the orogen in this area. In addition the folds are accompanied by complex thrust faults and imbricates with a shallow to moderate southwesterly dip.

Structural studies in the Trygghamna-Lappdalen area of southern Oscar II Land reveal a variation in the geometry of the major folds, from asymmetric with wavelengths of up to 2 km, to typical chevron and box-like geometries. The movement along frontal ramps generated complex folds, stacked imbricate thrusts and associated backthrusts and backfolds within the Mesozoic (Triassic) cover. There is a clear genetic relationship between folding and thrusting where thrusts die out or pass along strike into major folds. Most of the imbricated thrusts developed by forelimb cut-offs of inverted major folds, with the imbrications producing numerous repetitions of sandstone-dominated Triassic formations in the area to the north of Erdmannflya. The Permian layers contain most of the mapped frontal ramps since these units are mechanically more competent, but flatten or sole out in the less-competent shaly Mesozoic formations, e.g. the Botneheia Fm and Janusfjellet Subgp. A major NE-SW-trending and essentially vertical strike-slip fault, the Isfjorden Fault (Challinor 1967; Harland & Horsfield 1974), separates highly deformed Mesozoic rocks to the northwest from the largely flat-lying Cretaceous/Tertiary rocks to the southeast on Erdmannflya and is interpreted as an oblique ramp structure (Bergh et al. 1988). The rocks adjacent to the fault (Cretaceous and Tertiary strata) are characterized by numerous

minor reverse faults, imbricate thrust sequences and tight upright folds with an axial planar cleavage. The throw on this fault is approximately 400 m based on the correlation of the Jurassic-Cretaceous boundary in the hanging-wall and footwall blocks. Bergh & Andresen (1990) proposed a model for the Paleogene structure of Oscar II Land whereby compressional deformation is transferred eastwards by a combination of fault propagation folding and thin-skinned d6collement thrusting. The western area can be considered a buried/blind thrust system. To the northeast the deformation style is typically that of an emergent thrust system with fault propagation folds and thrusts reaching the surface; similar structural styles are observed in Mesozoic rocks of Nordenski61d Land and along the Billefjorden and Lomfjorden fault zones of eastern Spitsbergen (Andresen, Bergh & Haremo 1994; Nottvedt et al. 1988). The implication is that a thin-skinned tectonic model can be applied to the West Spitsbergen Orogen in eastern Oscar II Land, in which orogenic stresses within the main part of the fold-and-thrust belt are transferred eastwards to the more central areas of Spitsbergen by regional d6collement or detachment beneath the Central (Paleogene) Basin (Nottvedt et al. 1988; Bergh & Andresen 1990).

9.7.4

The St Jonsfjorden area

The St Jonsfjorden area of West Spitsbergen lies within the Tertiary fold-and-thrust belt and has been studied by Horsfield, Kanat, Welbon & Maher (1992) and Maher & Welbon (1992). In the eastern part of the St Jonsfjorden area (Wittenburgfjellet to Klampen), Permian Kapp Starostin Formation cherts and limestones and the Triassic Sassendalen Group shales and sandstones form large northeast-vergent, close to tight folds within which smaller thrusts are common. Further west, Kapp Starostin Formation strata and underlying Gipsdalen Group strata are imbricated and form duplexes that underlie large-scale northeast-vergent monoclinal structures. Welbon & Maher (1992) summarized the St Jonsfjorden region, and supplement the earlier work of Horsfield. Mann & Townsend (1989) suggested a simple model whereby the St Jonsfjorden Trough formed in the hanging wall of the west-dipping fault zone, with the southern margin of the basin offset by a major NW-SEtrending transfer fault in Van Keulenfjorden. Vegardfjella and Wittenburgfjella (southeast end of St Jonsfjorden) are on the eastern edge of the basement high that parallels the west coast of Spitsbergen. Mapping (by Challinor & Horsfield, CSE) indicated a northeast-vergent thrust stack involving basement rocks and platform cover strata including Triassic units (Welbon & Maher 1992). Three major thrusts were defined by Maher & Welbon (1992) in the Vegardfjella-Wittenburgfjella area of inner St Jonsfjorden: the Lower Vegardfella Thrust, the Upper Vegardfjella Thrust, and the Vegardbreen Thrust (see also Welbon & Maher, 1992). This is a complex structure with units separated by the three thrusts mapped namely: Lower and Upper Vegardfjella thrust and the Vegardbreen thrust.

172

CHAPTER 9

Vegardbreen Thrust.

The Vegardbreen Thrust is the most prominent structure in the southern part of Oscar II Land. The thrust geometry is complex with significant Wordiekammen and Botheheia formation flats and a truncated, overturned fold limb with numerous minor structures in the eastern hanging-wall. The overall northeast dip is due to rotation above the underlying thrusts. The Vegardbreen Thrust was interpreted by Welbon & Maher (1992) to be the roof thrust with which the Upper Vegardfjella Thrust merged.

The repetition of Permian Kapp Starostin and Triassic strata to the northeast of Wittenburgfjellais mainly due to folding, but with the occasional development of minor thrusts; this is particularly evident at Klampen where six fold pairs are present. This zone of folding is about 8 km wide and was interpreted to have formed above a flat within the underlying Gipshuken Formation gypsum (Harland & Horsfield 1974; Maher 1988; Bergh & Andresen 1990). If this interpretation is correct, the eastern zone is clearly thin-skinned in character, which contrasts with the Vegard thrust stack where basement rocks are involvedin the thrusting and significant thrust ramps exist. Shortening across the Vegardfjella and Wittenburgfjella area was estimated to be about 13 km (Welbon & Maher 1992).

9.8

Structure of Prins Karls Forland

Whereas Oscar II Land exposes pre-Devonian and Carboniferous through Cretaceous strata, and so enables a distinction to be made between pre-Carboniferous and post-Early Cretaceous deformation, Prins Karls Forland lacks post-Silurian strata. Therefore suspected Paleogene deformation cannot be confirmed nor characterized by tectonism in younger strata. As in Oscar II Land, however, a post-Vendian pre-?Silurian tectonism sufficient to produce schistose and phyllitic lithologies, seen in the Sutorfjella conglomerate clasts in a turbidite sequence (Barents Formation), may correspond to the mid-Ordovician (Eidembreen) event in Oscar II Land. The structure of Prins Karls Forland has been investigated by many authors (e.g. Tyrrell 1924; Atkinson 1956, 1960; Harland et al. 1979; Hjelle, Ohta & Winsnes 1979; Morris 1982, 1989; Manby 1983a, b 1986; Dallmann et al. 1993; Lepvrier 1990). The structure reflects the stratigraphy trending and striking generally N N W - S S E parallel to the long axis of the island. Dips are often steep but the thickness of the strata generally yields broad outcrops. Distinct folds may be observed in E-W cliff sections with typical asymmetrical and occasional recumbent folds. Each investigation resulted in a different stratigraphic sequence which affected the structural interpretation and vice-versa. Despite the many uncertainties in Prins Karls Forland geology this author is reasonably confident in the essential correctness of the succession worked out by the Cambridge group as in Section 9.6. However, the ages of most units are uncertain.

9.8.1

Sequence and age of deformation

Because of the prevailing Caledonian deformation in much of Spitsbergen it was natural to assume that strong tectonism in older (unfossiliferous) rocks would probably be Silurian if not older. Atkinson (1956) described his structures as Caledonian without question or evidence. Harland & Horsfield (1974) in establishing the West Spitsbergen Orogen as a Tertiary entity included Prins Karls Forland (with the Pre-Carboniferous rocks of Oscar II Land) as zones (1 and 3) of probably Caledonian basement in which it was difficult to distinguish the effects of the Paleogene Orogeny so evident further east in Oscar II Land. Harland, Horsfield, Manby & Morris (1979) concluded an agreed stratigraphy based on work by Harland and Horsfield in Oscar II Land, then Harland followed by Manby and Morris in Prins Karls Forland. Tectonic interpretation was developed by individual authors.

Hjelle, Ohta & Winsnes (1979) covering the same area (Prins Karls Forland and Oscar II Land) concluded a Tertiary age of deformation of the island in conformity with that of the mainland. Manby (1986) described 'mid-Paleozoic metamorphism and polyphase deformation of the Forland Complex'. He assumed a Caledonian structure interpreted in three phases D1, D2 and D3. He did not distinguish which rock groups exhibited which characteristics nor did he specify the criteria by which D 1 and D2 could be distinguished, they being essentially homoaxial. Whereas D3 was a mild tectonism thought to be Tertiary, the conclusion on D2 was somewhat equivocal. Morris from his (1982) map plotted the en Ochelon Scotiadalen fault zone and concluded (1989) that 'the relatively simple geometrical relationships and the lack of secondary modification of the Scotiadalen fault zone argue against a Paleozoic origin'. The distributed shear zone is well orientated to accommodate shear strain developed during Tertiary time, and probably formed prior to the transitional phase of this deformation (Late Eocene to midOligocene, say 40-30 Ma; Steel et al. 1984; Lepvrier et al. 1988). Lepvrier (1990), possibly following Harland & Horsfield, assumed that his Tertiary graben structure adjoined Caledonian basement. The conclusion here, in conformity with interpretations of other parts of the western terranes is that there is some evidence for an early metamorphic post-Vendian, pre-Silurian phase which could be part of the mid-Ordovician Eidembreen event. It would thus only be seen in four lower groups and not in the Grampian Group and some of the D 1 characters as described by Manby could be of this age. No evidence is available of Silurian tectonism and it is concluded here that the main tectonism was part of the West Spitsbergen Orogeny of Eocene age.

9.8.2

Vergence of deformation

Whereas all agree that the structural trend is NNW-SSE, hence the linear shape of the island, the vergence could be either way towards the ENE or the WSW; it is not immediately obvious. Authors adopted one or other direction to conform with their overall interpretation. Thus Atkinson (1956) and Manby (1986) thinking the structure was Caledonian chose the westward vergence independently of the Paleogene eastwards thrusting on the mainland. On the other hand Hjelle, Ohta & Winsnes (1979), treating the island in conformity with Paleogene structures of the mainland, opted for an eastwards vergence as was followed, without discussion, for the northern part of the island by Dallmann et al. (1993). Figure 9.7 shows somewhat different interpretations of the same structures. Manby's sections show a thin-skinned tectonic d e v e l opment on a floor thrust not far beneath the surface. This author's prejudice has been towards a westward vergence and this need not be inconsistent with a Paleogene age as is discussed in Section 9.10.

9.8.3

Faulting

(a) Sequence of faulting. The Scotiadalen N-S Fault shown on most maps is not a major fault but a zone of minor en ~chelon faults trending N N E which, as Morris (1989) demonstrated, was a late event. A map of pre-Carboniferous groups of southern Prins Karls Forland is shown in Fig. 9.8. The island is crossed by many faults, typically ENE to ESE which appear to cut most structures including the boundary faults of the Paleogene graben. No systematic displacement has been noted. The principal single feature on the island is the boundary between the older deformed strata and the relatively undeformed Paleogene strata of the Buchananisen Group. The boundary appears to be one main fault or a series of stepped faults dipping steeply into the graben. It does, however, differ from north to south. Cliff sections north of

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CHAPTER 9 The re-emergence of the Prins Karls Forland Block was largely the result of extensional displacements along NNW-SSE-trending faults, along which there is also evidence for oblique-slip and pure strike-slip movement (e.g. Lepvrier & Geyssant 1984; Lepvrier 1990). Structural evidence for this is the presence of southeast-plunging folds in the Tertiary rocks of Prins Karls Forland. The generation and orientation of these folds can be explained by a resolved NE-SW principal compression (rl) of the rocks resulting in an overall northward movement of Prins Karls Forland with respect to mainland Oscar II Land. The latest identifiable events on the island are the broad E-W flexuring and ENE-WSW faulting of the Forland Complex and Tertiary infill, which resulted in the displacement of the main NNW-SSE-trending fault (Manby 1986).

(c) Structural units. In the north of the island the major thrusts were used first by Atkinson and then by M a n b y to define (respectively) five and four tectono-stratigraphic sub-areas. The map from M a n b y (1986) in Fig. 9.7 shows the named thrusts and sub-areas numbered. The sections are not altogether consistent with observed stratigraphy on the ground, but the overall style of deformation may well be correct.

Fig. 9.8. Lithostratigraphic formations and geological map of south-central Prins Karls Forland (adapted with permission from Morris 1982, 1989). Selv~tgen show typical normal faulting. However, at the northern tip of the island the boundary, whether or not faulted, shows vertical concordance between Grampian Group strata and indurated Paleogene strata. This indicates certainly that some Paleogene strata were involved in a compressive-transpressive phase and possibly that it is an up-ended parallel unconformity. If the latter, this would be no surprise in so far as mid- or late Paleozoic tectonism has not been established in the western terranes. The main boundary fault, generally steep to ?vertical appears to cut the folds and thrusts of the core of the island. The thrust faults all belong to the same homoaxial folded structure and have not been distinguished by age. The following hypothesis develops from (a) this author's prejudice for westward vergence of the thrusting, (b) the structure south of Scotiadalen according to the map of Morris (1989) and (c) the thin-skinned tectonic interpretation (in principle though not detail) as depicted by M a n b y (1986). It is conjectured here that the lower three groups exposed in the south of the island, being relatively competent, were folded in a simple anticline. The upper two groups were thrust westwards over this arch with d+collement in the incompetent Scotia Group. This would distinguish the thinskinned structures in the north. The break in the plan of the island suggests that the southern anticline might have continued northwards to the east had it not been downfaulted in the graben. (b) Strike-slip components. Dextral displacements in the Scotiadalen fault zone have been noted above (Morris 1989). Hjelle, Ohta & Winsnes (1979) referred to sinistral components but without localities. Possibly they had in mind the strong sinistral shear seen at Daudsmannsodden on the mainland (Harland et al. 1993). On the island some stones in the Ferrier Group tilloids are elongated possibly in the same sense. These and other indications cannot be dated directly. It is, however, generally accepted that the West Spitsbergen Orogeny resulted from Paleogene dextral transpression. Sinistral shear would fit the hypothesis of major Devonian strike-slip faulting which might have operated along the Forlandsundet Graben and so focused the Paleogene shear zone.

The principal feature of Manby's four (northern) units or subareas are as follows from the top down. Sub-area 4. A large part is formed of an uninverted Scotia-Grampian group succession in the upper limb of a large, essentially flat-lying F1 fold, the lower limb and core of which are truncated and replaced by the Northern Grampian Thrust (NGT). Sub-area 3. The central part of northern Prins Karls Forland is occupied by rocks of sub-area 3. In the north, this unit is covered by the Tertiary sediments of the Forlandsundet Basin and in the far north it is overthrust by the Northern Grampian Thrust (NGT). Structurally the rocks (Geikie, Peachflya and Scotia gps) form an inverted sequence in the lower limb of an F1 fold with an essentially fiat-lying anticlinal fold closing to the west; however, further south in the Selv~gen area, the strata around the F1 closure are right way up. Two prominent klippe structures are present to the north of Selvgtgen where they are infolded with Scotia Gp rocks. Sub-area 2. This forms a laterally extensive tectonic unit in north Prins Karls Forland, comprising rocks of the Scotia and Grampian gps. The rocks occur in a southward-plunging synform which verges southwest, with the rocks forming an inverted succession (Manby 1986). Conglomerates, stratigraphically equivalent to those in sub-area 1 have been more intensely deformed when compared with those in sub-area 1 with axial ratios greater than 6:1 aligned parallel to the major fold axis. Sub-area 1. This thrust sheet is the structurally lowest tectonic unit, lying beneath the Western Grampian Thrust (WGT), and largely consists of Grampian Group rocks; Scotia Group rocks are restricted to a small area to the north of this sub-area. The succession is uninverted with no evidence for stratigraphic repetition by minor thrusts. F1 folds range in size from microscopic to large-amplitude structures, e.g. the box or kink-like folds in the south of sub-area 1.

9.8.4

Metamorphic environments

Northern Prins Karls Land. The presence of biotite in the youngest exposed rocks of the Forland Complex indicates that the minimum metamorphic conditions reached were biotite grade (Manby 1983b). The stability of the chlorite-muscovite-quartzchloritoid assemblage in pelites, the absence of staurolite, cordierite or almandine garnet (in strata up to and including the Ferrier Group) suggest that metamorphic conditions remained within the greenschist facies and largely within the biotite grade. There is some evidence for higher temperatures in the Pinkie Group as shown by the higher aluminium content of some amphiboles and the presence of scapolite and oligoclase (Anl7), though this could be compositional; these rocks were also within the greenschist facies. According to M a n b y (1983b) the ambient conditions of prograde metamorphism prior to the start of D1 were within the 380-560~ and 4.0-7.5 kbar range, equivalent to geothermal gradients in the range 18-23~ -1. These are in broad agreement with data published by Ohta (1978) and Morris (1982).

CENTRAL WESTERN SPITSBERGEN Atkinson (1956) discussed chloritoid in the Forland. According to Manby (1986) evidencefor metamorphism occurring before D1 comes from the presence of randomly orientated and rosette clusters of chloritoid and other chloritoid crystals with rotational inclusion trails suggesting some syntectonic growth. However, non-aligned syntectonic mineral growth is not unusual. The phlogopites and chlorites overgrow S1 with minor pressure shadow development in sub-area 3 indicating that metamorphism continued late into D1. Manby (1986) suggested that the formation of the Forland Nappe closely followed the peak of metamorphism, the development of which was facilitated by the elevated temperatures and fluid phase activity.

Southern Prins Karls Forland. Metamorphism was first discussed by Tyrrell (1924) who identified chloritoid and muscovite referring the rocks to the biotite zone and the chloritoid as a stress mineral which Atkinson (1956) amplified as associated with the thrusting. Morris (1982) considered four compositions and described and interpreted their mineral assemblages: carbonates, pelites, psammites and mafics. The metamorphism accompanied or preceded the first recognisable structural event. Subsequent structures were not accompanied by metamorphism. Carbonate lithologies (>60% carbonate minerals) with dominant calcite, dolomite and quartz, with tremolite and epidote related to thermal (contact) metamorphism muscovite and chlorite. Consideration of possible mineral reactions suggest that it was low grade. Pelites (15-50% quartz, >25% Mg-A1-Fe silicates, <60% carbonate). Phyllosilicates (muscovite, biotite, chlorite and occasional chloritoid) are dominant with a variety of accessories and variable quartz. The rocks exhibit green-schist facies assemblages, similarly low grade. Psammites (>50% quartz). After quartz the above assemblages occur as minor constituents. Production of biotite implies a minimum temperature of 300~ Mafies (>15% quartz, >10% carbonates, >75% Mg-A1-Fe silicates) These are essentially found as metavolcanic flows, tufts, other pyroclastics and mixed with other sediments. Temperatures between 380~ (5 kbar) and 520~ (7 kbar) have probably obtained in retrograde metamorphism with degassing. In conclusion, thermal isograds approximately parallel the stratigraphic boundaries. Tectonic depth of metamorphism is, of course, highly relevant; but there is nothing to suggest more than a minor orogenic episode.

