Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1990 Crustal Extension in the Southern Snake Range and Vicinity, Nevada-Utah: An Integrated Geological and Geophysical Study. A. H. m. shah Alam Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Alam, A. H. m. shah, "Crustal Extension in the Southern Snake Range and Vicinity, Nevada-Utah: An Integrated Geological and Geophysical Study." (1990). LSU Historical Dissertations and Theses. 4967. https://digitalcommons.lsu.edu/gradschool_disstheses/4967 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. 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Shah, Ph.D. The Louisiana State University and Agricultural and Mechanical Col., 1990 UMI 300 N. Zeeb Rd. Ann Aibor, MI 48106 Grustal extension in the Southern Snake Range and vicinity, Nevada-Utah: an integrated geological and geophysical study A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Geology and Geophysics by A. H. M. Shah Alam B.Sc(Hons.), The University of Dhaka, Bangladesh, 1981 M.S., Louisiana State University, 1985 August 1990 ACKNOWLEDGEMENTS The author thanks Professor Rex H. Pilger, Jr., for serving as the major professor, and for his able guidance through the ups and downs of this research. Professor Dag Nummedal, the minor professor, helped with the seismic stratigraphic framework of land-locked continental basins of this study. Professor Jeffrey Nunn helped with the gravity modeling and with constructive geophysical comments of crustal extensional models which structural geologists tend to overlook. Discussions with professors Vindell Hsu and Charles McCabe on various aspects of this research were beneficial. The author thanks Professor Paul M. Walthall (Department of Agronomy) for serving as the external committee member for the dissertation defense. Discussions with Professors John Oldow (Rice University) and Laura Serpa (University of New Orleans) during their visits to Louisiana State University were stimulating. Frank Royse, now retired from Chevron, kindly provided his one unpublished geologic section across eastern Basin and Range Province and shared his thoughts about this research. My collective thanks to the audiences during my poster and oral presentations based on various aspects of this research at Geological Society of America (1987, 1989), American Geophysical Union (1989), Graduate Student Research (LSU) (1989), Volcanoes for Lunch (LSU) (1989), Fluid Seminar (LSU) (1989), and Exxon Production Company (1989) meetings, who provided thought-provoking comments and helped to evaluate this research at every meeting. Confucius once said "one out of every three persons can teach you something"; with that the author reminisces the camaraderie of geophysics graduate students at LSU including Linda Kauth, Terry Angelich, Brian Butler, Jeff Lobao, Bernard Coakley, Yeadong Kim, David Lisle, Mancheol Suh, Vicki Iliff, B. Wayne Driskill, David Evans and Sharon Walley. My sincerest thanks, however, are for my supportive parents. The author is grateful to the Union Oil Company of California (Mr. Jean Paul Chauvel, Senior Geologist, UNOCAL) for providing the seismic and the bore hole data. Viki Bankey of United States Geological Survey provided digital gravity data. Several Oil Companies including Badger Oil Corporation, Forest Oil Corporation, Oxy USA Inc., and Wolverine Exploration Company provided additional seismic and bore hole data. Sigma Xi, the Scientific Research Society, supported this study with a grant. The Department of Geology and Geophysics (LSU) provided a grant to meet cartographic and duplication expenses involved in the final manuscript preparation. TABLE OF CONTENTS ACKNOWLEDGEMENTS ii TABLE OF CONTENTS iv LIST OF TABLES vii LIST OF FIGURES viii ABSTRACT X CHAPTER ONE: INTRODUCTION 1 CHAPTER TWO! REGIONAL GEOLOGY & GEOPHYSICS 6 Location of the study area 6 Regional Geophysics 9 Crust and Moho 9 Seismicity 10 Extension Direction 10 Gravity, Magnetics and Topography 11 Heat-flow 14 Extension of Heterogeneous, anisotropic crust 14 Regional Tectonic History 15 Precambrian Rifting 15 Paleozoic Passive Margin 16 Mesozoic Orogeny 16 Cenozoic Crustal Extension 17 Regional Geology 17 Precambrian to Paleozoic 17 Mesozoic 20 Cenozoic 21 Early Cenozoic Sediments 21 iv Mid-Cenozoic Volcanic Rocks 22 Late Cenozoic Basin-fill 23 CHAPTER THREE: DATA 24 Seismic Data 25 Well Data 26 The Commodore Resources Outlaw # 1 Federal 2 6 Fletcher Federal # 1 33 CHAPTER FOUR: METHODOLOGY 36 Integrated Interpretation of Seismic Lines 37 Integration of Gravity Data 39 Geometric Restorations 41 Compaction 42 CHAPTER FIVE: HAMLIN AND SOUTHERN SNAKE VALLEYS 63 Introduction 63 Basin-fill Stratigraphy 64 Pre-Cenozoic 64 Cenozoic 65 Structure 72 Snake Range Decollement Reflection 76 Onset of Crustal Extension 79 Magnitude of Upper Crustal Extension 80 CHAPTER Six: CORE COMPLEX EVOLUTION 83 Introduction 83 Snake Range Core Complex 84 Geologic Interpretation 85 Subsurface Observations 86 Core Complex Uplift 89 v Characterization of Uplift 89 Mechanisms for Uplift 89 Evolutionary Model 94 Pre-extension 101 Onset of Extension 101 Development of Low-angle Normal Faults 103 Uplift of Lower Plate 103 CHAPTER SEVEN: CONCLUSION 105 BIBLIOGRAPHY 107 APPENDIX 1: DATA 121 VITA 12 6 vi LIST OF TABLES 1. Plutons in the southern Snake Range 21 2. Stratigraphic thicknesses encountered in the 32 Commodore Resources well are compared with the outcrop thicknesses 3. Gross lithologies, interval velocities and 39 density values of the basin-fill sequences 4. Parameters of the exponential relation between 44 porosity and depth 5. Magnitude of upper crustal extensions along 82 seismic profiles A1. Seismic line-lengths in the Hamlin Valley 121 A2 . Seismic data processing sequence 122 A3. Fletcher Union Federal NO. 1: well resume 123 A4. Fletcher Union Federal NO. 1: electric log tops 123 A5. Commodore Resources Outlaw # 1 Federal: well 124 resume A6. Commodore Resources Outlaw # 1 Federal: electric 124 log tops A7. Identifications of aerial photographs 125 v i i LIST OF FIGURES 1. Continental crustal extensional models 3 2. Locations of the study area and the data, and 7 the geology 3. Aerial photograph of parts of the southern Snake 8 Range, and the southern Snake and the Hamlin Valleys 4. Complete Bouguer Gravity map of the study area 12 5. Regional gravity low of northern Basin and Range 13 Province 6. Stratigraphic section for the study area 19 7. Stratigraphic cross-section utilizing bore boles 27 8. Stratigraphy penetrated in the Commodore 28-29 Resources Outlaw # 1 Federal 9. Stratigraphy penetrated in the Fletcher Union 30 Federal No. 1 10. Seismic line 08: uninterpreted and interpreted, 45-49 migrated and unmigrated stack, and depth sections with gravity profiles, seismic interval velocities, and density values; geometric restorations of the depth section 11. Seismic line 20: uninterpreted and interpreted, 50-52 migrated and unmigrated stack, and depth sections with gravity profiles 12. Seismic line 06: uninterpreted and interpreted, 53-55 migrated and unmigrated stack, and depth sections with gravity profiles 13. Seismic line 07: uninterpreted and interpreted, 56-58 migrated and unmigrated stack, and depth sections with gravity profiles 14. Seismic line 09: uninterpreted and interpreted, 59-61 migrated and unmigrated