ANHYDRITE-CARBONATE CYCLES OF THE ORDOVICIAN BAUMANN FIORD FORMATION, ELLESMERE ISLAND, ARCTIC CANADA: A GEOLOGICAL HISTORY by Grant Dilworth Mossop, B.Sc.(Hons.), M.Sc. Thesis submitted for the degree of Doctor of Philosophy of the University of London Geology Department, Imperial College of Science and Technology, London, England. November, 1973. A 11 ABSTRACT The Baumann Fiord Formation of central Elle'.-lmere Island is made up of between 700 and 1,500 feet of concordantly compounded carbonate — anhydrite cycles. The cycles, which average 12 feet in thickness, characteristically comprse a basal shallow—marine lime mudstone facies, followed upwards by an intertidal facies with algal stromatolites, in turn overlain by a supratidal anhy- drite facies, the ~•mole bounded top and bottom by erosion surfaces. Each of these regressive sequences is representative of a discrete sabkha sedimentation cycle and the formation as a whole was built up through repetitous superimposition of successive sabkha cycles. Much of the Baumann Fiord anhydrite underwent early—stage compactional flow, producing layered and laminar anhydrite. Deep burial, accompanied by pervasive recrystallization, further modified the textural character of some of the anhydrite, notably that of the seaward portion of the sedimentary wedge. The Ellesmerian Orogeny (Middle Devonian to Early Mississippian) brought folding and, where deformation was excessive, it caused remobilization and flow of the anhydrite. Subsequent thrust— faulting (Tertiary Eurekan Orogeny) produced shear zones at various levels within the formation. During exhumation the basal reaches of the formation locally underwent hydraulic fracturing. Water from the underlying stratamoved up into the evaporites and hydrated the anhydrite to form secondary gypsum. The excess calcium sulphate liberated during this volume—for—volume replace- ment process precipitated in the fracture system, forming satin— spar veins. The latest stages of exhumation have taken place during the permafrost regime of Pleistocene and Holocene times. Hydration by present—day meteoric water promotes gypsification of only the outermost voneer of exposures, and in consequence much anhydrite is preserved essentially unaltered at outcrop. iii Ari<21.0 .1F,DGETETTTS This study was rupervi.sed by Dr. D.J. Shearman of the Imperial College, London. His guidance and encouragement in all phases of the research is most gratefully acknowledged. The author feels enriched for having had the opportunity to work so closely with a man of such infectious scientific enthusiasm and indomitable spirit. Sponsorship of the project was by the Geological Survey of Canada (Dr. D.J. McLaren, Director; Institute of. Sedimentary and Petroleum Geology; Calgary, Alberta, Canada). The G.S.C. under- wrote all expenses incurred in the field component of the study and provided much in the way of scientific and logistical guidance. Direct financial support, in the form of an Overseas Scholarship, was from the Royal Commission for the Exhibition of 1851, London. To both these institutions, the author expresses his sincere gratitude. Thanks are extended to the following persons for their help with the field phase of the study : Dr. R.L. Christie, who administered the project; Drs. H.P. Trettin, J.Wm. Kerr, R. Thorsteinsson, G. Davies and W.U. Nassichuk, who advised the author on matters of geology and logistics; Mr. D.S. Turner, who proved an able and companionable field assistant; and the pilots of Bradley Air Services and Dominion Helicopter Company, whose skill and willingness to try almost anything allowed the author access to very difficult terrain. Of the teaching staff at Imperial College, special thanks is extended to Drs. P.R. Bush and G. Evans for much helpful discus- sion pertaining to numerous facets of the research. Dr. Bush also critically reviewed parts of the manuscript and furnished advice on thesis compilation. For uncounted kindnesses, the author extends particular gratitude to Miss Mary Pugh, without whom the Sedimentology Department would surely cease to function. Technical advice and assistance from the following Imperial College personnel was greatly appreciated : Si wart and Martin iv Gill (Sedimentology); john Blount (Rock Cutting)! an Bruce Hougl' (Sedimentary Geochemistry). Mr. J. Gee and his staff did much immaculate photographic work for the author and provided tuition in aspects of photoprinting. Typing was done quickly and efficient- ly by Mrs. Janice Tipping. Brian Moss drafted a number of the figures. For contributing to productive discussion and for establish- ing a congenial atmosphere in which to work, appreciation is extended to fellow—students in the Geology Department of. Imperial College, and particularly to Hugh