9.8.5

Conjectural synthesis

Whereas there is stratigraphic continuity between the northern and southern segments of the island, their structural characteristics are quite different. Of the five groups of formations the upper two are limited to the north, the lower two to the south and only the Peachflya Group is common to both (Fig. 9.8). The major deformation of the whole island is taken here to be part of the Paleogene West Spitsbergen Orogeny. Paleozoic (?Ordovician) tectonic episodes and possibly Devonian sinistral shear zones are probably recorded in the rocks but have yet to be clearly distinguished. The main features of Manby's D1, D2 and D3 would be Paleogene as affecting all groups of strata, whereas the Grampian Group would probably be post-middle Ordovician. Boudinage, rodding and mullion structures seen in the Ferrier Group might reflect the Eidembreen Event or Late Devonian shear. It is provisionally accepted that a westward-vergent Paleogene Orogeny folded the three lower groups in a coherent, competent anticline, with a possible bedding thrust above the oldest Ferrier Group rocks. The Scotia Group strata are conspicuously incompetent and provided for some d~collement over the lower groups. The map suggests that the northern thin-skinned structures slid westwards over the older rocks, but the northern continuation of the southern anticline is cut out by the Paleogene graben. The Scotiadalen shear zone with its mild deformation would have been protected from the overriding transpressive thrusting in the shadow of the lower anticline.

9.9

175

Structure of the Forlandsundet Basin

The structure and evolution of the Tertiary Forlandsundet Basin is not well understood, largely because of its location along the axial zone of the West Spitsbergen fold-and-thrust belt (Gabrielsen et al. 1990; Steel et al. 1990). The dimensions of the basin are approximately 30 km wide and 80 km long. The palaeostress history of the Forlandsundet Basin has been attempted (e.g. Lepvrier & Geyssant 1983, 1985; Lepvrier 1990).

9.9.1

Structure of the infill

Early Paleozoic rocks. The tectonic m~lange exposed in scattered outcrops in Kaffioyra and Sarsoyra has been interpreted as a sheared body of distinctive rock types, with Motalafjellet deep facies affinities (Ohta et al. 1995). The implication is that probable Ordovician rocks have been sheared dextrally northwards in a steeply dipping zone. The dextral shear would indicate a Paleogene transpressive phase probably preceding most of the Paleogene strata whose deformation is the subject of section 20.6.3.

Paleogene strata. In the area of Selvfigen (Prins Karls Forland), on the western side of the basin, Kleinspehn & Teyssier (1992) noted contacts where Palaeogene sediments rest on a pre-Devonian palaeo-regolith. This led them to question the concept of a simple extensional graben with several kilometres of dip-slip offset on the boundary faults (e.g. Manby 1986). The basin fill also shows multiple thrusts, strike-slip faults, open to tight folds, refolded isoclinal folds and foliated shears. Some high-angle fault surfaces display slickenside striations indicating normal slip. The strata show a dominant dip toward the basin axis, but are locally overturned; the age relationship between various structures has not been resolved. Clastic dykes with slickenside striations and softsediment folding were inferred to indicate that deformation was in part coeval with basin subsidence and deposition (Kleinspehn & Teyssier 1992). Other faults studied by them were found to have cut and displaced conglomerate clasts together with the adjacent matrix, indicating a high degree of lithification at the time of displacement. Several generations of cross-cutting brittle deformational structures have been defined from within single exposures, indicating a multiphase deformation history. Kleinspehn & Teyssier (1992) reported widespread evidence of ductile deformation in the Tertiary strata at SelvSgen, Buchananryggen and at Sarsoyra on both sides of the Forlandsundet Basin. It occurs within single exposures indicating multiphase deformation under different tectonic/thermal conditions. Petrographic studies of sandstone samples indicated the development of a foliation and the recrystallisation of micas. Strain is localised along narrow ductile shear zones along which a macroscopic foliation is evident; microstructural work has shown that the foliation is pervasive but poorly developed away from the shear zones. Karen Kleinspehn (in an oral presentation in Oslo in 1990), suggested that the presence of dynamically recrystallized chlorite was evidence of growth at or close to the brittle-ductile transition (i.e. at about 10-15 km depth), the inference being that the Forlandsundet Basin cannot be considered a simple upper crustal graben as previously documented (e.g. Steel et al. 1985). Manby (1990) argued that if the sediments were buried to such great depths then there would be evidence for a thermal event within the pre-Devonian basement rocks and resetting of radiometric ages in Prins Karls Forland. No evidence for such an event is known. Gabrielsen et al. (1992) also demonstrated that the basin-fill has suffered stronger deformation than previously assumed. Syndepositional deformation is inferred to have occurred locally, with the basin-fill affected regionally by mild folding and locally by more intense brittle deformation; two fold sets are defined. High-angle reverse faults are common in some parts of the basin; the basin clearly shows evidence for compressional deformation. Intense

176

CHAPTER 9

d e f o r m a t i o n is localized in areas that are characterized by the r a m p i n g o f thrust faults; several systems of late extensional fractures are developed (Gabrielsen et al. 1990). K l e i n s p e h n & Teyssier (1992) as well as Gabrielsen et al. (1992) confirmed that, f r o m the degree o f lithification, the deposits on the western side o f the basin were buried m o r e deeply than those on the eastern side. Limited vitrinite reflectance d a t a f r o m conglomeratic beds in the Selvgtgen area show significant variations on either side of the F o r l a n d s u n d e t Basin. Vitrinite reflectance values (R0) on the west side of the basin are in the range 2.55-5.50 with an average of R0 = 4.01; in contrast, 20 k m away at Sarsoyra, values o f R0 = 0 . 4 3 - 0 . 4 6 are indicated (Rye-Larsen in SKS 1995). This indicates significant differential subsidence a n d differing thermal histories over relatively short distances, with the Tertiary sediments on the west side of Prins Karls F o r l a n d having been buried to a substantial d e p t h and well b e y o n d the oil w i n d o w (anthracite to m e t a - a n t h r a c i t e coal rank).

9.9.2

Palaeostress history of the Forlandsundet Basin (phases 1-3)

A n analysis o f faults in the F o r l a n d s u n d e t Basin a n d their use in determining the principal palaeostress tensors, has shown a polyphase tectonic d e v e l o p m e n t of the basin (Lepvrier 1990); and c o m p l i m e n t s the w o r k of K l e i n s p e h n & Teyssier (1992), Gabrielsen et al. (1992) a n d N o t t v e d t et al. (1992). The tectonic synthesis o f Lepvrier (1990) led on from earlier studies of the West Spitsbergen O r o g e n (Lepvrier & Geyssant 1984, 1985), w h i c h c o n c e n t r a t e d on n o r t h w e s t Oscar II L a n d and the F o r l a n d s u n d e t Basin area. The later study indicated that the basin has suffered b o t h extensional and compressional phases, the m a i n details of which are summarised below. Still later was the interpretation of the zone o f intense transpressional strike-slip causing scattered exposures on Sarsoyra and Kaffioyra on the east side (Ohta et al. 1995).

Phase 1: transpressional event.

Preserved horizontal fault striations (Steel et al. 1985) relate to a phase of broadly NE-SW compression, the N20 transpressional event of Lepvrier (1990).

Phase 2: E N E - W S W compression. This event gave rise to the basinward dip of the Tertiary strata; it generated a general synformal geometry to the basin. Seismic data across the basin also indicate a general synform structure (Nottvedt et al. 1990). The maximum compressional stress tensor (al) has an azimuth of 070 080 ~. Deformation related to this compressional event can be correlated on both sides of the basin, where rare tight folds or thrust faults, similar to those in the West Spitsbergen Fold Belt, are recognized (Lepvrier 1990). A component of dip-slip movement towards the basin axis can be observed at some localities, conformable with the bedding dip; according to Lepvrier (1990) this demonstrates that strike-slip faulting preceded tilting and represents the earliest stage of deformation under this stress regime. Along the eastern margin of the basin the alluvial fan conglomerates of the Sarsbukta-Sarstangen formations are affected by two sets of strike-slip faults. In the area of Sarsoyra (near Kapp Graarud and Nyflua) a set of dextral (035-070 ~ and sinistral (100-130 ~ faults, steeply dipping to the south and north respectively, are present, with striations indicating a component of normal displacement, caused by the later tilting of the strata. Conglomerate pebbles are cut and display a 1-2cm lateral offset. The faulted contact of the Tertiary strata with the pre-Devonian basement at Kapp Graarud is defined by a sinistral strike-slip fault (130 ~ that was active during this phase. In the Sarsbukta section, similar sets of faults are present, but extension (NW-SE to N-S) is generally dominant and defined by oblique to normal fault striations (e.g. at Sarstangen). The analysis of the dextral shear zone affecting the Kaffioya Ordovician basement (Ohta et al. 1995) confirmed the earlier interpretations. A similar stress pattern is evident on the western side of the basin at several localities, determined as 075 ~ from the existence of two sets of transverse (relative to the basin trend) strike-slip faults; locally some pebbles of the SelvSgen Formation conglomerate are laterally displaced (Lepvrier & Geyssant 1985; Lepvrier 1990).

Fig. 9.9. Simplified structural map and cross-sections of the Forlandsundet Graben (from Gabrielsen et al. 1992).

Phase 3: E S E - W N W and N N W - S S E to N - S extensional phases. Faults related to each of these extensional phases are sometimes difficult to distinguish. However, the final NNW-SSE to N-S extension is well defined by oblique to dip-slip movements on the two sets of earlier strike-slip faults, associated with the ENE-WSW compression; this extension eventually becomes a prominent tectonic event. At Marchaislaguna, faults striking 060-075 ~ and 095-115 ~ cut N W S E to N-S faults and show oblique striations that are inferred to relate to an extension direction trending 167 ~.

9.9.3

Origin of the Forlandsundet Basin: current models

The F o r l a n d s u n d e t Basin presently appears as an asymmetric 'graben-type' structure b o u n d e d by high-angle dip-slip marginal faults (Fig. 9.9). However, the origin of the basin, located within the fold-and-thrust belt of the West Spitsbergen Orogen, is problematic. Several attempts have been m a d e to explain the subsidence of the F o r l a n d s u n d e t Basin within this compressive regime, that was d o m i n a t e d by N N W - S S E strike-slip faulting ( H a r l a n d &

CENTRAL WESTERN SPITSBERGEN

9.10

Fig. 9.10. Schematic diagram of 'flower structure' within a convergent strike-slip fault zone (reproduced with permission from Lowell 1972, fig. 9). Horsfield, 1974; Harland 1979, 1985; Lepvrier & Geyssant 1984, 1985; Steel e t al. 1985; Lepvrier 1990). Harland (1979) proposed a model comprising four tectonic phases to explain the development of the Forlandsundet Basin: (1) transpression; (2) transtension; (3) minor transpression; and (4) minor transtension. The first phase of transpression resulted in the compressional deformation that caused the uplift of the West Spitsbergen Fold Belt further east; this suggests that the extensional phases occurred late in the West Spitsbergen Orogeny. Steeply dipping Palaeogene strata adjacent to the West Forlandsundet Fault in Prins Karls Forland are cited as evidence of a third minor transpressional phase. These predominantly strike-slip episodes were related to horizontal movements along the Spitsbergen Fracture Zone. The palaeostress analysis of Lepvrier & Geyssant (1985), based on faults in the Forlandsundent area suggests that four tectonic regimes can be defined: (1) extension along NW-SE-trending faults related to 'graben' formation; (2) E-W transtension (pre-Oligocene); (3) ENE-WSW compression; and (4) NNW-SSE to N-S extension. They proposed that the graben subsided as a pull-apart basin between two right-stepping dextral strike-slip faults defined by the East and West Forlandsundet faults, shortly after the main Tertiary deformation along the West Spisbergen Fold Belt. It is accepted here that some graben formation preceded the transpression phase of Harland (1979). Steel et al. (1985), in contrast to the above models, proposed that the graben formed partly during and partly after the main phase of deformation along the fold belt, with two possible models suggested. The first model proposes that the basin formed in the lee of a left-stepping restraining bend to the north of Forlandsundet; in the second model the basin is envisaged as a collapse graben in the central part of the uplifted and arched orogenic belt. Additional evidence for the development of the Forlandsundet Basin within a strike-slip regime as a pull-apart basin comes from an analysis of the sedimentary sequences. In an extensional basin the initial rifting phase is normally followed by thermal subsidence giving rise to overlapping unconformities along the basin margins. The 'flower-structure' model as proposed by Lowell (1972) for the West Spitsbergen Orogenic Belt (see Fig. 9.10) has been commonly discounted (Manby 1988; Ohta 1988; Faleide et al. 1988) but deserves reassessment (Section 9.10) in relation to the origin of the Forlandsundet Basin (Steel et al. 1985) and in this work. Kleinspehn & Teyssier (1992) assessed two new hypotheses for the origin of the Forlandsundet Basin: (1) the basin formed as the result of extension and/or transtension followed by orthogonal shortening or strike-slip deformation, and (2) the basin originated in a compressional regime, piggy-back on top of the eastward-transported thrust sheets that formed the internal part of the orogenic zone. Folding and thrusting of the basin strata occurred first (e.g. Lepvrier 1988, 1990) followed by a period of extension, probably transtension, that generated the 'graben' structure that is observed at present.

177

A tectonic interpretation of the West Spitsbergen Orogen; northern segment

The West Spitsbergen Orogen (Harland & Horsfield 1974) north of Isfjorden is the study area of this chapter. In common with the orogen south of Isfjorden, Paleocene strata (in this study area the Ny-Alesund Subgroup) were deformed by the orogeny which was demonstrably post-Paleocene with an Eocene climax (Harland 1965). The cover sequence (Carboniferous through Albian) with its varied and distinctive strata facilitated, and indeed encouraged, the many structural studies of the thrust and fold belt comprising the eastern zone of the orogen. These studies demonstrated ENEverging thin-skinned thrust and fold structures over the Nordfjorden Block utilising incompetent Triassic shale and Permian evaporites. These same d~collement layers extended over the Billefjorden Trough (e.g. Harland, M a n n & Townsend 1988; Welbon & Maher 1992) and even to the Lomfjorden Fault Zone (Andresen e t al. 1992). The northernmost segment of the orogen swings round from the general N N W - S S E trend to N W - S E trend in Broggerhalvoya with vergence trending from E N E generally to N E and then to northerly thrusting with signicant crustal shortening. The northerly component of the dextral plate suture was thus severely constrained to the north and the simple early transpressive oblique transport was resolved into E N E compression seen in the eastern fold and thrust belt and strike-slip, notably in the Forlandsundet root zone. Much less attention has been paid to the western zones of the orogen where pre-Carboniferous basement prevails. It has been argued that these basement terranes along the west coast of Spitsbergen mostly expose (Precambrian) Varanger or older strata (Harland, Hambrey & Waddams 1993). However, north of Isfjorden Early Paleozoic strata are also exposed. The Early Paleozoic and Proterozoic rocks were all deformed by the Paleogene orogeny. Moreover the Eidembreen event, dated both istopically and biostratigraphically as mid-Ordovician preceded the Bullbreen Group strata in Oscar II Land (Chapter 14). The Grampian Group strata of Prins Karls Forland may correlate approximately with the Bullbreen Group. Both groups contain conglomerate with earlier metamorphosed clasts which could result from the Eidembreen tectonism. Both groups reflect unstable conditions and may be of Late Ordovician to mid-Silurian age. There is no Devonian outcrop in the study area. The main body of Svalbard to the east suffered major Silurian and minor Devonian tectonism, typical of the Caledonides: but so far no decisive evidence has been forthcoming for significant Silurian tectonism. Indeed it would be surprising if there were, because at this time the location of this terrane was probably nearer to that of Pearya in northern Ellesmere Island and far from the Iapetus-Caledonian developments. This accounts for the difficulty in distinguishing a Caledonian event in the detailed study by Morris (1989). This palinspastic arrangement is only part of the hypothesis of Harland & Wright (1979) that makes Svalbard a composite terrrane with this western province being joined by the central and eastern provinces by Silurian and Devonian sinistral strike-slip. The postulated Kongsfjorden-Hansbreen Fault Zone along which this docking took place is obscured by the later Carboniferous sedimentation and the Paleogene orogeny. However, such a fundamental fault may well have located the boundary between the Nordfjorden Block and the St Jonsfjorden Trough and also the subsequent boundary within the West Spitsbergen Orogen between the thrust and fold belt with its thin-skinned structures to the east and the deeper deformation to the west. The above hypothesis is retailed at this point to take account of some enigmatic problems discussed in the three foregoing sections. (a) In Oscar II Land Ratliff, Morris & Dodt (1988), in analysing the structure of the Bullbreen Group, argue for a N W - S E dextral shear zone with E N E verging thrust folds and not easily distinguished from the E N E verging Paleogene structures. Their argument that the structures were pre-Carboniferous is tenuous and, if mistaken, this structure is probably an integral part of the

178

CHAPTER 9

Paleogene orogeny with which the dextral transpression is consistent. Morris (1988) suggested that the later deformation involved northward, followed by easterly, directed thrusting. Thus two Paleogene phases may be distinguished here. (b) In Prins Karls Forland Manby (1986) could not in the end distinguish clearly between his D 1 and D2. He was expecting D 1 to be Caledonian and D2 to be Tertiary. In so far as some D1 structures deform Grampian Group strata it is possible that they should be D2 in his terminology. This would leave D1 for the schistosity and other fabrics in the Scotia and other earlier Groups that occur as pebbles in the Sutor Conglomerate. Making this assumption then the conspicuous D2 structures all verge to the SSW. (c) The Forlandsundet structure is no superficial graben. It has a complex history, with not only relatively porous and coal-beating strata in the later Balanuspynten Formation, but indurated vertical sandstones not easily distinguished from the subjacent Grampian Group strata in the northern cliff section of Prins Karls Forland. This would suggest that pre-orogenic as well as syn- and postorogenic Paleogene strata are preserved. (d) Putting these possibilities together, the model for the West Spitsbergen Orogen proposed by Lowell (1972) may again be considered with an axial-root zone for the orogen with WSW verging structures in Prins Karls Forland and ENE verging structures in eastern Oscar II Land. He also adopted the transpression hypothesis (Harland 1971) (Fig. 9.10) which is consistent with the plate-tectonic motions at that time. This model is consistent with the deep dextral Kaffioyra and Sarsoyra shear zone elucidated by Ohta et al. (1995).

