ABSTRACT The Late Cambrian Jordan Sandstone is subdivided into four members in southeastern Minnesota. Younging upward these are the Norwalk, Van Oser, Waukon and Sunset Point Members. The very fine-grained feldspathic Norwalk and Waukon Members are interpreted as offshore to lower shoreface lithofacies. The medium-grained quartzose Van Oser Member is interpreted as a middle and upper shoreface lithofacies influenced by episodic sedimentation. The fine-grained feldspathic and dolomitic Sunset Point Member is interpreted as a tide-influenced shallow marine lithofacies; sedimentation was transitional from siliciclastic shoreface deposition to locally shoaling- upward carbonate deposition most probably associated with a laterally prograding offshore platform or development of laterally accreting and migrating tidal islands. Deposition of the Jordan Sandstone occurred in an epicontinental shallow marine environment during a transition from marine regression, typified by Norwalk, Van Oser and Waukon strata, to constant subsidence coupled with progradation of carbonate sediments, typified by Sunset Point strata. Progradation of Sunset Point strata resulted from locally increasing rates of carbonate sedimentation. The provenance area of the Jordan Sandstone was the continental craton interior. Diagenetic Processes occurred under low temperatures and pressures. The paragenetic sequence in order of occurrence is: the precipitation of thin quartz syntaxial overgrowths and potassium feldspar expitaxial overgrowths, the precipitation of hematite, dolomitization, the dissolution of potassium feldspar and dolomite, the precipitation of calcite, the dissolution of calcite and a second precipitation of hematite. Lithostratigraphic units (i.e., members) of the Jordan Sandstone in Minnesota demonstrate conformable relationships and have diachronous lower and upper boundaries; the Cambrian-Ordovician boundary is diachronous and typically gradational in southeastern Minnesota. Sunset Point strata represent a viable member of the Jordan Sandstone and are best not included in the overlying Ordovician Oneota Dolomite as some workers have suggested. II ACKNQWT.EPGEMENTS Preparation of this thesis has greatly benefited from the assistance, advice and co-operation of many individuals. Above all, I gratefully acknowledge my thesis supervisor, Dr. Richard W. Ojakangas, of the University of Minnesota- Duluth who proposed this study, edited several drafts of the text and provided valuable suggestions for its improvement. Dr. Glenn B. Morey of the Minnesota Geological Survey was an enthusiastic supporter of the study and suggested to Dr. Ojakangas that it would be an excellent thesis topic. Drs. David G. Darby and Curtis Anderson of the University of Minnesota-Duluth and Dr. Glenn B. Morey of the Minnesota Geological Survey served as members of the thesis committee; they made helpful suggestions and critically reviewed the manuscript. To Brian Hayden goes my special thanks for his companionship and discussions in the field. I also thank Jodie Holmgren for typing drafts of the thesis. Partial funding of this study was provided by the Geology Department of the University of Minnesota-Duluth and the Minnesota Geological Survey. Finally, it is a pleasure to express my gratitude to my parents, Mr. and Mrs. Joseph W. Thomas, and my wife, Helen Earnshaw, for their constant encouragement. iii TABLE OF CONTENTS ABSTRACT •.•• . i ACKNOWLEDGEMENTS . iii TABLE OF CONTENTS iv FIGURES vii TABLES •• x PLATES x Chapter I INTRODUCTION • • • . • . • . • • • . • . 1 Pt1R.POSE . • • • • • • • • • • • • . • • • • . 1 METHODS OF STUDY • • • . • • • . 1 Field Work • . • • • • . • • 1 Laboratory Work • • • • . • • • • 2 PREVIOUS WORK • . • . • • • . • • . • . • • 4 History of Stratigraphic Nomenclature 4 Sedimentological Studies . • . • . 10 Chapter II LITHOSTRATIGRAPHY • . • . • . • . • 11 JORDAN SANDSTONE • . • . • • . • . 11 NORWALK MEM.BER • • • • • • • • • • • 17 Physical Sedimentary Structures 18 Biogenic Sedimentary Structures 21 St. Lawrence - Norwalk Contact • • 23 VAN OSER MEMBER • • • • • • • • • • • • • • • • 26 Physical Sedimentary Structures . • 26 Biogenic Sedimentary Structures • . 31 Norwalk - Van Oser Contact • . • • 33 WAUKON MEMBER • • • • • • . • • • . 34 SUNSET POINT CCOON VALLEY) MEMBER ••••. 34 Physical Sedimentary Structures • . 37 Biogenic Sedimentary Structures • • • 38 Van Oser - Sunset Point Contact . • . 40 Sunset Point - Oneota Formation Contact 42 Chapter III PALEONTOLOGY . • . • • . • • . • . 43 MACROFOSSILS . 43 MICROFOSSILS . 44 Chapter IV PALEOCURRENTS . 47 iv Chapter V PE'rR.OLOGY' • • • • • • • • • • • • 56 OPERATIONAL DEFINITIONS . • • . • • • • • . 57 NORWALK MEMBER . • • • • • 58 Mineralogy . • . • . 58 Texture . 