FRACTURE ANALYSIS OF CIRCUM-BIGHORN BASIN ANTICLINES, WYOMING-MONTANA by Julian Stahl A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Earth Science MONTANA STATE UNIVERSITY Bozeman, Montana November 2015 ©COPYRIGHT by Julian Stahl 2015 All Rights Reserved ii DEDICATION I dedicate this thesis to my brother, Manuel Stahl, who provided me with the inspiration and drive to pursue a degree that I am truly passionate about. iii ACKNOWLEDGEMENTS The research presented in this document would not have been as thought- provoking and thorough without the help of my mentors and peers. My advisor, Dr. David Lageson helped formulate the project idea and was fundamental throughout the course of my study in leading me in the right direction and always being available to answer questions. I would also like to extend my gratitude to my committee members, Dr. Colin Shaw and Dr. Jean Dixon, for providing me with the necessary assistance and expertise. I would also like to thank my fellow geology peers at Montana State University. Without the constant communication and discussions with Mr. Jacob Thacker, Mr. Travis Corthouts and Mrs. Anita Moore-Nall this project would not have come to fruition. I would also like to offer my sincere appreciation to my two field assistants, Mr. Evan Monroe and Miss Amy Yoder, for taking the time out of their lives to help unravel the geology of the Bighorn Basin in the field. I would like to express my gratitude to my entire family, Dr. Johannes Stahl, Ms. Gabriele Stahl and Mr. Roman Stahl, for supporting me and giving me inspiration to pursue my passion for geology throughout my undergrad and graduate career. This project would not have been possible without the financial support of Rocky Mountain Association of Geologists, Tobacco Root Geological Society, American Association of Petroleum Geologists, and Montana Geological Society. iv TABLE OF CONTENTS 1. INTRODUCTION ...........................................................................................................1 Bighorn Basin, Wyoming-Montana .................................................................................1 Research Objectives .........................................................................................................3 Research Question ...................................................................................................6 Previous Work .................................................................................................................7 Research Importance ........................................................................................................9 2. GEOLOGIC SETTING .................................................................................................10 Regional Stratigraphy ....................................................................................................10 Paleozoic ................................................................................................................10 Triassic and Jurassic ..............................................................................................13 Cretaceous ..............................................................................................................13 Cloverly Formation ....................................................................................14 Thermopolis Shale .....................................................................................14 Muddy Sandstone and Mowry Shale .........................................................15 Frontier Formation .....................................................................................15 Cody Shale .................................................................................................15 Mesaverde Formation ................................................................................16 Meeteetse Formation ..................................................................................16 Regional Structural Geology..........................................................................................17 Sevier and Laramide Orogeny ...............................................................................17 Foreland Basins of the Rocky Mountain Region ...................................................19 Bounding Tectonic Structures of the Bighorn Region ...........................................20 Timing of Adjacent Laramide Uplifts....................................................................22 Anticline Formation Mechanism ...........................................................................22 Laramide Deformation Styles ........................................................................................24 Non-crustal Shortening Models .............................................................................24 Crustal Shortening Models ....................................................................................25 3. METHODS ....................................................................................................................29 Google Earth Pro Lineaments ........................................................................................29 Data Collection ......................................................................................................29 GIS Processing and Rose Diagrams ......................................................................30 Google Earth Pro Accuracy ...................................................................................31 Outcrop Fracture Measurements ....................................................................................32 Data Collection ......................................................................................................33 Stereonet ................................................................................................................34 Statistical Comparison ...........................................................................................35 v TABLE OF CONTENTS - CONTINUED 4. RESULTS ......................................................................................................................36 Introduction ....................................................................................................................36 Elk Basin Anticline ........................................................................................................37 Overview ................................................................................................................37 Fold Classification .................................................................................................37 Lineament Analysis ...............................................................................................38 Fracture Analysis ...................................................................................................40 Horse Center Anticline Analysis ...................................................................................42 Overview ................................................................................................................42 Fold Classification .................................................................................................43 Lineament Analysis ...............................................................................................45 Fracture Analysis ...................................................................................................45 Oregon Basin Anticline ..................................................................................................46 Overview ................................................................................................................46 Fold Classification .................................................................................................48 Lineament Analysis ...............................................................................................49 Fracture Analysis ...................................................................................................49 Little Buffalo Basin Anticline ........................................................................................52 Overview ................................................................................................................52 Fold Classification .................................................................................................53 Lineament Analysis ...............................................................................................53 Fracture Analysis ...................................................................................................54 Crass Creek Anticline ....................................................................................................57 Overview ................................................................................................................57 Fold Classification .................................................................................................58 Lineament Analysis ...............................................................................................58 Fracture Analysis ...................................................................................................59 Thermopolis Anticline ...................................................................................................62 Overview ................................................................................................................62