On this basis a NNE-SSW dextral fault zone occupied Forlandsundet. (1) Paleocene transtension would have allowed deposition in a pull-apart basin. (2) During the main orogeny extreme transpression would have generated the steep thrusts along the axis, now mostly covered by water and late Paleogene strata, and pushed the strata outwards on each side to the ENE and WSW. (3) Late orogenic (Late Eocene) strike-slip continued with transtension and the development of the main pull-apart basin. In such a dynamic situation local and/or short term transpression complicated the depositional story. (4) The main dextral strike-slip may have continued without transpression or transtension into Neogene time. It might account for the large low flat area of Prins Karls Forland if it had been opposite Isfjorden when it was a wide valley. This speculation is an optional extra. However, the main dextral strike-slip was entirely taken up in faults west of Prins Karls Forland. The location of this Forlandsundet axis of the Orogen need be no surprise because of the location of the intense sinistral shearing of Vendian strata seen both in western Oscar II Land at Daudmannsodden, and in eastern Prins Karls Forland in the deformation of the tillite stones. That could have been part of the Eidembreen event but a Devonian age is preferred here. It is a fundamental fault zone with a long history. It fits the 'Tertiary orogen-parallel motion in the crystalline hinterland of Spitsbergen's fold-thrust belt' of Maher et al. (1997).

Chapter 10 Southwestern and Southern Spitsbergen W. B R I A N 10.1 10.1.1 10.1.2 10.2 10.2.1 10.2.2 10.3

HARLAND

with contributions with PAUL

Paleogene strata, 180

10.7.1

Calypsostranda Basin, 180 Oyrlandet Basin, 180

10.7.2 10.7.3

A. D O U B L E D A Y

Mesozoic strata in southwest Sarkapp Land, 182

Adventdalen Group, 182 Kapp Toscana and Sassendalen groups, 182 Permian and Carboniferous strata of southern Spitsbergen,

(W.B.H. & I.G.) 183 10.3.1 Kapp Starostin Formation (Tempelfjorden Group), 184 10.3.2 Tokrossoya Formation (Tempelfjorden Group), 184 10.3.3 Treskelodden (Reinodden) Formation (Treskelen Subgroup, Gipsdalen Group), 184 10.3.4 Hyrnefjellet Formation (Treskelen Subgroup, Gipsdalen Group), 186 10.3.5 Sergeijevfjellet Formation (Billefjorden Group), 186 10.3.6 Hornsundneset Formation (Billefjorden Group), 187 10.3.7 Adriabukta Formation (Billefjorden Group), 187 10.4 Devonian strata, 187 10.5 Proterozoic strata of western Nordenskiiild Land, 188 10.5.1 Sequence of the rock units, 188 10.5.2 Mineralization, 189 10.6 Proterozoic strata of western Nathorst and northwestern Wedel

10.7.4 10.8 10.8.1 10.8.2 10.8.3 10.9 10.10 10.10.1 10.10.2 10.11 10.12

& ISOBEL GEDDES

West of Hansbreen, 192 Early Paleozoic and Proterozoic strata east of Hansbreen, 194 Comparison of stratal schemes for southwest Wedel Jarlsberg Land, 195 Mineralization, 197 Early Paleozoic and Proterozoic strata of Sorkapp Land, 197

Early Paleozoic strata, 197 Neoproterozoic strata, 198 Mineralization around Andvika, 199 Correlation of pre-Devonian through southwest Spitsbergen, 199 Structure of western Nordenskiiild Land, 200

Eastern margin of the fold belt, 200 Main fold belt, 201 Structure of western Natborst Land, 201 Structure of Wedel Jarlsberg Land (W.B.H. & P.A.D.), 201

Neoproterozoic succession of northwestern Wedel Jarlsberg Land, 189 10.6.2 Proterozoic basement, 191 10.7 Early Paleozoic and Proterozoic strata of southwestern Wedel Jarlsberg Land, 191

10.12.1 10.12.2 10.12.3 10.12.4 10.12.5 10.12.6 10.13 10.13.1 10.13.2 10.13.3 10.13.4 10.13.5

This chapter treats that part of the West Spitsbergen Orogen south of Isfjorden (Figs 10.1, 10.2, 10.3). It follows the same pattern as the last in treating the stratigraphy of the area, then the structure. Southwestern differs from central western Spitsbergen in being of greater length, more stratigraphic variety but less pronounced Cenozoic deformation. This appears to decrease in intensity southwards. There is, moreover, a conspicuous contrast south of Isfjorden from a fold belt with many thrusts to one with less evident crustal shortening south of it. This correlates with the Central Basin to the east. The younger rocks vary in facies gradually enough to be treated together. They are, in effect, the western margin of the Central Basin the subject of Chapter 4. They are admirably described in the standard section for Svalbard at Festningen at the northern limit of the area, where the rocks of the cover sequence were overfolded and overthrust at the western limit of the basin in the West Spitsbergen Orogeny. They are seen well exposed in vertical strata in almost uninterrupted sequence. Of the younger rocks only the Calypsostranda Group is described briefly in Section 10.1 and the Oyrlandet Basin in Section 10.2 as they are isolated outcrops in the west. The Cretaceous and Jurassic strata are treated entirely in Chapters 4 and 5 and have no detail here. The Triassic strata may also be seen as an extension of the Central Basin and are so described in Chapter 4. However, the structural peculiarity in the south is worth noting again in this regional context and so has a small section (10.2). The Permian and Carboniferous strata extending beyond the Central Basin are described in Section 10.3. The small outcrops of Devonian strata in the south are described briefly in Section 10.4. The older rocks (pre-Devonian) have suffered three or more major tectonic episodes in Proterozoic, Paleozoic and Cenozoic time and it is often not easy to distinguish these in so far as the latest two, at least in the south, were both overthrust eastwards. The older rocks are also difficult to correlate and have received distinct nomenclature for each of four areas. The difficulty in correlation stems from differences of opinion. To avoid introducing

controversial assumptions at the initial descriptive stage in this investigation further nomenclature was introduced and has been followed to complete the independence of each descriptive area of strata between the areas and so to facilitate discussion of correlation at the end of the chapter. The differences of opinion on correlation present a problem for description of strata. It so happens that, especially in the southwest of the area (southwestern Wedel Jarlsberg Land and Sorkapp Land) the Polish group under the leadership of K. Birkenmajer have done the lion's share of the work and the early scheme established about 1960 has been continued and refined by that group. It has also been largely adopted by Norwegian, Russian and American groups. Therefore the initial description of strata will follow that scheme. However, the Cambridge group working independently and extending their correlation anticlockwise from the northeast of Svalbard came to different conclusions on reaching southwest Spitsbergen. Their interpretations were based in part on the opinion that in pre-Carboniferous time the different once distant terranes could lead to different correlations. Other work has also diverged. Therefore, alternative stratigraphic schemes have been formulated to challenge and modify the established scheme. Discussion of this challenge follows the descriptive sections which are arranged in areas to facilitate comparisons. Discussion of the West Spitsbergen Orogeny fold belt is similarly divided by Van Mijenfjorden, Van Keulenfjorden and Hornsund physically into four a r e a s - namely Nordenski61d Land, Western Nathorst Land, Wedel Jarlsberg Land, and Sorkapp Land. A distinctive feature of this sector of Spitsbergen is the occurrence of metallic sulphide minerals. They have been long known but only since about 1950 have they been considered systematically (e.g. Hjelle 1962; Birkenmajer & Wojciechowski 1964; Flood 1969; Czerny, Plywacz & Szubala 1992; Cerny, Kieres & Manecki 1992). With few exceptions they occur within Precambrian and entirely within pre-Devonian strata (Chapter 3.6.3). The only other economic exploration which resulted in a very limited coal mine was in the late Paleogene strata of Calypsobyen.

Jarlsberg lands, 189

10.6.1

Structure of the West Spitsbergen Orogen, 201 Postulated Silurian-Devonian strike-slip faulting, 204 Caledonian structures, 204 Jarlsbergian diastrophism, 204 Proto-basement deformation, 205 Post-proto-basement deformation of Precambrian rocks, 205 Structure of Surkapp Land (W.B.H. & P.A.D.), 205

The structural units, 205 Proterozoic structures, 205 Paleozoic structures, 206 Mesozoic structures, 207 Paleogene structures, 207

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CHAPTER 10

Key to numbered localities 1 2 3 4 5 6 7 8 9 10 11 12

Adriabukta 13 Barentsburg 14 Bredichinryggen 15 Brepollen 16 Burgerbukta 17 Calypsostranda 18 Elveflya 19 Fannypynten 20 Fridtjovhamna 21 G&shamna 22 Hansvika 23 Hyrne~ellet 24

Isbjornhamna KappMineral Konglomeratfjellet L~gnesbukta Linn60ella Linnevatnet Luciakammen Magnethogda Nottinghambukta Paske~ella Pulkovafjella Recherche~orden

25 26 27 28 29 30 31 32 33 34 35

Revdalen Rochesterpynten Samarinbreen Slyngfjellet Sofiekammen Treskelen Tsjerbysjovfjellet Van Muydenbukta Vimsodden Vrangpeisbreen Werenski61dbreen

Fig. 10.1. Topographic and place name map for Isfjorden to Sorkapp, based on Topographical Map o f Savlbard 1:500 000, sheet 1, Norsk Polarinstitutt.

10.1

Paleogene strata

T h e Paleogene strata belonging to the Central Basin, which b o u n d this study area to the east are treated in C h a p t e r 4. However, there is a faulted outlier, possibly a half-graben, on the coastline near K a p p Lyell. A n a l o g o u s to the F o r l a n d s u n d e t Graben, its stratig r a p h y is quite distinct f r o m that of the Central Basin. A n o t h e r possible half-graben is at Oyrlandet.

I0.I.I

Calypsostranda Basin

Calypsostranda Group (SKS 1995) comprises for the Tertiary strata of Renardodden (Thiedig et al. 1980) near Kap Lyell. Renardodden Fm (Thiedig et al. 1980) >217m. Mainly sandstone with occasional pebbles and coal fragments, some beds with ferruginous concretions. A basal conglomerate which rests on the Skilvika Fm. Skilvika Fm (Livshits 1967; Thiedig et al. 1980) 115.5 m. Mainly siltstones with some shales, thin sandstone beds and coals, also with coal pebbles, plant beds and a basal conglomerate which rests unconformably on the Rochesterpynten Fm. The age of the Renardodden and Skilvika formations had been determined as Oligocene by Livshits (1974) on the bases of pollen and spores and by Head (1984) and Manum & Throndsen (1986) as Late Eocene-Early Oligocene on the basis of dinocysts. Rochesterpynten Fm (Harland, Hambrey & Waddams 1993, p. 100). The description of this unit by Pickton & Harland in 1975 was inadvertently omitted from Thiedig et al. (1980). It comprises a tectono-sedimentary melange, formed largely of derived meta-diamictite blocks from the Kapp Lyell Group some of which are some metres across, probably resulting from collapse and slumping at an active fault scarp. There was possibly some induration event before deposition of the Skilvika Formation. These rocks were also described by Dallmann (1989). He extended an Inner Hornsund Fault Zone through Recherchebreen to make the Calypsostranda graben structure. He also noted the constituents of boulder conglomerates consolidated prior to 'Caledonian' metamorphism. He observed the effects of weathering of these blocks prior to the red-weathering and overlying sandstone horizon.

10.1.2

Oyrlandet Basin

O y r l a n d e t is the lower g r o u n d in s o u t h w e s t e r n m o s t Sorkapp L a n d west of the H o r n s u n d H i g h (e.g. Kistefjellet) at that latitude a n d east of the western fold zone of the West Spitsbergen Orogen at Oyrlandsodden. The only p r e - Q u a t e r n a r y rocks are tiny inliers of Paleogene strata towards the south and Cretaceous strata towards the n o r t h a n d also Paleogene coastal sections on the east side of Sommerfeldtbukta.

SOUTHWESTERN AND SOUTHERN SPITSBERGEN

181

Fig. 10.2. Generalized outcrop map of central and southwestern Spitsbergen, based on Harland, Hambrey & Waddams (1993), and Geological Map of Svalbard 1:100 000 sheets B9, B10, B11, B12 and C13. KHFZ, Kongsfjorden-Hansbreen Fault Zone. The Paleogene strata were regarded by Atkinson (1963) as an extension of the Central Basin. They are however separated structurally by the Hornsund High though Paleogene strata may once have extended throughout the area. It is now a distinct small basin bounded to the southwest by Tempelfjorden Group strata and to the east by a fault so it may be regarded as a half graben or graben. It is based on the diagrammatic map in Dallmann et al. (1993) as the Oyrlandet Graben. The fullest account is by Dallmann et al. (1993) who reported that whereas the Firkanten (Barentsberg) Formation is c. 140150 m thick to the east it may reach 300 m in the Graben. The most complete exposures appear against the eastern fault of the graben on the east coast of Sommerfeldtbukta. It is divided into three members, which are also recognizable in the outcrops to the east, following Kalgraff in Steel et al. (1981). Firkanten Fm ?c. 300. Endalen Mbr, 200+m comprises immature, light grey, porous fine- to medium-grained sandstone with coaly flakes and flazer bedding. Dark grey quartzitic sandstones and silty shales are interbedded. Kolthoffberget Mbr, c. 20+m of black or dark grey silty shales with brownish red-weathering colours and spheroidal cleavage. It weathers characteristically into small steep incised valleys only a few metres deep. Todalen Mbr, c. 30m of bioturbated, occasionally ripple-marked finegrained sandstones with plant remains and occasional coal seams. There is a (?basal) gravel conglomerate.

182

CHAPTER 10

Fig. 10.3. Simplified tectonic map of central and southwestern Spitsbergen.

10.2

Mesozoic strata in southwest Sorkapp Land

The Mesozoic stratigraphy of Svalbard is very largely treated in Chapters 4 and 5 so that the western margin of the Central Basin practically defines the artificial division between Chapters 4 and 10.

10.2.1

Adventdalen Group

The Adventdalen Group (Cretaceous-Jurassic) strata extend in a SSE direction within the main (eastern) fold and thrust belt of the West Spitsbergen Orogen. This reaches the southern shore of Sorkapp Land east of Mathiasbreen and, in effect east of the Hornsund High (see below). On the Hornsund High, at Kistefjellet, Janusffjellet Subgroup strata rest at the summit on Triassic strata which rest directly on folded Precambrian rocks. Further west and occupying low ground corresponding to Sommerfeldtbukta is the Oydandet plain just above sea level and exposing only small patches of pre-Quaternary strata. These include the Oyrlandet Paleogene and some exposures of the Cretaceous Helvetiafjellet Formation. Whether the basin contains a fuller Mesozoic succession is uncertain.

10.2.2

Kapp Toscana and Sassendalen groups

The Kapp Toscana and Sassendalen groups have been described generally in Chapters 4 and 5 as there is sufficient uniformity o f facies throughout the outcrop area in Spitsbergen for the strata most conveniently to be treated together as in Chapter 4. This southwestern sector of Spitsbergen contains contrasting successions between northern and southern Triassic outcrops.

(a) The northern outcrops. From Nordenski61d Land to northern Wedel Jarlsberg Land are exposed the thickest Triassic developments in Svalbard. Their extension to the west has been lost to erosion after the Paleogene folding and uplift. The succession from the Festningen coastline to southern Nordenskirld Land, Nathorst Land and Western Wedel Jarlsberg Land is relatively uniform and is summarized here.

Kapp Toscana Gp Wilhelmoya Fm. The overlying 'Lias' conglomerate (Brentskardhaugen Bed), taken in this work as the base of the Janusfjellet Subgroup of the Adventdalen Group, extends throughout this sector, the underlying Wilhelmoya Fm is generally about 5 to t0m in the northrn development but may thicken in the southern succession to about 25 m and up to 75 m (Worsley & Mork 1978).

SOUTHWESTERN AND SOUTHERN SPITSBERGEN

De Geerdalen Fm. This typical sandstone facies forms the bulk of the main northern development reaching a thickness of 327 m at Festningen and about 200 m at Van Keulenfjorden. Tschermakfjellet Fin. Whereas this distinctive marine facies is established as a formation it is not noticeable in this northern thicker development but develops in the south up to about 25 m (Worsley & Mork 1978). Sassendalen Gp Botneheia Fro, 210 m (thinning south to 8 cm at Kistefjellet). It is from this section at Bravaisberget (in SW Nathorst Land) that Mork, Knarud & Worsley (1982) renamed the Botneheia Fm (Birkenmajer 1977). Worsley & Mork (1978) divided the formation into two members. Somnovbreen Mbr is coarser grained in which silstones dominate shales. Passhatten Mbr is typical of the Botneheia Fm in the Central Basin with soft black, often bituminous shales with thin siltstone interbeds containing phosphatic nodules. Sticky Keep Fro, 220m up to 278m at Bravaisberget and thinning southwards to 110m. Similarly from the section at Festningen, at the southern entrance to Isfjorden, Mork, Knarud & Worsley (1982) renamed the Sticky Keep Fm at Tvillingodden where it also crops out. It is typically a coarsening-upward unit of siltstones and sandstones with shales. In Bellsund brachiopod-bearing limestones (the Retzia Limestone of Lundgren, 1887) are well known and occur near the base of the formation, possibly correlating biostratigraphically with beds in the underlying formation but occurring in the basal shales of the Sticky Keep Fm. Vardebukta Fm, 290 m thinning southward to 70 m. This formation also becomes coarser near the top where sandstones contrast with the overlying shales. At the bottom the top shales may rest on the resistant Kapp Starostin Fm and are typically obscured. The upper sandstones are cross-bedded, often with carbonate cement and with infilled burrows. In the south two members were proposed (Birkenmajer 1977) which may be the equivalent of the lower (Selmaneset) Member established at Isfjorden (Buchan et al. 1965).