Dunsmore, Tony Corrigan, Stuart Smith and Steven Van der Haar. Finally, the author wishes to express his warmest appreciation to his wife, Ruth, for her encouragement during times of setback, and for her unfailing grace and devotion. TV'cLE OF CONTENTS Page INTRODUCTION 1 General Statement Purposes 2 CHAPTER 1 GEOGRAPHY AND GEOLOGY OF ELLESMERE ISLAND: A REVIEW 5 1.1 Introduction 6 1.2 Geography of Ellesmere Island 7 Location, Size and Population 7 Climate 7 Physiography 10 1.3 Field Methods 14 Access and Travel 14 Exposure Conditions 15 1.4 History of Geological Investigation 16 Early Work : Pre 1955 16 Recent Work : Post 1955 19 1.5 General Geology 19 Precambrian Shield 19 Franklinian Geosyncline 22 Sverdrup Basin 24 1.6 Stratigraphic Setting of the Baumann Fiord Formation 26 General Stratigraphy 26 Structural Trend and Thickness Variation 29 Ordovician Stratigraphic Nomenclature 30 Baumann Fiord Formation 31 Summary 33 CHAPTER 2 CARBONATE—ANEYDRITE CYCLES OF THE BAUMANN FIORD FORMATION 36 2.1 Introduction 37 2.2 The Sabkha Setting 39 The Recent Sabkha 39 Ancient Sabkha Cycles 46 vi Page 2.3 The Baumann Fiord Cycle 48 Erosion Surface 48 Description 48 Interpretation 48 Flat Pebble Conglomerate 51 Description 51 Interpretation 54 Lime Mudstone 56 Description 56 Interpretation 56 Algal Stromatolites 63 Descriptions 63 Interpretation 69 Dolomite 73 Description 73 Interpretation 73 Anhydrite 76 2.4 Summary and Conclusions 82 CHAPTER 3 COMPOSITE CYCLES FACIES VARIATIONS AND PALEOGEOGRAPHIC RECONSTRUCTION 86 3.1 Introduction 87 3.2 Section Descriptions 87 3.3 Vertical Variation in Sequence — Compound Cycles 104 3.4 Lateral Variation in Sequence — Facies Intertongu.ing 116 3.5 Paleoenvironmental Evolution of the Study Area 129 3.6 Paleogeography 130 CHAPTER 4 ANHYDRITE — ASPECTS OF DIAGENESIS TECTONISM AND METAMORPHISM 140 4.1 Introduction 141 4.2 Laminar Anhydrite 142 Displacive Growth of Nodular Anhydrite 142 Compaction of Nodular Anhydrite 142 Baumann riord Laminar Anhydrite 145 vii Page Aspects of Petrography 153 4.3 Massive Anhydrite 159 4.4 Influence of Tectonism on Anhydrite 165 4.5 Other Aspects of the Baumann Fiord Formation's Secondary History 173 Replacement Anhydrite 173 Anhydrite Fracture—Fill 174 Chert Concretions 178 CHAPTER 5 SECONDARY GYPSUM 179 5.1 Introduction 180 5.2 Background Considerations 181 Anhydrite—Gypsum Thermo—chemical Stability Relationships 181 Volume Increase on Hydration 182 Water Availability and Access Modes 184 5.3 Secondary Gypsum of the Basal Baumann Fiord Formation 185 5.4 Surficial Weathering—Product Gypsum 192 5.5 Summary and Conclusions 207 REFERENCES 209 APPENDICES 222 Appendix A Published Reference Maps of the Study Area 223 Appendix B Section Lithologic Logs 225 Appendix C Sulphur Isotope Data for Baumann Fiord Formation Sulphate Rocks 226 Appendix D New Paleontological Information on the Baumann Fiord Formation 227 Appendix E Franklinian Overburden Above the Baumann Fiord Formation — Trold Fiord Region 229 Appendix F Strontium Contents of Baumann Fiord Formation Anhydrite and Gypsum Rocks 230 viii LIST OF FIGURES Page CHAPTER 1 Figure 1 Index Map 8 Figure 2 Climatic Statistics - Ellesmere Island. Table. 9 Figure 3 Physiography - Ellesmere Island. Map. 12 Figure 4a Valley and Ridge Topography. Field Photograph. 13 b Dissected Plateau Physiography. Field Photograph 13 Figure 5a Frost-wedged blocks. Field Photograph. 17 Talus fans. Field Photograph. 18 Figure 6 Tectonic Subdivisions of Ellesmere Island. Map. 21 Figure 7 Paleo-physiography of the Frahklinian Geosyncline. Block Diagram. 23 Figure 8 Relationships Amongst the Geological Provinces - Ellesmere Island. Cross-Section. 25 Figure 9 Franklinian Stratigraphic Nomenclature. Correlation Chart. 28 Figure 10a Copes Bay - Baumann Fiord Contact. Field Photograph. 32 b Eleanor River Formation. Field Photograph. 32 Figure 11 Carbonate-Anhydrite Cycles. Field Photograph. 35 CHAPTER 2 Figure 12 Trucial Coast Sabkha. Cross Section. 42 Figure 13 Baumann Fiord Carbonate-Anhydrite Cycle. Schematic Drawing. 49 Figure 14 Purbeckian Sabkha Cycle - Warlingham Borehole. Slab Photograph. 50 Figure 15 Flat-Pebble Conglomerate. Field Photograph. 52 Figure 16a Flat-Pebble Conglomerate - Micrite Clasts. Photomicrograph. 53 b Flat-Pebble Conglomerate - Exotic Clasts. Photomicrograph. 53 Figure 17 Cross-Laraination - Lime Mudstone Facies. Field Photograph. 57 Figure 18 Massive Limestone. Field Photograph 58 Figure 19a Laminated Lime Mudstone. Photomicrograph. 59 ix Page Figure 19b Laminated Lime Mudstone. Photomicrograph. 59 Figure 20 Digitate Stromatolites. Field Photograph. 65 Figure 21 Polygonal Stromatolites. Field Photograph, 66 Figure 22 Domal Stromatolites. Field Photograph. 67 Figure 23 Coalesced Algal Heads. Field Photograph. 68 Figure