63 VAN OSER MEMBER • . • • . • • • • 67 Mineralogy . • • . • . • . • 67 Texture . • • • . • 77 WAUKON MEMBER. • • • • • • • • • • • • • • • 78 SUNSET POINT (COON VALLEY) MEMBER ...... .18 Mineralogy • • . 78 Texture . 90 HEAVY MINERALS . • . • • 93 Chapter VI DIAGENESIS • . • • 95 MINERALOGY 95 Cementation Sequence • 102 TEX.TORE • • • • • • • • • 104 Primary Porosity • 108 Secondary Porosity • • 108 Chapter VII INTERPRETATION AND DISCUSSION • • • . • . 113 ENVIRONMENTS OF DEPOSITION • • • • • . • • • . 11·3 Norwalk Member . • 119 Van Oser Member . • 128 Waukon Member . • . • • . • . • • . 133 Sunset Point (Coon Valley) Member ••.• 135 PROVEN'ANCE • • • • • • • • • • • • • • . • . • 144 DIAGENETIC HISTORY • • . • . 151 Dolomitization . • . • •• 157 TECTONIC SETTING AND CYCLICITY 159 CAMBRO - ORDOVICIAN BOUNDARY • . • • . • . 161 Chapter VIII CONCLUSIONS 167 REFERENCES CITED •• 171 v APPENDICES APPENDIX 1: Index Map of Minnesota Counties . •. 186 APPENDIX 2: Measured Section Location Descriptions . APPENDIX 3: Measured Section Descriptions and Thin Section Sample Locations . 189 APPENDIX t.. : Paleocurrent Data 202 APPENDIX 5: Monocrystalline Quartz Extinction Data . 204 vi FIGURES Figure 1. Location map of the 12 measured sections of Jordan Sandstone used in this study • . • . • • • • • 3 2. History of stratigraphic nomenclature • . • • . 5 3. Stratigraphic column of Upper Cambrian rocks in Minnesota • . ' . • • • • . 12 '-. Structural contour map of the top of the Jordan Sandstone in Minnesota • . 13 5. Isopach map of the Jordan Sandstone in Minnesota • . 15 6. Lithostratigraphy of Jordan Sandstone in Minnesota • . • . • • . • . 16 7. Stratification geometry terminology • • • • 19 8. Bedding thickness terminology • . • . • • . 20 9. Typical exposure of dolomitic siltstones of the St. Lawrence Formation • • . • 25 10. Typical exposure of mottled sandstones of the Norwalk Member • . • • . • 25 11. Typical exposure of trough cross- stratif ication in the Van Oser Member . • . • . • . • . 28 12. Unconunonly thick cosets of tabular cross-stratification in the Van Oser Member . • • . • . • . 28 13. Continuous and discontinuous planar parallel stratification in the Van Oser Member . • . • 30 l/a. Flat-pebble rip-up clast horizon in the Van Oser Member • • . • • • • • . 30 15. Arencolites as it typically occurs in the Van Oser Member . • . • • 32 16 .. Skolithos as it typically occurs in the Van Oser Member • . • . • • • 32 17. Schematic cross-section of the Jordan Sandstone from northeastern Iowa to central Wisconsin . • • • • • . • . 36 18. Laterally linked hemispheroid stromatolites in the Sunset Point (Coon Valley) Member •••.•••..•. 39 19. Green muds and silts interstratified with fine sands in the Sunset Point (Coon Valley) Member .•..•• 39 20. Planolites in the Sunset Point (Coon Valley) Member ••••••.•• . 41 21. Planolites in the Sunset Point (Coon Valley) Member • • . • . • • • • • • 41 vii 22. Paleocurrent rose diagrams for the Van Oser Member of the Jordan Sandstone in Minnesota . • • • • • • • • 48 23. Paleocurrent rose diagrams for the Norwalk Member of the Jordan Sandstone in Minnesota • . • • 49 2t.i.. Paleocurrent rose diagrams for the Sunset Point (Coon Valley) Member of the Jordan Sandstone in Minnesota . • • 50 25. Paleocurrent rose diagrams summarizing all measurements taken in the Norwalk, Van Oser, and Sunset Point (Coon Valley) Members of the Jordan Sandstone in Minnesota 51 26. Paleocurrent rose diagrams summarizing all measurements taken in the Jordan Sandstone in Minnesota 52 27. Detrital composition of Norwalk Member samples . • • • . • • • • • . • 62 28. Photomicrograph of a typical Norwalk Member specimen • . • . • . • 64 29. Types of framework grain contacts • . • . • • . 66 30. Detrital composition of Van Oser Member samples . • • . • • . • . • • • 68 31. Photomicrograph of a typical Van Oser Member specimen . • • . • . • • 75 32. Detrital composition of Sunset Point (Coon Valley) Member samples ... 82 33. Photomicrograph of a typical dolomitic wackestone in Sunset Point (Coon Valley) Member ..••....... 83 3i.. Photomicrograph of a typical arkose in Sunset Point (Coon Valley) Member •..• 84 35. Photomicrograph of a typical crystalline dolomite in Sunset Point (Coon Valley) Member • • • . • • • • • • • • 85 36. Photomicrograph of an oolitic packstone in Sunset Point (Coon Valley) Member . 86 37.• Photomicrograph of oolite aggregates in a Sunset Point (Coon Valley) Member specimen • • . • • • • . • . 91 38. Photomicrograph of a well rounded green tourmaline grain, Van Oser Member 94 39. Photomicrograph of a rounded etched garnet grain, Van Oser Member 94 I L..O. Photomicrograph of authigenic epitaxial \ potassium feldspar overgrowths on \ detrital feldspar cores, Norwalk Member • • • • • • . • . • •