(b) The southern outcrops. The s o u t h e r n outcrops f r o m s o u t h e r n W e d e l Jarlsberg L a n d s o u t h w a r d s are distributed over a complex structural terrane in w h i c h four zones f r o m east to west have been recognized. Thicknesses reduce to less t h a n h a l f that at Festningen. (i) The southern extension of the foldbelt. In the east the familiar stratigraphical relationships within the fold belt c o n t i n u e southwards. (ii) T h e Hornsund H i g h is distinguished by relatively flattying Triassic strata resting u n c o n f o r m a b l y on, a n d truncating, d e f o r m e d P r e c a m b r i a n a n d Early Paleozoic strata. T h e earliest Triassic strata are Dienerian a n d the reduced V a r d e b u k t a a n d Sticky K e e p f o r m a t i o n s are distinguishable, b u t n o t so easily. Therefore M o r k , K n a r u d & Worstey (1982) i n t r o d u c e d the n a m e Kistefjellet F o r m a t i o n to c o m b i n e these two units a n d c o n t i n u e d the easily recognisable B o t n e h e i a F o r m a t i o n using their n a m e (Bravaisberget) for the f o r m a t i o n . In s u m m a r y the succession in zone (ii) is:

Kapp Toscana Gp. As indicated in the northern part of this sector where the De Geerdalen Formation comprises almost the whole of the Group in its thicker development these southern successions contain significant thicknesses of all three formations for example at Treskelen in Hornsund and Kistefjellet in southern Sorkapp Land thicknesses respectively are (Worsley & Mork 1978) Willkelmoya Fm, 20 m and 35 m De Geerdalen Fin, t 15 m and 30 m Tschermakfjellet Fin, 250m and 12m Sassendalen Gp Botneheia Fm is an upward-coarsening sequence divided into three members. Somnovbreen Mbr of fine bioturbated sandstones with carbonate cements. Karentopgen Mbr develops locally (up to 43 m) is of coarse-gained planar cross-bedded sandstones, with conglomerates and large channel-fill structures which indicate sediment transport to the east and southeast. Passhatten Mbr is of dark shales with the characteristic phosphatic nodules of the Botneheia Fm with middle Triassic fossils. Kistefjellet Fin, 38 m. This formation combined the Upper Vardebukta and the Sticky Keep fms in this new name by Mork et al. (1982). Mork & Worsley (1979) had redefined the Brevassfjeltet conglomerate of Birkenmajer (1977) which corresponded approximately to the Vardebukta Fm as below.

183

The main body of the formation is of interbedded fossiliferous shales and medium to very fine sandstones which may contain ripples or carbonate cement. This would correspond to the Sticky Keep Fm. The Vardebukta unit is distinguished by conglomerate beds at the top and base. At the top is the Urnetoppen (conglomerate) Mbr and at the base is the Brevassfjdlet (conglomerate) Mbr. This is a basal conglomerate resting on deformed and truncated Precambrian and Early Paleozoic strata on the Hornsund High. It extends to the west, zone (iii), where it rests on Carboniferous strata. Its age is Dienerian to Spathian or even early Anisian (Mork & Worsley 1979). (iii) West of the H o r n s u n d High, a n d west o f the s o u t h e r n extension o f the H a n s b r e e n F a u l t Z o n e is a wide o u t c r o p of C a r b o n i f e r o u s strata, m a i n l y sandstone, which are relatively fiat-lying. O n these rest the Brevassfjellet c o n g l o m e r a t e s with little obvious discordance. H o w e v e r , the w h o l e o f zones (i) to (iv) have suffered Paleogene tectonism and whereas in zone (i) the Triassic overlie Permian, C a r b o n i f e r o u s a n d D e v o n i a n strata a n d are infolded with them, in zone (ii) they have suffered only relatively horizontal bedding thrusts which are still m o r e obvious in zone (iii). (iv) S o r k a p p o y a a n d T o k r o s s o y a are islands to the SSE o f O y r l a n d s o d d e n the s o u t h e r n m o s t tip o f Spitsbergen w h e r e the Triassic strata are steeply infolded with a p p r o x i m a t e l y c o n c o r d a n t K a p p Starostin F o r m a t i o n strata. T h e strike of these structures, extended n o r t h w a r d s , passes in a N N W - S S E direction t h r o u g h T o k r o s s o y a , O y r l a n d s o d d e n tangentially offshore to the rest o f S o r k a p p L a n d a n d Wedel Jarlsberg L a n d a n d so represents a western fold belt in the West Spitsbergen Orogen. Just to the northeast o f this foldbelt is the small g r a b e n basin of O y r l a n d e t already referred to above.

10.3

P e r m i a n and Carboniferous strata o f southern Spitsbergen

In s o u t h e r n Spitsbergen Late Paleozoic strata occur within the Tertiary fold-and-thrust belt. T h e y are exposed in a thin bett trending N N W - S S E f r o m Akseloya across the western tip o f N a t h o r s t L a n d , across eastern Wedel Jarlsberg L a n d into central S o r k a p p L a n d . Exposures also occur in a separate, small, belt at the s o u t h w e s t e r n tip o f S o r k a p p L a n d a n d extend across to Sorkappoya. T h e C a r b o n i f e r o u s evolution o f the region was c o n t r o l l e d by the presence o f t w o b a s e m e n t highs: the W e d e l Jarlsberg L a n d H i g h a n d the S o r k a p p - H o r n s u n d High. O n the n o r t h side o f the f o r m e r lay the St J o n s f j o r d e n T r o u g h extending f r o m O s c a r II L a n d into Nordenski61d L a n d a n d N a t h o r s t L a n d . H e n c e the rocks in those areas share C a r b o n i f e r o u s stratigraphic n o m e n clature a n d are all described in C h a p t e r 9. Between the two b a s e m e n t highs lay the I n n e r H o r n s u n d T r o u g h , c o n t a i n i n g m o s t o f the rocks described in this section. S o u t h o f the S o r k a p p H o m s u n d H i g h there p r o b a b l y lay a n o t h e r basin, but the resultant sediments are n o t well exposed or described. P e r m i a n rocks b l a n k e t e d the region including the highs, such that the K a p p Starostin F o r m a t i o n can be traced into the area. H o w e v e r , it is n a m e d s o u t h o f the H o r n s u n d H i g h as the T o k r o s s o y a Formation. As elsewhere in Svalbard, the rocks fall into the three groups, as follows.

lh?msow Land Supergp Tempelfjorden Gp Kapp Starostin Fin (correlated with the) Tokrossoya Fm Gipsdalen Gp Treskelen Subgp Treskdodden Fin HyrnefjeHet Fin

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CHAPTER 10

Billefjorden Gp Sergeijevfjellet Fm Hornsundneset Fm Adriabukta Fm E a c h is described below.

10.3.1

Kapp Starostin Formation (Tempelfjorden Group)

T h e K a p p S t a r o s t i n F o r m a t i o n (defined in C h a p t e r 4) is best d e v e l o p e d in n o r t h e r n a n d central Spitsbergen, as it thins a n d d i s a p p e a r s s o u t h w a r d s in S o r k a p p L a n d . H o w e v e r , it did f o r m o n the W e d e l Jarlsberg L a n d High, e x t e n d into the I n n e r H o r n s u n d T r o u g h a n d o n to the H o r n s u n d H i g h , s o u t h w e s t o f w h i c h it was named Tokrossoya Formation. From Nathorst Land (Midterhuken) the Kapp Starostin Fm thins from 385 m to 150 m at Zittelberget in Wedel Jarlsberg Land/Torell Land. There, the three main divisions of the formation can be recognized (Dallmann e t al., B11G, 1990) as follows. The upper Hovtinden Mbr, 80-215m of chertified siltstones and very finegrained sandstones with glauconite, as well as pure spiculitic cherts. The Svenskeegga Mbr, 60-160m contains sandy, sparry limestone with abundant fossil remains, interbedded with some sandstones, rounded quartz and chert-pebble conglomerates and pure chert layers. Some of the limestones show cross-bedding which indicates a variety of current directions. There is also a thin lignite horizon interbedded with the limestones at one locality. The lowermost Voringen Mbr is barely distinguishable, containing only 6-12 m in the north of calcitic fossiliferous packstone. In northern Wedel Jarlsberg Land the sections at Reinodden were described with biostratigraphic detail by Nakazawa et al. (1990). In particular the three members of the Kapp Starostin were characterised in successive beds. Of most interest is their uppermost fossil records from the Hovtinden Member which they correlate with the Chinese sequence where late Permian biotas are better represented and argue Late Leonardian and Early Roadian ages (Ufimian into Wordian). This leaves Capitanian and Lopingian time not recorded. Southwards, the lower two of the three members appears to die out towards the Hornsund High, with a notable decrease in thickness. At Treskelodden (Hornsund), the uppermost Hovtinden Mbr lies directly on the Treskelodden Fm, cutting out the entire Gipshuken Fm. Calcareous siltstones are underlain by basal conglomerates which were deposited on different units of the Treskelodden Fm and infill karst surfaces in the limestones. About 12km further south, the Kapp Starostin Fm is even thinner, only 5.5m at Austjokeltinden. There, fossiliferous, glauconitic, calcareous siltstones, sandstones and limestones occur, with repeated conglomerates and lags containing abraded phosphatic steinkerns, lie on the Treskelodden Fro. There appears to be only one possible explanation to the generalization that in Wedel Jarlsberg Land west of Recherchebreen, Paleozoic through Mesozoic strata are not recorded. The exception would be the blocks of Kapp Starostin facies inland of Calypsobyen near the snout of Scottbreen (Kowallis & Craddock 1982). These are few and limited to a small area, but flat-lying and not tectonized. If they are not erratics they might suggest (i) that mid-Permian rested unconformably on Vendian strata and (ii) that the deformation evident in the Kapp Lyell strata was earlier. Neither conclusion can be certain because the Kapp Starostin Formation is remarkably strong.

10.3.2

Tokrossoya Formation (Tempelfjorden Group)

In s o u t h w e s t e r n S o r k a p p L a n d this f o r m a t i o n c o n t i n u e s the K a p p S t a r o s t i n F o r m a t i o n , w i t h w h i c h it has m a n y similarities. It is at least 400 m thick, a l t h o u g h the base a n d t o p are n o t seen. It consists o f cherts, limestones a n d arenites with an a b u n d a n t f a u n a w h i c h indicates a K u n g u r i a n - W o r d i a n age. It coarsens u p w a r d s overall, a n d was p r o b a b l y d e p o s i t e d in a m a r g i n a l m a r i n e e n v i r o n m e n t . This formation, first described by Siedlecki (1964), consists of sandstone, limestone and chert which occurs in the extreme southwest of Sorkapp Land and on the offshore islands. It was the lateral equivalent of the Kapp

Starostin Fm, preserved in a separate basin southwest of the Hornsund High. It is included as a member within the Kapp Starostin Formation by some authors; for example in the map of Sorkapp (Dallmann et al., CI3G, 1993; Winsnes et al. 1993). The formation consists of about 50% cherts, 30% limestones and 20% arenites of essentially the same lithologies as the Kapp Starostin Fm (see above). Two divisions have been recognized. Fossils are plentiful, but few have been described specifically from this formation. Malecki (1968) described bryozoans, and brachiopods also occur. The fauna correlates with the Kapp Starostin Fm (Malecki 1968). In the earlier description (Siedlecki 1964) the sequence was thought to be the other way up, so Siedlecki's Upper Tokrossoya Beds are equivalent to the Lower Mbr described here. Upper Mbr. This consists of over 200 m of interbedded limestones and arenites containing an abundant, but rather restricted fauna of productids and spiriferids, with two distinct bryozoan horizons. Lower Mbr. This is relatively poorly fossiliferous and consists of 200 m of massive, dark-coloured cherts which are resistant to weathering. On purely lithological grounds, the more arencaceous Upper Mbr may correlate with the Hovtinden Mbr and be of Late Ufimian-Wordian age. The Lower Mbr would then correlate with the Svenskeegga and Voringen mbrs and be of Kungurian-Ufimian age.

10.3.3

Treskelodden (Reinodden) Formation (Treskelen Subgroup, Gipsdalen Group)

T h e T r e s k e l o d d e n F o r m a t i o n was defined in the H o r n s u n d n e s e t area, a n d its equivalent, the R e i n o d d e n F o r m a t i o n was described f r o m Bellsund. S K S ( D a l l m a n n e t al. 1996) has ruled t h a t the T r e s k e l o d d e n F o r m a t i o n , h a v i n g priority ( B i r k e n m a j e r 1959) s h o u l d apply to b o t h . T h e rocks at R e i n o d d e n were described as n a m e d by Orvin (1940) a n d b o t h units were described as n a m e d f o r m a t i o n s by Cutbill & C h a l l i n o r (1965) a n d N y s a e t h e r (1977). It c o n t a i n s cyclic sequences o f yellow, red or b r o w n s a n d s t o n e c o m m o n l y c r o s s - b e d d e d , c o n g l o m e r a t e with q u a r t z a n d chert clasts, limestone sparry or sandy, a n d d o l o s t o n e , c o m m o n l y with p l a n t f r a g m e n t s a n d desiccation cracks at the top. Lateral facies v a r i a t i o n is a characteristic o f the unit, with s a n d s t o n e s c h a n g i n g laterally into l i m e s t o n e or c o n g l o m e r a t e which f o r m only a small b u t significant p r o p o r t i o n o f the total, increasing in i m p o r t a n c e to the south. T h e f o r m a t i o n shows evidence o f d e p o s i t i o n in b o t h m a r i n e a n d terrestrial settings, p r o b a b l y in a n alluvial system at the base a n d a fan delta for the r e m a i n d e r . Tidal channel, intertidal, offshore bar a n d l a g o o n a l facies are all represented. There was an increasing m a r i n e influence u p w a r d s t h r o u g h the f o r m a t i o n . T h e limestones c o n t a i n an a b u n d a n t f a u n a , a l t h o u g h the age is n o t tightly defined. It is p r o b a b l y Late C a r b o n i f e r o u s (Gzelian) to Early P e r m i a n ( A s s e l i a n - S a k m a r i a n ) . (a) Hornsund. The Treskelodden Fm consists of rhythmically deposited sandstones, conglomerates, limestones and dolomites. There is rapid facies variation from west to the east which is complicated by overthrusting during Tertiary deformation. The lower 20-50m appear to be unfossiliferous, in contrast to higher levels which are rich in fossils, notably corals. Nysaether (1977) attempted a litho-correlation of the lower unit of his 'Drevbreen beds' with the upper Treskelodden Fm which he considered is their partial lateral equivalent and downward continuation. He correlated the latter lithostratigraphically with his Reinodden Fm. The type section is at Treskelodden, Hornsund, where the sequence is 129 m. The formation has a limited outcrop, largely confined to inner Hornsund, although some outcrops occur inland; in west-central Torell Land it is 185 m at Polakkfjellet where the top of the formation can be seen. It appears to thin rapidly onto the Hornsund High and is only 50 m at Kopernikusfjellet and 70 m at Urnetoppen. South of Hornsund, 280 m of coarse clastics at Bautaen possibly belong to the Treskelodden Fm and the formation appears again further south at Ausjokeltinden where 125 m are exposed (Hellem & Worsley 1978). To the east it is obscured by younger strata and northwards it seems likely that this facies is replaced by carbonate of the Tyrrellfjellet Mbr (Wordiekammen Fm). The upper boundary is the unconformity below the siliceous Hovtinden Mbr of the Kapp Starostin Fm. In the Hornsund area, the Hovtinden Mbr is cut out westward by the Triassic unconformity and locally Triassic shales rest on the Treskelodden Fm. There is evidence of erosion on the top surface

SOUTHWESTERN A N D SOUTHERN SPITSBERGEN of the uppermost beds. However, at Polakkfjellet the top can be seen to be conformable beneath the Gipshuken Fm which has not been eroded here (Birkenmajer 1977, fig. 15). According to Birkenmajer (1984), the lower boundary is unconformable on the red conglomerates and sandstone of the Hyrnefjellet Fro, which is probably of Carboniferous age. Prior to Birkenmajer's detailed account, the lower boundary was considered to be transitional to the Hyrnefjellet Fm, which, except for the colour, is lithologically similar to the lower Treskelodden Fm. Sandstones make up the bulk of the formation (60%). They are commonly calcareous, and in the upper part are closely interbedded with, and pass laterally into, limestones. They are hard, compact, and generally well-sorted, but conglomeratic lenses and layers are common. Large colonial and solitary corals are present. Cement is usually calcite or quartz. In the lower part sandstones pass westwards into conglomerates. There are some ferruginous horizons. South of Hornsund, the sandstones become increasingly conglomeratic and they pass into conglomerates, which make up about 10% of the whole formation. Thin bands of extremely heterogeneous, poorly rounded and sorted conglomerate contain pre-Devonian and possibly Early Carboniferous pebbles. The conglomerate of the lower part of the formation consists of quartz and pre-Devonian pebbles with fair sorting and rounding. In the structural unit south of Hornsund, over 200m of texturally mature, grain-supported, massive quartz conglomerate occurs. Its base is not seen and it is overlain by Early Triassic rocks, (possibly overthrust), so its relationship to the rest of the Permian sequence is not known. Gjelberg & Steel (1981) described it as the 'Bladegga conglomerate', underlying the Hyrnefjellet Fm and considered it to belong to the Carboniferous sequence. Further south still, at Austjokeltinden in Sorkapp Land, 125m of Treskelodden F m are exposed beneath the Kapp Starostin Fm, consisting of conglomerates, sandstones and minor shales. A fossiliferous horizon here is the uppermost shale, which contains corals (Hellem & Worsley 1978). The fossiliferous limestones constitute 25% of the formation and appear in the upper part as thin interbeds in the predominantly arenaceous sequence. They contain large coral colonies, solitary corals and brachiopods. At the top of the formation a thicker limestone occurs. The limestones are generally grey calcarenites and biocalcarenites, and may grade into calcareous sandstone. There are some horizons of dolomite and thin red shale. The rocks are arranged in predominantly upward-fining cycles on both a large and small scale, described in detail by Birkenmajer. Fossiliferous (coral-bearing) conglomerates and biogenic limestone are generally confined to the base of the cycles. They usually show sharply delimited erosional bases and commonly begin as channels cutting into the top part of the preceding cycle. The middle part of the cycle is dominated by calcareous sandstone and quartzite, with large-scale planar cross-bedding and subordinate conglomerates. The tops of many cycles are characterized by fine sediments with plant fragments and desiccation cracks. This part of the cycle is commonly missing in many cases due to intraformational erosion. Some dolomitic limestone or dolomite intercalations, devoid of fossils, occur in the highest parts of the formation, near the evaporites of the overlying Gipshuken Fro. At Svartperla, in the northeast of the area, 200m of deformed limestones were recorded by Birkenmajer (1964). This possibly suggests that there is a gradation into limestones in this direction. Palaeontology and age. The upper two thirds of the formation contains a diverse fauna including abundant brachiopods, and corals as well as trilobites, bryozoans, crinoids, bivalves, gastropods, nautiloids, foraminifers, trace fossils of marine worms, calcareous algae and land plant detritus. The lower part is unfossiliferous, except for indeterminable plant remains. Czerniecki (1969) concluded that the brachiopod assemblage has a Gzelian age although comparison of his species with those listed by Gobbett (1964) shows a much closer comparison with the ~Tyrrellfjellet Mbr (Asselian/Sakmarian) that had already been noted by Gobbett. The limestones in the upper part of the formation contain an abundant redeposited coral fauna, which was described by Fedorowski (1965, 1967) and Birkeumajer & Fedorowski (1980). This fauna is quite different from that of the Carboniferous Cadellfjellet Mbr which is beneath the Tyrrellfjellet Mbr and would seem younger. This supports evidence from the brachiopods. The fauna is dominated by the typically Permian genera Wentzelella and Londaleiastraea, and as Sakmarian species, common to the Tyrrellfjellet Mbr, seem to form a relict group; the age was revised to earlier Permian. The corals resemble Early Permian rugose corals of the Arctic Province. They also show an affinity to those of the Hambergfjellet Fm (Sakmarian-Artinskian; Fedorowski in Simonsen 1987).

185

Of the trilobites present, the Ditomopygae species has a close relative in the Gzelian Stage of Russia. A gastropod reported by Karczewski (1982) is very weak supporting evidence for a Permian age. A number of foraminifers were identified by Liszka (1964). Unfortunately, index fusulinids are lacking, and no direct comparison with the zones of Cutbill & Challinor can be made. The assemblage resembles the Asselian/ Sakmarian Schwagerina and Tastubia zones of the Urals. Nysaether (1977) from a litho-correlation with his Drevbreen beds, made the upper Treskelodden Fm equivalent to the lowermost Drevbreen beds in which he found Late Carboniferous (Gzelian) foraminifers. However, the fossil evidence make it seem more likely that the fossiliferous part of the Treskelodden Fm is laterally equivalent to the middle and upper Drevbreen beds and also the Tyrrellfjellet Mbr which are probably all early Permian in age. The lower, unfossiliferous beds may belong to the Late Carboniferous period. The presence of bioherms in the upper part was mentioned by Birkenmajer (1984); This provides a link with the lower Tyrrellfjellet Mbr and the Kapp Dun6r Formation of Bjornoya.

(b) Bellsund (e.g. at R e i n o d d e n ) The succession consists of alternating sandstones, siltstones, limestones and dolomites with subordinate amounts of conglomerates and shales, of which terrigenous clastics make up about 75% and carbonates 20% (Nysaether 1977). A more or less cyclic pattern is present, starting with carbonate followed by generally upward-coarsening clastics. The formation occurs below the Gipshuken Fm from Bellsund southwards until it is cut by the unconformity below the Hovtinden Mbr of the Kapp Starostin Fm. Nysaether (1977) correlated the formation at Ahlstrandodden with the Drevbreen beds which he described at Drevbreen in Torell Land. The formation is generally about 200 m thick, but on Kopernikusfjellet, only 15km south of Zittelberget, where it is of similar thickness, the formation is represented by only 35 m of conglomerate. Moreover, a similar distance of the south-southeast, the Drevbreen section has 180 m exposed. The top of the formation is marked by a conformable transition from grey carbonate above, belonging to the Gipshuken Fm. The base is unconformable and rests on Early Carboniferous rocks at Reinodden and directly on pre-Devonian basement elsewhere. The formation becomes increasingly conglomeratic towards the south, while north of Bellsund it appears to pass into the carbonates of the Tyrrellfjellet Mbr. The sandstones, which occur throughout, are well sorted, unimodal and fine- to medium-grained, with colours varying from brown to yellow, grey and reddish. They are predominantly quartzose and commonly conglomeratic. Cement is usually calcite or dolomite, occasionally chert. Rock fragments of chert, quartzite and quartz-schist are common. Feldspar is present, but not common, and heavy minerals are rare. The sandstones are thin- to thick-bedded with some cross-stratification. The conglomerates occur as lenses or well-defined thin beds throughout. They are composed of angular and well-rounded quartz, chert and quartzite pebbles which are usually less than 3 cm in diameter. The matrix is generally medium-grained sand. The shales are silty and fairly pale, green to dark grey, and are interbedded with the sandstones, especially in the upper part. The interbedded carbonates are thin to thick-bedded. The limestones are highly fossiliferous, sparry and sandy in the lower part at Drevbreen, though no fossils have been recorded elsewhere. At the top they are micritic, bioturbated, slightly bituminous and contain chert nodules; elsewhere they are of fine texture. Stylolites are common. The dolostones are grey, micritic and sandy, in places silicified and comonly vuggy with silica and dolomitefilled geodes locally. Nysaether (1977) distinguished upper, middle and lower units at Drevbreen on the basis of the type of carbonate present. The topmost 27 m contains only limestone, some of which is slightly bituminous, with chert nodules and a sparse fauna of bivalves and gastropods. The middle unit, 83 m thick, is characterized by dolostones containing corals, limestones being absent. Some of the dolostones are silicified and many are vuggy, with silica and dolomite-filled geodes in the upper part. In the lowermost 70 m exposed, the carbonates are almost exclusively limestone with abundant and varied fossils. Palaeontology and age. Almost the only fossils recorded from this formation are from Drevbreen where corals, brachiopods, crinoids, gastropods, bryozoans and fusulinids have been found in the lower unit (Nysaether 1977). The rich fusulinid fauna is of Late Carboniferous (Gzelian) age except at the top of this unit where there is a possible

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CHAPTER 10

transition to Asselian (Permian) affinities. The middle unit contains only corals, other fossils perhaps having been destroyed by dolomitization, while the upper unit has only a few gastropods and bivalves in the limestones. If the top of the lower unit marks the Carboniferous-Permian boundary, then the higher two units must be earliest Permian. Corals were reported in sands at Ahlstrandodden by a CSE party in 1985. Thus Nysaether's lithocorrelation with the Drevbreen beds is crucial to the dating of the Reinodden Fm. As the Drevbreen beds underlie Gipshuken Fm lithologies at Drevbreen, it seems a logical correlation.

10.3.4

Hyrnefjellet Formation (Treskelen Subgroup, Gipsdalen Group)

Exposed t h r o u g h o u t the H o r n s u n d area, the Hyrnefjellet F o r m a tion (Birkenmajer 1959; Cutbill & Challinor 1965; Siedlecka 1968; B i r k e n m a j e r 1964) is variable in thickness f r o m 30 m to 500 m. It is d o m i n a t e d by r e d - b e d s - m u d s t o n e s , sandstones, c o n g l o m e r a t e s a n d breccias, a l t h o u g h white quartz-rich sandstones and conglomerates b e c o m e increasingly significant t o w a r d s the top. It is also characterized by rapid lateral facies variations. In general there is m o r e c o n g l o m e r a t e in the west and southwest f r o m where the sediment is t h o u g h t to have been derived. The coarser lithologies c o m m o n l y show large-scale cross-stratification, channelization and erosive structures. Clasts include quartzite, limestone, dolostone, schists and red-beds; all are p r o b a b l y derived from a D e v o n i a n source. D e p o s i t i o n o c c u r r e d in a fluvial alluvial fan e n v i r o n m e n t , with channel, overbank, point-bar a n d possibly lacustine deposits present. Evolution o f the basin was controlled by local tectonics, resulting in occasional m a r i n e incursions. N o fauna have been f o u n d in the f o r m a t i o n to date, but it is considered to be of Late C a r b o n i f e r o u s age on the basis of regional correlations. The formation is not widely exposed, seen well at Kopernikusfjellet, and is controlled by Paleogene structures. It consists of 30 m of conglomerates there, 95m at Urnetoppen and about 70m are exposed at Hyrnefjellet. Thicknesses increase rapidly southeastwards to about 270 m at Adriabuka. Gjelberg & Steel (1981) gave a thickness of over 500m. The upper boundary of the formation is an unconformity at the base of the Treskelodden Fm, which separates the predominantly grey deposits of the Treskelodden Fm from the red Hyrnefjellet Fm (Birkenmajer 1984). The formation rests on deeply weathered and eroded shales of the Early Carboniferous Adriabukta Fm on Urnetoppen. It is not known elsewhere. The succession is characterized by repeated upward-coarsening sequences in which texturally immature red clastic sediments (mudstones and sandstones grading up into conglomerates and breccia) are overlain by texturally mature white quartzitic sandstones and thin conglomerates which increase in volume upwards. Three major lithotypes occur, sandstones (60%), conglomerates (30%) and shales (10%), rhythmically interbedded throughout the formation. They show rapid lateral facies variation and become more conglomeratic to the southwest. Red and pink sandstones, fine to coarse-grained and commonly cross-bedded and lenticular, predominate in the section on Hyrnefjellet but are less common to the west, where thicker rudaceous rocks occur. Finer grained rocks are more common to the east and north. The colouration is due to the relative abundance of hematite and ilmenite, which may be partly due to the derivation of these rocks from the ferruginous Devonian deposits. Cementation is commonly siliceousferruginous in the lower part, with the appearance of carbonate and sulphate higher up. Porosity is usually low. In contrast, at the top or base of the sandstone-conglomerate cycles, well-sorted, pale, quartzitic, fine- to medium-grained sandstones occur, showing occasional large-scale crossbedding (wedge, trough-shaped or planar), with white quartz-conglomerate intercalations. The red conglomerates which occur interbedded with the sandstones in the cycles are more predominant in the west. The beds are irregular, commonly lenticular and generally less than 1 m thick. Large-scale crossbedding is a frequent feature and the conglomerates usually fill channels eroded in the siltstones and shales. The conglomerates became finer upwards, passing into sandstones. The topsets of these cross-bedded units are commonly truncated by erosion. The matrix is usually red and arenaceous. Clastics are usually less than 10cm across, but may be up to 3 m. They consist of white or grey rounded quartz and sub-rounded to highly angular red and black sandstones. The clasts consist of white, pink,

grey and yellow quartzites, limestones, dolomites and schists as well as red quartzitic sandstones. The sandstone clasts may be intraformational, or derived from Devonian strata. The other lithologies are almost certainly derived from pre-Devonian rocks. A decrease in sorting and an increase in angularity occurs in a southwesterly direction, with a transition to very poorly sorted, angular breccias. At the base of the formation at Adriabukta and also at Meranpynten to the south, on the strongly weathered top of the Adriabukta Formation, are red medium to coarse breccias/conglomerates with angular to sub-angular fragments of red, yellowish and pink sandstone, 2-60 cm in diameter, and some 1-3 cm diameter rounded quartz pebbles, contained in a similar, but finer matrix. Stratification is absent and the fragments are chaotically arranged, with no imbrication. Horizontally bedded siltstones and shales form a minor constituent of the formation, but become more important to the east. They are red, purple and variegated due to the presence of iron oxides, and in general have the same mineralogy as the sandstones. Clay minerals are almost entirely absent, although muscovite, sericite, biotite and chlorite occur with finely divided quartz. Occasional ripple-marks can be found, some irregular and parallel, others of linguoid form. Casts of irregular large desiccation cracks up to 100cm in diameter occur at the base of the sandstones in places and small cracks are found in the siltstones. Truncated, convolute lamination, associated with fine-grained, laminated sandstones is also present in places. Palaeontology and age. The only recorded fossils are conifer branches found in the highest part of the succession at Treskelen (Birkenmajer 1984). As it is lies beneath the Treskelodden Fm, it may be of Late Carboniferous age. It is possible that it is the lateral equivalent of the lower Reinodden Formation/Drevbreen Beds, which are also cyclic and upward-coarsening. The lower unit of the Drevbreen beds is of Late Carboniferous age (Nysaether 1977). The formation post-dates the Early Carboniferous Adriabukta Fm (Tournaisian/Visean) and the Adriabukta tectonic phase which folded it, so may be Bashkirian to Moscovian in age. Cyclic conglomeratic red-beds are also found interbedded with marine sediments in the Bashkirian Ebbadalen Formation and the Bashkirian-Moscovian Landnordingsvika Fm, which could well be its lateral equivalents in central Spitsbergen and Bjornoya respectively. The Ebbadalen Fm also contains evaporites, which provide another environmental link in view of the sulphatic cement in the higher levels of the Hyrnefjellet Fm. The Moscovian Pyramiden Conglomerates (Minkinfjellet Fm) of central Spitsbergen, which overlie the Ebbadalen Fm are another possible correlative. They also contain conglomeratic red-beds derived from the west, interbedded with evaporites and marine carbonates. Similarly, the Moscovian T~rnkanten Fm of the Isfjorden area has cyclic red beds and marine limestones.

10.3.5

Sergeijevfjellet Formation (Billefjorden Group)

The Sergeijevfjellet F o r m a t i o n (Siedlecki 1960) consists of approximately 180 m of shales with fine-grained sandstones and siltstones. The sandstones are cross-bedded in places, the shales contain a b u n d a n t plant debris, and thin coals are c o m m o n . They were clearly deposited in a fluvial e n v i r o n m e n t with localized flood basins and swamps. T h e r e was no m a r i n e influence. It is of Early C a r b o n i f e r o u s age, p r o b a b l y Serpukhovian, although this is not well-defined. Early Carboniferous deposits in the northern Sorkapp Land-Hornsund area have been known since early investigations (Nathorst 1910; Freebold 1935; Orvin 1940). Siedlecki (1960) originally recognized the Sergeijevfjellet beds as a distinct unit, and they were given formation status by Cutbill & Challinor (1965). This is the youngest formation of the Billefjorden Group in this area. It crops out mainly in northwest Sorkapp Land and has also been recognised further east at Tsjernajafjellet.The formation lies beneath Triassic sandstones in northwest Sorkapp Land, separated by an angular unconformity. Further east, west of Tsjernajafjellet, it appears to be conformably overlain by the Bladegga Conglomerates (?lower Hyrnefjellet Fm: see Gjelberg & Steel 1981). The base of the formation is conformable with the massive sandstones of the Hornsundneset Fm. Siedlecki (1960) described the sequence on Sergeijevfjellet, which may be taken as the type section. The lithology is shaley: lighter grey and yellow to black shales, with intercalation of grey and brown fine-grained sandstone and siltstone. These latter interbeds are generally less than 30 cm thick, except for three major sandstones, 30, 20 and 15 m above the base. Some of the sandstone units are cross-bedded. Plant detritus is found in the shales,

SOUTHWESTERN AND SOUTHERN SPITSBERGEN especially in the upper part of the sequence. A coal seam 0.95-1.0 m thick occurs near the top of the section on Sergeijevfjellet, overlying carbonaceous shale. Additional coals, which are thin and clayey, are found in the black shales at the base of the formation. These shales also contain limonitic concretions. The shales contain plant fragments, including imprints of Stigmaria and stems of Lepidophyta. The formation has yielded abundant miospores (Siedlecki & Turnau, 1964) that indicate an Early Carboniferous age, probably earliest Serpukhovian (though possibly Late Visean-Late Serpukhovian). The assemblages found do not show any clear correlation with those described by Playford (1962, 1963) for the Billefjorden Group of Central Spitsbergen. Turnau suggested that this may be due to the younger age of the Hornsundneset and Sergeijevfjellet Fm.

10.3.6

Hornsundneset Formation (Billefjorden Group)

Originally recognized as a distinct unit by Siedlecki (1960), a n d given f o r m a t i o n status by Cutbill & Challinor (1965) this is the thickest, (750 m) and m o s t coarse-grained unit of the Billefjorden G r o u p in southern Spitsbergen. It is d o m i n a t e d by fine- to m e d i u m grained sandstones, a l t h o u g h granular a n d pebbly sandstones also occur. Clasts are derived f r o m P r e c a m b r i a n basement. Plant remains are c o m m o n a n d thin coal seams are present in places. It was deposited in the Early C a r b o n i f e r o u s (probably late Visean to early Serpukhovian) within an alluvial system, p r o b a b l y by braided streams. There is no evidence of a m a r i n e influence. The Hornsundneset Fm is a sequence of largely arenaceous around 700-750 m thick in the type area of northwest Sorkapp Land. It has been noted in inner Hornsund where it is 500-700 m. The formation lies conformably below the Sergeijevfjellet Formation. The lower boundary is a 60 cm quartzitic conglomerate lying unconformably on pre-Devonian basement in the type area. However, in inner Hornsund it overlies the Adriabukta Formation, apparently conformably (Gjelberg & Steel 1981). Siedlecki & Turnau (1964) and Birkenmajer (1964, 1979) showed the formation to consist predominantly of light grey, light yellow and brown quartzose sandstones, which are generally fine- to medium-grained although grain-size ranges up to 5 ram. They are thick-bedded (0.25-2.0 m), blocky and commonly contain large-scale cross-bedding (10-100 cm sets) which are generally indicative of eastward-flowing currents. The cement is siliceous, clayey or sideritic. Locally, plant impressions are common. Pebble-lag conglomerates occur occasionally at the base of the sandstone units in the lower part of the sequence and at the base, where it lies on pre-Devonian basement. They are slightly imbricated, and pebbles consist of rounded quartz and angular local Precambrian basement fragments. Inter-bedded layers up to 1 m thick of dark-grey, fine-grained sandstone, siltstone and shale occur in places, especially at the base. The dark colouration is due to the presence of carbonised plant remains and there are local coal seams. Plant remains have a widespread occurrence: Stigmaria and Lepidophyta (probably Cordaitales) have been found in the sandstones which indicate an Early Carboniferous age. Miospores have been investigated (Siedlecki & Turnau 1964) and, although not abundant, also indicate an Early Carboniferous age, probably earliest Serpukhovian, although possibly Late Visean.

10.3.7

Adriabukta Formation (Billefjorden Group)

U n c o n f o r m a b l y overlying D e v o n i a n basement, the A d r i a b u k t a F o r m a t i o n (Birkenmajer & T u r n a u 1962; Cutbill & Challinor 1965) consists of black, d a r k grey a n d green 'unfossiliferous' shales. Some thin sandstone interbeds and c o n g l o m e r a t e lenses are present. The unit was deposited in a shallow near-shore m a r i n e e n v i r o n m e n t , in a basin that b e c a m e increasingly restricted and possibly a n a e r o b i c later in the deposition of the formation. Plant imprints are quite c o m m o n and a p o o r l y preserved bivalve f a u n a has been found. As in the overlying two formations, the age is poorly defined but is p r o b a b l y T o u r n a i s i a n to Early Visean. The Adriabukta Fm crops out in the inner Hornsund area and Sorkapp Land, south of Treskelodden. It is absent in northwest Sorkapp Land,

187

where the Hornsundneset Fm lies directly on basement. This incompetent formation suffered severe deformation as a thrust horizon during the Paleogene West Spitsbergen Orogeny. Thicknesses are thus difficult to measure, but at least 500 m are present in central Sorkapp Land, thinning to about 300m in Adriabukta. The formation appears to lie conformably beneath the Hornsundneset Fm on Hyrnefjellet and in Sorkapp Land, but mid-Carboniferous uplift has, however, caused erosion of the top of the formation in places, where it is overlain by Triassic strata and the Hyrnefjellet Fro. It has a basal angular unconformity (of 10-20 ~ on both Devonian and pre-Devonian basement. The formation, which is about 300 m thick in the type section, consists predominantly of black, dark-grey and dark-green unfossiliferous shales. Thin arenaceous intercalations are quite common, these are generally poorly sorted, fine-grained sandstones which are usually less than 15 cm, but may be up to 50 cm thick. Graded bedding has been observed in some of these sands. Conglomerate lenses and layers, up to 2 m thick, also occur in the lower half of the sequence. They consist of angular and sub-angular quartz pebbles 0.5-5.0cm in diameter, contained in a sandy matrix. North of Adriabukta, there are basal conglomerates 2-3 m thick, lying unconformably on Devonian sandstones. The bottom 25m of the formation at Adriabukta is more arenaceous. It consists of grey, fine-, medium- or coarsegrained sandstones in beds 2-50cm thick, alternating with subordinate black arenaceous shales and conglomerates. The sandstones show crossbedding and the bottom of some beds contain groove- and prod-casts. A poorly preserved assemblage of unidentifiable concentrically-ribbed bivalves was reported by Birkenmajer (1964) from the basal arenaceous beds on Marietoppen (north of Adriabukta). The basal beds also contain frequent plant imprints, generally Lepidophyta, including Stigmaria 2-3 cm wide and up to 50 cm in length (Birkenmajer & Turnau 1962). Miospores (Birkenmajer & Turnau 1962) indicate an Early Carboniferous age. The occurrence of Velosporites echinatus in one of the lowermost samples (Sample A1) may indicate a Tournaisian age for this assemblage while Turnau stated that the presence of Densosporites cf. granulosus Kosanke in the lower sample (Sample A2) suggested a Visean age. However, a Tournaisian/Early Visean age for the lower samples (A1 & A2) is quite consistent with other palynological data. The sample taken from higher up in the shale sequence (Sample A3), yielded a much wider variety of miospores which indicate an Early Visean age.

10.4

Devonian strata

D e v o n i a n strata, so well developed in n o r t h e r n Spitsbergen (Chapter 8), a p p e a r n o r t h of H o r n s u n d a n d south in S o r k a p p L a n d as one f o r m a t i o n . The n o r t h e r n o u t c r o p has been described by B i r k e n m a j e r (1964) a n d the s o u t h e r n by D a l l m a n n et al. (C13G, 1993). B i r k e n m a j e r noted early historical events with the discovery o f the o u t c r o p by de Geer in 1899 a n d soon confirmed as D e v o n i a n (1910) a n d reported by N a t h o r s t (1910). T h e y were m o r e fully described by H o e l (1922, 1929) a n d included in the general a c c o u n t by Orvin (1940). Monaspis fragments (Heintz 1929) a n d ostracodes (Solle 1935) m a t c h e d the W o o d Bay F o r m a t i o n in the north. Orvin t h o u g h t that bivalves resembled G r e y H o e k F o r m a t i o n forms a n d suggested that the lower 150 m of red beds, limestones and c o n g l o m e r a t e s m i g h t correlate with W o o d Bay and the u p p e r d a r k 200 m unit with Grey H o e k strata, both m i d d l e D e v o n i a n . Sandstones and shales were taken as G r e y H o e k . Orvin postulated a substantial D e v o n i a n thickness south of the m a i n basin, to the north. T h e r e m a y have been a further 650 m as estimated, by B i r k e n m a j e r a n d possibly of W i j d e f j o r d e n F o r m a t i o n age with d a r k grey a n d black clastics.

Marietoppen Fm. Birkenmajer (1964) introduced the name Marietoppen for these rocks now referred to as a formation and described it as follows. Upper Mbr, 150-200m of green, grey-green or black shales cleaved and slightly phyllitized. Undetermined bivalves were collected (F6yn & Heintz 1943). Fish were found in 1960 (tuberculated arthrodire bones, Porolepis plates, holoptychiid scales and crossopterygian teeth). Only the lower part of the Grey Hoek Formation may be represented here. This is suggested by the bivalve ?Myalina formed in the Forkdalen Member of the Grey Hoek Fm. Murashov & Mokin (1979) correlated it with the Wijde Bay Fm.

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Middle Mbr, 550m of alternating green and red, often variegated arenaceous shales in layers 0.1-1 m intercalated with thin, yellow and pink, silty limestones of which the three uppermost yielded indeterminate ostracods, fish plates and teeth. There are no outcrops of this member north of Marietoppen but south of Hornsund the member probably occurs. Various (some problematic) finds of fossils led Birkenmajer to conclude that the member correlates with the Wood Bay Formation. Murashov & Mokin (1979) suggested Grey Hoek Fm age. Plant remains suggested Givetian age. Lower Mbr, 300-350 m of typically red (hematite) fine-grained sandstones, siltstones and arenaceous shales as well as calcareous sandstones and arenaceous limestones, the latter two facies are often nodular. There are also some variegated sandstones and quartzite with current bedding. Sedimentary breccias occur and may contain Porolepis type fragments. Fossil fish in the lower part of this Middle Division may correlate with the upper Wood Bay (i.e. Stjordalen Division). This is the most reliable biostratigraphic age estimate. At the base is a quartz conglomerate or sedimentary breccia with fragments of limestones and cherts from the underlying strata beneath an unconformity surface. Correlation of this unit is most likely with the Wood Bay Formation except that the Lower Wood Bay strata are not represented here. Birkenmajer (1964) gave detailed sections and profiles of this member in different localities. The later publication (Dallmann et al. 1993) concerns the outcrops in narrow strips on both sides of Samarinbreen south of Hornsund. The structure here is probably synclinal, the axis being occupied by the glacier and appears to have formed in Late Devonian or Early Carboniferous t i m e - probably Late Devonian Svalbardian diastrophism. Beyond this syncline erosion has removed Devonian strata. South of Hornsund the thickness of the Marietoppen Fm is about 800 m with possibly more beneath the glacier, compared with 1000m to the north. The lower contact is a distinct angular unconformity on metamorphic basement often with a weathered horizon and local basal polymict conglomerate or breccia with boulders up to 1 m.

With its descriptive text it addressed this problem thoroughly with extensive structural observations (Hjelle, Lauritzen, Salvigsen & Winsnes 1986). In the meantime Russian geologists had made general and geochemical observations (Turchenko et al. 1983). Hjelle had already noted the similarity between the metabasites and those of Chamberlindalen in north Wedel Jarlsberg Land and Turchenko extended this comparison with the basites in southwest Wedel Jarlsberg Land. Krasil'shchikov & Kovaleva (1979) made a different and comprehensive scheme for the whole of the west c o a s t depending heavily on the Polish work, extending it from the south. Barkhatov (1985) argued for a Vendian Complex with tillite and an older complex, but not mapped. The main difference between the above and a later interpretation (Harland, Hambrey & Waddams 1993) is that whereas the earlier authors agree that the tilloids at Kapp Linn6 in the north are Varanger glacial deposits (being rich in granitoid stones), Harland e t al. identified them with the Later Varanger glacial epoch. They correlated the diamictites and conglomerates in the south of Nordenski61dkysten with the earlier Varanger tillite horizon partly because they lack granitoids and are closely associated with basites. It was then postulated that most of the other rock units were found between the two tillite horizons and therefore that almost the whole outcrop of older rocks is of Early Vendian, i.e. Varanger age. As stated by Harland e t al. confidence in their interpretation here is less than that either north of Isfjorden or south of Bellsund. It is to a large extent influenced by comparison with these adjacent areas. Nevertheless this hypothesis was applied to describe the succession, while commenting on alternatives. The interpretation entails one major thrust fault from eastern Van Muydenbukta northwest and out to the sea north of Orustosen. This displaces the successions on either side and makes a feasible succession from the map.

10.5

10.5.1

Proterozoic strata of western Nordenski61d Land

Western Nordenski61d Land (west of Gronfjorden) boasts the classic Festningen section along the Isfjorden coast where Paleogene down to early Carboniferous strata are displayed in a sequence younging eastwards. The Orustdalen Formation rests with steep angular unconformity on the older rocks, which occupy a wide strandflat west of the mountains along which this unconformity is exposed south to Bellsund. To the west of this line, this strandflat, rarely exceeding 50 m in height above sea level, is named Nordenski61dkysten and is entirely occupied by Proterozoic rocks, save for at least two infaulted outliers of Carboniferous rocks. This line marks the western edge of the Central Basin. A convenient limit to our study area for this section is Gronfjorden to the north and Fridtjovbreen draining down into Fridtjovhamna in the south. This is approximately along the line of strike of the rocks which, continuing southwards across Van Mijenfjorden, include the remarkably linear Akseloya in our area and the western tip of Nathorst Land further south. So the area is neatly divided by the N - S unconformity into the Precambrian outcrop of Nordenski61dkysten, with the tip of Nathorst Land in the west and the obvious foldbelt with Carboniferous through Cretaceous rocks occupying the mountain front. Following the primary survey by Nathorst (1910), the principal investigations of this area have been carried out by Norsk Polarinstitutt geologists resulting in the following publications. Orvin's (1940) outline of Spitsbergen Geology paid particular attention to the western foldbelt and the basites which characterise the older rocks in the western coast. A planned series of investigations led to the definitive description of younger rocks at the Festningen section (Hoel & Orvin 1937). A general idea of the presence of tilloids and conglomerate at Kapp Linn6 and in the south at Kapp Martin was familiar. However, the first systematic survey of the whole of Nordenski61dkysten was by (Hjelle 1962, 1969) who took into account earlier Norwegian work. This work was later consolidated in the 1 : 100 000 geological maps with descriptions and, in particular, sheet B10G.

Sequence of the rock units

Kapp Linn6 Fm, 1+ km. Hjelle (1962) named the northern diamictite the 'Kapp Linn6 Tillite Series'. The top of the formation is not preserved being synclinal. The rock is stone-rich in an orange to grey-weathering psammitic schist, with thin greenish grey-weathering schist and sandy dolostone interbeds. Alternation with thicker more quartzitic layers up to 15 mm thick gives a visible banding. The stones are mainly quartzites, dolostones and granites. The base of the formation is at B~todden (B~todden member). Linn6fjella fro/unit, 1.2+ km. The outcrop in fig. 37 of Harland et al. (1993) is taken from Hjelle et al., B10G, (1986) and numbered '5?' and '3-4'. Hjelle (1962) proposed the name Linn~fjella for this thick conformable sequence of phyllite and quartzite with limestone beds. Malmberget unit/fm. Below the Linn&jella strata the map (B10G) shows three numbered units (3) limestone marble as at Malmberget; (2) phyllite; (1) quartzite as at Jainbreen. Hjelle et al. regarded this succession as comprising the lowest units in the area because they equated diamictites and conglomerates both north and south of the strandflat. For this unit the name: Malmberget fm with the three members 1 2 and 3 is tentatively suggested. L~gnesbukta Gp. Four formations are grouped here (Harland, Hambrey & Waddams 1993) and altogether are correlated with the Earlier Varanger glacial episode. L~gneset Fro. This is the Lfigneset tillite of Hjelle (1962, 1969) and is unit 10 of Hjelle et al. (1986). It is included in the Vendian tillite conglomerates of Turchenko et al. (1983) - their unit 8. It is well displayed at six localities other than L~gneset and includes the diamict formation at Slettneset and at Millarodden. At Lfigneset two N-S bands 70-90 m thick are separated by 100-125m of calcareous phyllite, white marble, oolitic limestone and pale green chloritic schistose diamictite. The two bands cropping out may be repeated by folding or faulting. The stones are mostly dolostone, quartzite and limestone with diameters typically 20-100 ram. Sedimentation was probably by ice rafting into a shallow carbonate sea with clastic and basic tuff input. The diamictite at Millarodden is correlated with this unit.

SOUTHWESTERN AND SOUTHERN SPITSBERGEN Diabaspynten is dominated by dark green amphibolite, probably lava flows and related tufts. They were noted by Orvin (1940) as gabbros along the west coast. Gravsjoen unit/division. This unit of varied facies is dominantly phyllites with metavolcanics and quartzites associated with massive basites. Thinner beds of dolostone and limestone are also present. Hjelle et al. mapped these rocks as units, 7, 6 and 9. From their map the unit would underlie the L~tgneset Formation. L~gnesrabbane Fro, 1-2 km. Following Hjelle (1969), his LSgnesrabbane calcareous beds are placed above the Kapp Martin conglomerates. The formation comprises two members. Upper (limestone) Mbr (light grey, laminated, partly oolitic interbedded with calc phyllite, black phyllite, white crystalline marble and minor conglomerates. Lower (dolostone) Mbr, 600 m, is a thick stone-free dolostone 600 m thick forming the rocky headlands west of Kapp Martin. Kapp Martin Fro, 800 m. This formation is dominated by massive polymict conglomerate occurring in beds 0.05-4 m thick in an assemblage of phyllites coarsely crystalline black limestone and subsidiary quartzite and dolostone. Waddams (1983) suggested deposition from sediment flows from material released by ice on an unstable slope.

10.5.2

Mineralization

Mineral occurrences, mainly of sulphides, invited mining that proved uneconomic. They occur by the coast at the northern and southern limits of the area. The rocks in between may also repay further investigation (Hjelle 1962). In the north at Kapp Mineral 2.5 km east of Isfjordradio Flood (1969) reported on the early workings where galena and some sphalerite occur in intensively brecciated rock in a zone a few metres wide near a fault zone. Further investigation showed the presence also of pyrite and chalcopyrite. However, continuation at depth was disproved. In the south 3 km west of the mining camp at Millarodden is a small island, Sinkholmen, which may be the richest exposed mineral deposit in Svalbard where 240 tons were mined mainly of sphalerite. Sulphides occurring in the breccia are sphalerite, galena and pyrite and in the associated calcite mass Flood (1969) recorded sphalerite, pyrite, chalcopyrite, bornite, idaite, chalcocite, neodigenite and covellite. Tetrahedrite occurred in both hosts; the gangue was fluorite and quartz in the breccia. The occurrences according to the above stratigraphy would be hosted in Late Varanger carbonates in the north and early Varanger in the south. Detailed stratigraphy was not recorded.

10.6

Proterozoic strata of western Nathorst Land and northwestern Wedel Jarlsberg Land

Observations in 1838 and 1839 were made from the ship L a R e c h e r c h e when interest was shown in mineral and coal occurrences. (Nissan 1941). Garwood & Gregory (1898), on Conway's expedition, first noted an ancient boulder bed thought to be equivalent to Reusch's Moraine in N o r t h Norway (Varangerhalvoya). The general outcrop pattern was established by Orvin (1940). This was supplemented by further mapping of the younger rocks by the Polish group about 1938 (Rozycki 1959). Much of the area of older rocks was surveyed systematically by the Wisconsin group led by Craddock (Kowallis & Craddock 1984; Craddock et al. 1985; Bjornerud 1990, 1992). All these observations were compiled in the 1:100 000 map sheet ( B l l G ) with the accompanying memoir (Dallmann et al. 1990). CSE stratigraphic traverses enabled the above results to be related to those from other areas in Svalbard (with respect to the older rocks) (Harland 1978; Hambrey & Waddams 1981; Waddams 1983; Harland, Hambrey & Waddams 1993). The main feature of the area is a northward-plunging open syncline which concentrates the youngest rocks at the north in the Kapp Lyell area. Older rocks then occur successively in a V outcrop

189

pattern. The variety of facies is such that correlation between one limb and the other is not at first obvious, but is confirmed by continuous mapping round the southern corner of the V. Thus even within this small area a duel nomenclature developed between the east and the west limbs (e.g. Dallmann et al. 1990; Bjornerud 1990; Harland et al. 1993). As in Oscar II Land, formations were assigned to two groups by Harland, Hambrey & Waddams (1993) for the rocks which were interpreted as Vendian and which overlie unconformably an older basement. There is general agreement on the mapping of sheet B 11G (Van Keulenfjorden). It is a key area in interpreting and correlating the strata to the north and south of the sheet. This general problem is reserved for discussion in Section 10.9 below.

10.6.1

Neoproterozoic succession of northwestern Wedel Jarlsberg Land

The following succession is based on early CSE work (Harland 1978; Hambrey & Waddams 1981; Waddams 1983), on University of Wisconsin work (Kowallis & Craddock 1984; Craddock et al. 1985) synthesized by Norsk Polarinstitutt mapping (e.g. Hjelle 1969; Dallmann et al. 1990, B l l G ) and followed with some reinterpretation by Harland, Hambrey & Waddams (1993) which forms the basis of the succession below and recounts how it came about (Fig. 10.4).

Kapp Lyeil Gp. This group comprises map units 27-31 of Dallmann et al. and three formations with ten members as listed below.

Lyellstranda Fm, 1.3kin. This formation was first described with two divisions by Waddams (1983b), the upper division (Lyellstranda) and the lower (Kolvebekken). He described the upper division, 3.0 km, as graded polymict conglomerate and buff-weathering dolomite psammite with occasional slate and calcareous phyllite containing dispersed dolostone and quartzite boulders up to 1.6m. He mapped six units by stone content and described the lower unit, 0.7 kin, as grey laminated quartzite and psammite with rare beds of conglomerate and occupying the coastal plain north of Longnedalen. It was not identified on the eastern limb of the syncline. However, the work by Craddock and colleagues was more detailed and their divisions are followed here with five members (unnamed). Mbr 5, Upper dolostone clast unit Mbr 4, Upper no dominant clast unit Mbr 3, Middle dolostone clast unit Mbr 2, Upper quartzite clast unit Mbr 1, Lower no dominant clast unit. Harland et al. (1993) concluded that the Lyellstranda Fm was influenced by a variety of glacially related processes. Good indications are dropstones in the psammitic diamictites formed by ice-rafting in a proximal glacio-marine environment. More distal glacio-marine conditions give phyllites with dispersed stones. The conglomerates are of similar material to the diamictites and probably formed from reworking of glacial deposits by gravity-driven sediment flows, as postulated from the older Kapp Martin Conglomerates (Waddams 1983b). Loading of the underlying bed is also evident. Logna Fro, c. 200 m. This is a soft, finely laminated dark grey phyllite with isoclinal folds parallel to the bedding. Dundrabeisen Fro, c. 1.4 km. This variable formation consists of alternating beds of psammite and phyllite, often with dispersed stones, conglomerate, and stone-rich diamictite. The stones (up to 1 m diameter) are mainly dolostone and quartzite with a minority of limestones and granites. Genesis was similar to the Lyellstranda Fm but reworking of till by subaqueous flows was less significant. Four members are listed following Craddock et al. as above. Mbr 4, Limestone clast unit Mbr 3, Lower dolostone clast unit Mbr 2, Lower quartzite clast unit Mbr 1, clast-poor unit Konglomeraffjellet Gp. This group was defined by four main formations in the east (Harland, Hambrey & Waddams 1993) following Hjelle (1969), Harland (1978) and Waddams (1983), and additional basal formation in the west above the unconformity. Different nomenclature has been applied to coeval rock units in east and west limbs of the syncline.

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CHAPTER 10

Fig. 10.4. Vendian geology of northwest Wedel Jarlsberg Land (redrawn from Harland et al. 1993).

Vestervfigen Fro, c. 340m in the east. Massive grey quarzites are interbedded with quartzitic slate and soft phyllite. It is equivalent to HjeUe's (1969) Konglomeratfjellet shale and quartzite beds. It is recorded only in the east and is similar to the rocks above, except for the absence of stones. Chamberlindalen Fm, about 1-2 km, in the east was described from the eastern outcrop (Harland 1978) where the succession is thicker, more varied and better exposed, but tectonically divided by thrust faults. The outcrops occupy the two broad valleys Chamberlindalen in the east and Dunderdalen in the west. Upper mbr, exposed southwest of Vestervfigen, is of grey slate with calcareous concretions, thin amygdaloidat lava flows and calcareous pyroclastic rocks. Middle mbr comprises well-bedded grey limestone, with dolostone clasts, above cream weathering dolostone, grey oolitic limestone and dark amygdaloidal basalt. Interbedded phyllites are not so well exposed. (Lower) Asbestodden Mbr is of basic lavas (some pillow tavas), pyroclastics and small intrusions interbedded with pelites and carbonates. At Asbestodden the basites have been altered to an asbestos-beating assemblage. Turchenko et aL (1983) described the igneous rocks as porphyritic picrites, both porphyritic and amygdaloidal basalts, andesites with myrmekites (up to 25% quartz), ophitic porphyritic gabbro-dolerites and volcanogenic sediments (e.g. green phyllites). All belong chemically to a single tholeiitic basalt-trachy-andesitic series.

Dunderdalen Fin, 1.9 kin, map unit 35 of Dallmann et al., is the western facies of the Chamberlindalen Fm. The outcrop was mapped by Orvin (1940) as a thick succession of pelite with discontinuous quartzites. Flood et al. (1978) and Harland (1978) suspected a pelitic schist and phyllite up to 1 km thick, and Bjornerud (t990) named it. Within a dominantly pelitic unit, quartzite and carbonate units, sometimes brecciated, often isolated, were interpreted as olistoliths. Whereas exposure is limited in the north, easy access is afforded from Storvika through Orvindalen or Tunsfjodalen in the south of the west limb of the syncline where way-up and relation to underlying strata is well confirmed. Sollwgda Fro, 300+ m in the east. Cliffs of carbonate units are conspicuous in the hills to the east of Chamberlindalen and with many, but minor, tectonic complications, lie beneath the Chamberlindalen Formation. Three members are easily distinguishable at a distance by colour; Upper mbr mainly bedded grey limestone and dolostone, Middle mbr yellow-weathering dolomitic marble and black bituminous limestone. Lower mbr pale yellow-weathering dolomite marbles with dark volcanics and silts. Slettfjelld~den Fin, 50-100 m. In the west this was referred to informally by Bjornerud (pers. comm.) as the Slettfjelldaten F m of dolostones and limestones with sedimentary breccias, digitate stromatolites and chert beds.

SOUTHWESTERN AND SOUTHERN SPITSBERGEN In the south, (at the head of Chamberlindalen) on the flanks of Konglomeratfjellet a substantial thickness of dolostone breccia/conglomerate with clasts up to 0.5 m long occurs at the base of the formation. In the southwest Hambrey estimated 285 m (ofCSE informal Orvindalen formation) suggesting offshore distal turbidites (phyllites) to shallow marine tidal facies, with oolitic and channeled stromatolitic dolostones. The dolostone diamictite could be a shallow marine deposit with some ice rafting. Fluykalven Fin (in the west). At Floykalven, south of Dunderbukta, is a diamictite rich in quartzite and carbonate stones the latter with occasional oncolites and stromatolites typical of the lower tillite facies already described north of Bellsund and Isfjorden. Bjornerud divided her equivalent Konglomeratfjellet Fm into two divisions: upper green-coloured, 500 m and lower brown-coloured, 400 m. East of Storvika in the south, two divisions were observed by CSE in 1983. Upper division, 330 m, dark grey phyllite with dispersed stones (dolostones, quartzite and vein quartz up to 0.35 m long, but no granitoids), which may be concentrated locally in a matrix of silty carbonate with chlorite in the foliation. Lower division (160m) light brown-weathering dolostone with dispersed clasts locally concentrated to a dolostone-quartzite conglomerate. In many respects this formation resembles the Trondheimfjetla Fm of Oscar II Land. Gaimardtuppen Fm (in the east). This name is applied to the lower of the three divisions which Hjelle (1969) included in his Konglomeratfjellet unit. Two members are distinguished after Harland et al. (1993). Upper mbr (= Gaimardtoppen division of Harland 1978) and phyllite limestone of the Wisconsin group (about 0.5km) is a dark calcareous sequence of psammites and pelites with dispersed stones; some facies are pebbly. A distal turbidite with dropstones is suggested. Lower mbr is the Konglomeratfjellet conglomerate beds of Hjelle (1969), Foldnutane division of Harland 1978, and Conglomeratfjellet Fm of Bjornerud (pers. comm.). Bjornerud (1990) noted that about 5% of the stones are granitic or gneissic and suggested that they could be derived from the Magnethogda sequence a few km to the east. ThiLq'jdlet Fro, 0-50m. This is a black, pyritic, phyllitic limestone (50-100m), with isolated beds of quartz pebble conglomerate. Below is the basal gritstone conglomerate 0-50m with dolomitic matrix resting on the unconformity seen only in the west (Bjornerud 1990). This unconformity is the base of the above which Harland, Hambrey & Waddams (1993) interpreted as the Varanger (Early Vendian) succession in the area with a total thickness of about 6 km.

10.6.2

Proterozoic basement

A m a j o r u n c o n f o r m i t y was m a p p e d in the west by the Wisconsin G r o u p ( B j o r n e r u d 1991) with little overlap b u t m a r k e d overstep, the underlying rocks h a v i n g suffered a m a j o r phase o f d e f o r m a t i o n before V e n d i a n time. I n the east where such an u n c o n f o r m i t y m i g h t also be expected the rocks are obscured by the wide R e c h e r c h e b teen a n d R e c h e r c h e f j o r d e n .

Nordlmkta Group (Proterozoic basement) in the west (Fig. 10.4). A sequence of eight formations was described by Bjornerud in her unpublished map, of which CSE observed the two lower formations in 1983 referred to as the Storvika formation. Not mapping the area CSE did not identify the unconformity in the two traverses made. The whole sequence mapped, and totalling 3.3 km consists largely of dolomitic marbles, phyUites and quartzites not much different from the overlying rocks, but with a distinctive structure. The succession below follows Bjornerud as printed by Harland et al. (1993, p. 102). (8) Dordalen Fro, 150m of heterogeneous dolostone and phyllite. (7) Thiisdalen Fro, 200 m of red brown phyllite and quartzite. (6) Trinutane Fm Ferroan doiostone and pink marble members, 150 m Resinous phyllite member, 30 m Pink cross-bedded quartzite member, 200m (5) SeljehaugfjeHet Fm Grey dolostone member, 150 m Black limestone member, 50 m (4) Botnedalen Fro, 300 m of platy limestone, dolostone and phyllite. (3) Peder Kokkfjeilet Fro, 600 m of sandy dolostone. (2) Evafjellet Fro, ?1 kin, of quartzite and phyllite. (1) Kapp Berg Fm, ?1 km, of phyllite and quartzite.

191

Magnethugda Group (the sequence to the east). East of Recherchebreen and Recherchefjorden is a sequence first referred to by the above name (Harland 1978) (Fig. 10.4). From Bjornerud's ms map and earlier work it seemed possible to correlate these rocks with the Nordbukta sequence so connecting the basal Vendian unconformity in the eastern limb of the syncline. Harland (1978) had noted also a possible similarity between the feldspathic rocks of Magnethogda and those gneissic bodies in the SkSlfjeUet Formation. However, further observations of critical localities in 1992 in the south from Isbjornhamna, Vimsodden, east of Recherchefjorden at MartinfjeUa and Berzeliustinden, supported the view that the Magnethogda does not easily correlate with any other sequence and that most likely the boundary between the central and western terranes of Harland & Wright (1979) passes through Recherchefjorden and Recherchebreen. The account of Dallmann et aL (1990) also implied doubt as to the Nordbukta correlation. Whereas the massive dolomitic marble (map unit 50 of Dallmann et al.) is extensive and might conceivably match one or more of the dolostones in the Nordbukta sequence, there is no match to the feldspathic rocks (map unit 49 augen gneiss and feldspathic quartzite). These rocks amongst so many dolostones, phyllite and quartzite are conspicuously pink. The outcrop area of map unit 49 beside Recherchefjorden is somewhat exaggerated: there is very little feldspathite along the foothills beside the fjord, it is mostly dolomitic marble. However, in the foothills of Berzeliustinden massive gneisses occur without interbeds of non-feldspathic facies though the facies do vary from feldspathic psammitic schists to augen schists and even coarse granitic gneisses. The rocks are intensely foliated and lineated. Rare specimens along the side of Recherchefjorden are almost mylonitic. No associated basic rocks were seen. Thus, the minor feldspathic development in the dominantly basic Sk~dfjellet Fm further south bears no comparison with the Magnethogda rock. Indeed no similar facies have been recorded in the south of Spitsbergen or in the West Spitsbergen Orogen. It is concluded that these feldspathic rocks, with their associated marbles, quartzites, phyllites and schists may belong to a different, once distant, terrane. The Van Keulenfjorden sheet B11G (Dallmann et al. 1990) maps a close association of units 49 (feldspathic rocks) and 50 (massive dolostone). Outcrops of Unit 49 extend about 7 km on each side of Antoniabreen and Unit 50 crops out intermittently for 20 km to the south. In the southern part of the sheet it is associated with units 51 to 55 described as carbonates, phyllites and quartzites. However, the adjoining preliminary sheet to the south, B12G (Ohta & Dallmann 1992), with slight overlap, maps the phyUites as G~shamna Formation and associated carbonates units 50 & 51 (to 14 N) as Hrferpynten Formation. The authors admit that their research is unfinished. It would also be affected by alternative interpretations of the succession to the south (as discussed below in Section 10.9)

Westernmost Nathorst Land. T h e small o u t c r o p of marbles a n d quartzites on the p r o m o n t o r y of M i d t e r h u k e n belong to the M a g n e t h o g d a sequence (as also m a p p e d by D a l l m a n n e t al. 1990)

10.7

Early Paleozoic and Proterozoic strata of southwestern Wedel Jarlsberg Land

This area lies south o f Torellbreen a n d n o r t h of H o r n s u n d a n d east as far as H a n s b r e e n , penetrating the s o u t h e r n part of the Central Basin. F o r descriptive convenience it is distinguished f r o m the area just treated (Section 10.6) because f r o m the Polish base at I s b j o r n h a m n a it has been intensively investigated by Polish geologists since that base was o p e n e d a b o u t 1957 as a c o n t r i b u t i o n to the I n t e r n a t i o n a l G e o p h y s i c a l Year. The base facilitated research in m a n y disciplines, especially Q u a t e r n a r y , and latterly seismic. F o r the p u r p o s e here, the bed-rock geology was comprehensively surveyed u n d e r the leadership o f K. B i r k e n m a j e r and published d u r i n g the years 1958 to 1994. W h a t e v e r was d o n e before has been superseded by Birkenmajer's t e a m so that their accounts f o r m the basis o f this section. M a n y others have visited the area, not least the I n t e r n a t i o n a l Geological Congress excursion in 1960. The Cambridge g r o u p f r o m visits on several occasions was able to f o r m i n d e p e n d e n t opinions on some questions which a p p e a r e d to be controversial. Latterly the N o r s k Polarinstitutt has c o l l a b o r a t e d in m a p p i n g the area: 1:100 000 sheet B12G (Ohta & D a l l m a n n 1992).

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Birkenmajer consolidated the results of the Polish Group north of Hornsund with those of the Norsk Polarinstitutt south of the fjord in a unified stratigraphic scheme developed over the years but essentially the same as that issued to the International Congress in 1960. This scheme in its latest available version is listed below but only down to formation rank. It has the advantage of a single tidy scheme for a large and complex area to which most maps have been related and it has been largely followed by Russian and Norwegian groups (e.g. Krasil'shchikov & Kovaleva 1979, Sheet C13G; Dallmann et al. 1993). The scheme has, however, been challenged (e.g. Harland 1978; Harland, Hambrey & Waddams 1993) on the grounds that stratigraphic units north and south of Hornsund and given the same name, do not necessarily correlate and that a major N-S terrane boundary along Hansbreen and west of H6ferpynten would mean that correlation east and west of that line is also suspect. The assumption that distant units correlate and so receive the same name leads to definitions that may not serve discussion well and possible reappraisal. It may be safer to introduce additional names and eliminate them if and when identity is established. A second cause for discrepancy between Birkenmajer's scheme and that adopted here is that formations are the primary rock units and their combination into groups may reflect different opinions as to their relationships whereas Birkenmajer defined groups and divided them into formations. Birkenmajer's scheme has priority and will be described first. However, the possibly different terranes will be described separately so as to enable discussion of correlation in Section 10.9. Birkenmajer's correlation of his units with those of Ny Friesland and Nordaustlandet are also in question because he assumed a relatively fixistic palinspastic relationship. Birkenmajer throughout indicated that the main groups were separated by diastrophic events which are inserted in the following table in upper case lettering.

*Brattegga (amphibolite) Fm, 300-500m *Angellfjellet (amphibolite) Fm, 0-200 m *Gangpasset (migmatite) Fm, 0-100 m *Torbjornsenfjellet (amphibolite) Fm, 350-600m Steinvikskardet Fm, 100-250 m Gulliksenfjellet (quartzites) Fm, 500-850 m Isbjornhamna Gp Revdalen Fro, 250-350m Ariekammen Fm, 500-1500 m Skoddefjellet Fro, 1000+ m These older rocks, listed above, generally have been referred to as Hecla Hoek. However, on the basis of not assuming correlation until it has been satisfactorily demonstrated this name is avoided here preferring the more descriptive 'pre-Devonian' or 'basement' attribute. Moreover, around eastern Hornsund overlying Devonian strata have been mapped and dated palaeontologically. The successions are described below, west and then east of Hansbreen.

Stratigraphic scheme from Birkenmajer 1978 and 1992

Duneyane Fro, 750m. A dolomitic rock forms much of Dunoyane. It is of light dolostones interbedded with dolomitic oolites and pisolites with Collenia. A t Storoya off Dunoyane it appears to pass upwards into black quartzite and quartzite schist. It has been correlated with Winsnes' Oolitic Limestone Member of the H6ferpynten Formation south of Hornsund which Birkenmajer named as the Dunoyane Member. There it is only 40m thick and was also correlated with the 25m north of Hornsund at Fannytoppen. A distinct name is preferred so as not at first to assume identity. According to Birkenmajer this would be the youngest formation in the Vimsodden-Isbjornhamna terrane, younger than the SlyngfjeUet Conglomerate. It is an isolated island outcrop with no direct evidence as to its relationship with the other rocks of our terrane. The nearest mainland rocks belong to the Vimsodden Subgroup. Projection of local dips suggest that it may be older than the Vimsodden Subgroup. Both formations have similarities with the Akademikerbreen Group of Ny Friesland and have been so correlated. If this be correct the Dunoyane Formation would be pre-Vendian and Late Sturtian or Riphean. Slyngfjellet (conglomerate) Fro. This distinctive formation is the uppermost in the succession both in Birkenmajer's description and his map. The fullest descriptions were given by Birkenmajer (1990, 1991, 1992). At the type locality, Slyngfjellet, the formation may be 500m in this area and divides into two informal members. Upper mbr. Green meta-conglomerate with subordinate sandstone with siltstone and shale intercalations of yellow/brown conglomerate. The unit at the type locality is a green meta-conglomerate with 70 to 80% light green/ yellow lenticular or tabular sharp-edged, sometimes subrounded, homogeneous or laminated quartzite clasts 1-30 cm in diameter; some quartzite slabs <50• 50x 10cm, dolostone slabs 10 to 20cm• and 'red shale' 5-10 cm diameter. The whole is supported by 20-30% green chloriterich schistose matrix. Passing northwards the stones are less tectonized being typically subrounded and in a matrix, often black slate rather than chlorite schist. WBH notes that this facies compares closely with the Gaimardtoppen Fm further north. Lower mbr. Yellow/brown meta-conglomerate. Jens Erikfjellet contains an apparently conformable bed within the Jens Erikfjellet Fm (below the Deilegga Group) which Birkenmajer listed as representing the lower

NY FRIESLAND OROGENY (of Harland 1959) Hornsund Supergp (two groups) Sorkapp Land Gp (Ordovician) Hornsundtind (limestone) Fm Tsjebysjovfjellet (limestone) Mbr, 400 m Rasstupet (limestone) Mbr, 80 m Nigerbreen (limestone) Fm, 120 m Dusken (limestone) Fm, 100 m Luciapynten (dolostone) Fm, 400 m Weiderfjellet (quartzite) Fm, 300 m HORNSUNDIAN DIASTROPHISM Sofiekammen Gp (Cambrian) Nordstetinden (dolostone) Fm, 150 m Gn~lberget (marble) Fro, 250-300 m Slaklidalen (limestone) Fm, 10-120 m Vardepiggen Formation, 130-215 m Bfftstertoppen (dolostone) Fro, 100-150m JARLSBERGIAN DIASTROPHISM Sofiebogen Gp (Proterozoic) G~shamna (phyllite) Fm, 1500-2500 m H6ferpynten (dolostone) Fm, 120-710m Slyngfjellet (conglomerate) Fro, 10-500m TORELLIAN DIASTROPHISM Torellbreen Supergp (three groups) Deilegga Gp Bergskardet Fm, 500+ m Bergnova Fro, 1800m Tonedalen Fm 1200+ m WERENSKIOLDIAN DIASTROPHISM Eimfjellet Gp (two subgroups plus two formations) Vimsodden Subgp (three formations, Birkenmajer 1993) Jens Erikfjellet Fm, 1100m Elveflya Fro, 200 m Nottinghambukta Fm, 1550m Skgdfjellet Subgp (four formations*)

10.7.1

West of Hansbreen

West of Hansbreen and north to Torellbreen there is a well exposed terrane which, in spite of intense tectonism, with many thrust units and few continuous sections, has yielded a coherent stratigraphy described in many papers from Birkenmajer (1958) to Birkenmajer (1993). His 1991 papers describe the earlier work with valuable detail hitherto not generally available. This immense contribution is accepted here with only minor comment. The scheme has been broadly accepted by the Norsk Polarinstitutt in their l:100 000 map C12G (Ohta & Dallmann 1992) and also by the Russian geologists under the leadership o f Krasil'shchikov who have independently worked there. This particular area is referred to here as the Vimsoddenlsbjornhamna Terrane. The succession is summarized as follows, except the Dunoyane Formation is probably not the youngest (see Fig. 10.5).

SOUTHWESTERN AND SOUTHERN SPITSBERGEN

193

Fig. 10.5. Stratigraphic schemes for the Precambrian succession of southern Wedel Jarlsberg Land.

member. From these observations and without knowing the distribution of the Deilegga divisions it was probably mistakenly concluded (Harland, Hambrey & Waddams 1993) that the Slyngfjellet Fm was older than the Deilegga rocks. It now appears that the Slyngfjellet facies may not be limited to one horizon. Deilegga Gp. Little had been written about the three formations in his Deilegga Gp until Birkenmajer (1992, 1993) described them as follows. Bergskardet Fm >500m. This is a green phyllite-slate and chlorite complex with light quartzite intercalations Bergnova Fro, 1800m. This was the middle Deilegga unit prior to Birkenmajer (1975). Green to black, yellow weathering phyllite and chlorite slates with intercalations of thin dolostone, limestone with pyritiferous shale and secondary gypsum. Birkenmajer (1960) referred to alum shales in this division. Tonedalen Fro, 1200m. The following three-fold division was formally defined by Birkenmajer (1993). Iskantelva Mbr, 100-1100m green and black (yellowish weathering) phyUites, slates and chlorite schists with thin dolostone and quartzite intercalations in the lower part and in the upper 300m pink-white quartzites. Czerny et al. (1993a, b) compared the lithology with that of the G~shamna Fm but correlation was rejected by Birkenmajer because of the stratigraphic order. On the other hand the map B12G (1992 edition) mapped this unit as G~shamna; but see discussion in section 10.9 Nannbreen Mbr, c. 50m is a sequence of carbonates, arenaceous and phyllitic rocks. Lipertoppen Mbr, c. 150m thins to 10m to NW is a quartzite metaconglomerate unit of mainly calcareous quartzite clasts with a minority of black marble and pink rhyolite volcanic clasts. Eimfjellet Gp, c. 4.3km (Birkemaaajer 1958, 1992). The group comprises the Vimsodden and Sk~lfjellet subgps and two formations beneath them: Steinvikskardet and Gulliksenfjellet (from official place name spelling Gullichsenfjellet). In 1991 Birkenmajer correlated the Skalfjellet

Subgroup with the two lower members of the lower (Nottinghambukta) formation of the Vimsodden Subgroup (Fig. 10.5). Vimsodden Subgp, c. 3.3 km. The Vimsodden 'series' was introduced as the lateral equivalent of the Sk~lfjellet 'Series' in the upper part of the Eimfjellet Fro. It consists of phyllites and slates intercalated with amphibolites, limestones, and varved quartz schists containing quartzite boulders first thought to be a marine tillite (Birkenmajer 1958, 1960). It was redefined and reinterpreted (e.g. Birkenmajer 1991, 1993). There were two constituent formations Elveflya and Nottinghambukta each with three members. In Birkenmajer's (1993) revision the uppermost member was separated as the Jens Erikfjellet Fm leaving the Elveflya Fm with the two lower members. Jens Erikfjellet Fm (Czerny et al. 1992; Birkenmajer 1993 raised from Member rank), c. 1100m consists mainly of metabasites, pillow lavas and tufts with subordinate paragneisses and schists. Rock types include greenstones and greenschists (the bulk of the formation), acid metavolcanics including porphyrites and minor muscovite graphite and quartzite schists with calc-schist intercalations and dolostone or dolomitic limestone lenses. At Elveflya is a green meta-conglomerate, 1-5m of tectonized quartzitic and granitiod clasts. Elveflya Fro, 2000 m (divided by Birkenmajer 1993) Skoddebukta Mbr, l l00m pale quartz-schists and quartz-chlorite schists and some black muscovite-graphite schists with amphibolite and quartz~ albite paragneiss intercalations. Middle Mbr, 300m quartz schists with three grey limestone marble bands. Vimsa Mbr, 600m (Lower member of Birkemnajer 1992). Light bluish quartz- and quartz-muscovite schists with two main meta-tilloid units separated by laminated quartz sericite schists. The metatilloids were first suggested as tillite by Birkenmajer in 1958, an opinion shared after further visits (Harland 1978; Harland, Hambrey & Waddams 1993). Alternative explanations have been suggested such as by tectonic shearing of sandy current ripples in a flaser-bedding association

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(Birkenmajer 1991, p. 44). However, the majority of outsize clasts better fit the hypothesis of ice-rafted s t o n e s - mainly of dolostone with minor amounts of quartzites and at least one observed dropstone structure in a less intensely deformed facies. Flaser structure, although also present, could not account for the composition, sizes and shapes of the stones. The preferred glacial origin need not conflict with Birkenmajer's flaser hypothesis because they relate to different objects. The whole formation is highly compressed and sheared typically producing a crenulated phyllite in which the outsize clasts have been d e f o r m e d - some flattened and some elongated, e.g. 1 5 • 2 1 5 lcm. Nottinghambukta Fro, c. 1.5km (divided Birkenmajer 1993). The formation is well developed at the coast of the eponymous bay. Kvisla Mbr, 700 m varied. Pyttholmen Mbr, 500 m of green muscovite- or chlorite-epidote schists. Kvislodden Mbr, 350 m of slates, paper shales and phyllites. Skhlfjellet Subgp. The subgroup has been described by Birkenmajer & Narebski (1960) Narebski (1960a, b) and Smulikowski (1960a, 1965, 1968). It consists largely of metamorphosed basic magmatic rocks including pillow lavas. This subgroup occupies ground to the south and south east of the Vimsodden Subgroup. Brattegga (amphibolite) Fro, 300-500m. Dark green to black epidote amphibolites with a structure suggestive of pillow lavas. This metavolcanic complex contains thin quartzite intercalations. AngeHfjeHet (amphibolite) Fin, 0-200m. Coarse-grained light green massive epidote amphibolites similar to gabbro in appearance. Gangpasset (migmatite) Fro, 0-100m. Comprises migmatites and granitoid rocks occurring as lenticular body within a predominantly amphibolite complex. It contains a meta-tilloid psephite unit up to 15 m thick. TorbjornsenfjeHet (amphibolite) Fro, 350-600 m. Medium to fine-grained epidote to biotite amphibolites are the major components alternating with fine green to dark green quartz-feldspar-hornblende-mica schist. The Angellfjellet Fm and the 'Gangpasset' (migmatite) Formation appear to be local facies or members of the Brattegga (amphibolite) Formation which correlates best with the Pyttholmen member of the Nottinghambukta Formation. Correlations of the Torbjornsenfjellet Formation with the Kvislodden member is not so obvious. The geochemestry of these rocks has been described by Narebski (1960) and Smulikowski & Kozlowski (1994). The other facies of interest, interspersed within the basic volcanics and gabbro-rich beds of the SkAlfjellet Subgp, are the feldspathic rocks which appear as lenses of granitic gneiss. Krasil'shchikov & Koroleva (1979) suggested an origin as rhyolitic tufts or arkoses. Limited observations by the Cambridge group recorded no evidence of original magmatic structure. Steinvikskardet Fro, 100-250 m (Birkenmajer 1958-1975). Greenish micaquartz and biotite-epidote~luartz-schists in bands 10-50cm thick, alternating with light quartzites and green concordant amphibolites. Transitional boundary at concordant amphibolite. Gulliksenfjellet (quartzite) Fro, 500-850m (Birkenmajer 1958: raised to formation rank 1975) is formed of well-bedded, light coloured, laminated quartzites in beds 0.5-10m alternating with green to black chlorite-biotitemuscovite schists with intercalations of green amphibolites and some albite and microcline-bearing rocks. Gulliksenfjellet Fm rhyolite porphyry clasts in the Pyttholmen Fm gave a zircon magmatic age of 1130 Ma (Balashov e t al. 1995). The contact with the underlying Revdalen Fm is generally tectonic and may have been unconformable, but was mapped concordantly by Czerny e t al. (1992). Isbjornhamna Group, 2-3 km (Birkenmajer 1958-1992; Smulikovski 1960) The Isbjornhamna Gp, comprising the Revdalen (top), Ariekammen, and the Skoddefjellet fms, is the oldest complex of rocks exposed in the Vimsodden-Isbjornhamna terrane. The Revdalen Fm (250-300 m) is of grey greenish to yellowish garnet micaschists (muscovite or bi-mica) and paragneisses without marble or calc-schist intercalations, which distinguish and define the underlying formation. The Ariekammen Fm (500-1500m) consists of psammitic to semipelitic schists alternating with grey marbles, many of the schistose beds are brown and have a recognizable calcite content and may be transitional to the marbles. The Skoddefjellet Fm (> 1000m) consists of grey, green to yellowishweathering garnet mica schists, predominantly with muscovite and paragneisses, with plagioclase and biotite as described by Smulikowski (1960b, 1965).

Isotopic ages have been proposed for these oldest rocks as follows: Gayer e t al. (1966) found a K - A r age for biotite from the lowest formations as 565 and 594 Ma. Peucat, Dallmeyer & Teben'kov (Ohta 1992) from zircons gave tentative ages of 1130 and 1135 Ma. Teben'kov e t al. (in prep) recorded garnet twomica schist with a preliminary metamorphic Rb-Sr age e. 940-950 Ma (text of map C13G, p. 42). An alternative scheme of Czerny e t al. (1992) redefined the Eimfjellet Gp as below. That part of their scheme is favoured here because it distinguishes established early Neoproterozoic strata from the overlying Elveflya Fm. Thus units in Birkenmajer's Vimsodden Subgroup are separated by the major Vimsodden-Kosibapasset Fault (VKF). Eimfjellet Gp (Middle Proterozoic) s e n s u Czerny e t al. Pyttholmen Fin (with acid igneous rocks from which Balashov e t al. (1995), suggested a magmatic age of 1200 Ma, a regional metamorphic age of 930 Ma, and with inherited zircons of 2500 Ma).

GulliksenfjeHet Fm Bratteggdalen Fm Skfilfjellet Fin (in part equivalent to the upper two formations). The Sk~dfjellet rocks yielded Rb-Sr and zircon (magmatic) ages of 1100-1200 Ma (Balashov e t al. 1996b) and detailed petrological data.

Eimfjellbreane Fm Skjerstranda Fm The Eimfjellet Group follows conformably on the Isbjornhamna Group. This reclassification is supported by Birkenmajer's correlation table (1992, p. 29) simplified here Fig. 10.5. In this work the Vimsodden-Kosibapasset Fault is taken as marking a major break in the sequence (i.e. a faulted unconformity) which divides a more restricted Vendian Vimsodden Group above (to the north) from a much older basement comprising a newly defined Eimfjellet Group (Czerny e t al. 1992) and a relatively concordant Isbjornhamna Group below of established mid-Proterozoic age (Balashov e t al. 1995). Formations are the observed stratal units which may (to express an opinion about their relationships) be combined into groups. The opposite procedure to define groups and divide them into formations has led to some of the above confusion and is not an international convention.

10.7.2

Early Paleozoic and Proterozoic strata east of Hansbreen

T h e rocks in this s u b t e r r a n e are described as in B i r k e n m a j e r ' s sequence, a n d m a i n l y with his description, while using s o m e o t h e r n a m e s to a v o i d implicit c o r r e l a t i o n either west o f H a n s b r e e n or south of Hornsund.

Hornsund Supergp Sorkapp Land Gp, 1400 m no fossils have been recorded from Wedel Jarlsberg Land. By correlation with Sorkapp Land fossiliferous units the group is Canadian in age. Birkenmajer (1978) consolidated earlier results from Major & Winsnes (1955) for Ordovician and Cambrian stratigraphy of the Hornsund area (southern Wedel Jarlsberg Land and Sorkapp Land). His accounts were given according to a unified nomenclature for the whole of southern Spitsbergen. Hornsundtind (limestone) Fro, 500 m in Sorkapp Land. The formation is of light to dark grey to black bituminous limestones passing down transitionally into pinkish grey limestones. Whereas this unit is best developed in Sorkapp Land it crops out as the most extensive unit throughout the length of the mountain range (Luciakammen) that extends north from Luciapynten nearly 20 km to the northernmost exposure at Aulrabben with only one small outcrop east of Mfilbacherbreen (Birkenmajer 1978, fig. 2). Two members have been distinguished south of Hornsund and no fauna was described from Wedel Jarlsberg Land. The correlation is lithological with that to the south and the fauna is as described in the south by Major & Winsnes (1955). Nigerbreen (limestone) Fro. The formation occurs only in the southern part of Luciakammen and at Fiskcknatten in the north but appears to wedge out between. It is defined in Sorkapp Land where it is 80 m thick but is probably less in Wedel Jarlsberg Land where it hardly shows on the map (Birkenmajer 1978, fig. 2). Dusken (limestone) Fro, 100m. This thin-bedded, grey, black-laminated limestones with yellow laminae and with black cherts is defined in Wedel Jarlsberg Land. It is thinner in Sorkapp Land (20-30m). It crops out through most of the length of Luciakammen. No fossils have been recorded from the formation.

SOUTHWESTERN AND SOUTHERN SPITSBERGEN

Luciapynten (dolostone) Fm, 400 m. The formation is made of dolostone, calcareous - massive or thick-bedded with black or blue chert intercalations with sponge-like (stromatolitic) structures. It is defined in Wedel Jarlsberg Land at Luciapynten and is exposed through the southern part of Luciakammen, the lower strata being mostly covered by ice. Wiederfjeilet (quartzite) Fro, 150m. This arenaceous, quartzite and dolomitic formation is defined in Sorkapp Land, but extends north into Wedel Jarlsberg Land where an extensive outlier of the lower member rests directly on Sofiekammen Group rocks (Cambrian) at Nordstetinden. Goi~sbreen Mbr (very limited occurrence) in the Sofiekammen range was noted by Birkenmajer and no outcrop is seen on his map (fig. 2). It is of dark grey calcareous shales and thin blue quartzite layers. Paierlbreen Mbr, 150m of dolomitic sandstone with fragments of the underlying Nordstetinden (dolostone) Fro. Sofiekammen Gp, 635-850m (Birkenmajer 1958, 1978) Nordstetinden (dolostone) Fro, 150m (Birkenmayer 1958, 1978) Nordstebreen Mbr, 150m (Birkenmajer 1978), of platy dark grey-black (yellow-weathering) dolostone in three layers, 1-10cm, alternating with yellow mainly dolostone 1-2 cm layers. Hansbreen Mbr, 100m (Birkenmajer 1978) of light or dark grey to bluish (yellow weathering) massive or poorly bedded dolostone. Grey dolostone sometimes alternates with black bituminous dolostone. Gnfilberget (marble) Fro, 250-300m (Birkenmajer 1959, 1978). Massive limestone marble with pink calcite or red jasper veins; no fossils were recorded. Slaklidalen (limestone) Fro, 25-120 m (Birkenmajer 1975, 1978). Black to grey limestone is sometimes dolomitic, bituminous or arenaceous and often thin-bedded; correlated with the richly fossiliferous Slakli Subgp of Late Early Cambrian age (Major & Winsnes 1955), but fossils in Wedel Jarlsberg Land were not specified. Vardepiggen Fro, 110-130 m Flogtoppane Mbr, 30-40 m, yellow dolostone or grey limestone pass down into black to grey graphitic shales often with sedimentary breccias. Midifjellet Mbr, 5 - 5 5 m , black to dark grey limestone, often shaly or phyllite with indeterminate trilobite fragments. Olenellusbreen Mbr, 44-65 m (Birkenmajer 1978) of green to black shale with sedimentary breccias with flattened imprints and exoskeletal fragments of olenellids and anemone burrows Dolopichnus. A late Early Cambrian age was suggested. Blfistertoppen (dolostone) Fro, 100-150m. Blue-black, yellow weathering arenaceous dolomitic rocks passing into pure dolostone or dolomitic limestone. No fossils are recorded from Wedel Jarlsberg Land. A basal conglomerate is said to rest with angular unconformity on the Bogstranda unit which is correlated with the Ggtshamna phyllite Fm (south of Hornsund); but the section at Islova-Lovetanna (Birkenmajer 1978, p. 14) shows a concordant relationship. Sofiebogen Gp. This is part of the Precambrian succession and was described by Birkenmajer (1958 et seq.), as at the beginning of this section, for the whole of south Spitsbergen. However, other names have been introduced here (e.g. from Harland 1978) for this terrane (east of Hansbreen and north of Hornsund) to facilitate discussion of correlation between the terranes. They are distinguished by asterisks. The sequence appears to be continuous and demonstrably younging to the east so that the rocks have been overturned with a steep westerly dip. *Bogstranda unit, 2.0km. This unit has been correlated with the Gfishamna Fm south of Hornsund and a separate formal name may not be necessary except for the purpose of discussion so as not at first to assume identity. The rocks are better developed here and their relation to the older beds is well exposed. The strata are very largely pelitic, intercalated with seven quartzite shale horizons (up to 60m) in the lower 1000 m where some dolostone beds occur up to 5 m. A limestone bed occurs above the quartzite beds. The pelites are phyllites in many shades of green and black. The former probably indicate a volcanic component and the latter a biogenic input in the absence of volcanic material. The quartzite shale horizons, the quartzitic sandstones and/or quartzites are white to rusty brown weathering. Some chert fragments occur at their soles and the associated pelites may be graphitic. At Bogstranda the dolostones may contain silicified ooids. The limestones are reminiscent of Cambrian facies. Although the thickness south of Hornsund may total more than 3 km the lower conta