Louisiana State University LSU Digital Commons LSU Doctoral Dissertations Graduate School 2014 Contractional Tectonics: Investigations of Ongoing Construction of the Himalaya Fold-thrust Belt and the Trishear Model of Fault-propagation Folding Hongjiao Yu Louisiana State University and Agricultural and Mechanical College, [email protected] Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_dissertations Part of the Earth Sciences Commons Recommended Citation Yu, Hongjiao, "Contractional Tectonics: Investigations of Ongoing Construction of the Himalaya Fold-thrust Belt and the Trishear Model of Fault-propagation Folding" (2014). LSU Doctoral Dissertations. 2683. https://digitalcommons.lsu.edu/gradschool_dissertations/2683 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 Doctoral Dissertations by an authorized graduate school editor of LSU Digital Commons. For more information, please [email protected]. CONTRACTIONAL TECTONICS: INVESTIGATIONS OF ONGOING CONSTRUCTION OF THE HIMALAYAN FOLD-THRUST BELT AND THE TRISHEAR MODEL OF FAULT-PROPAGATION FOLDING 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 Hongjiao Yu B.S., China University of Petroleum, 2006 M.S., Peking University, 2009 August 2014 ACKNOWLEDGMENTS I have had a wonderful five-year adventure in the Department of Geology and Geophysics at Louisiana State University. I owe a lot of gratitude to many people and I would not have been able to complete my PhD research without the support and help from them. This dissertation is dedicated to my advisor, Dr. Alex Webb, who set priorities and motivation for my graduate studies. His constant encouragement, guidance, advice, enthusiasm to geology, and rigorous requirements have inspired me to make progress and helped me complete my thesis work with happiness and tears. I also appreciate the support and inspiration I've received from my committee members and other faculty at LSU: Dr. Gary Byerly, Dr. Barb Dutrow, Dr. Darrell Henry, and Dr. Peter Clift for their generous time and effort in guiding and reviewing my Ph.D. work. The thermochronologic data in this dissertation was conducted in Geologie, Technische Universitat Bergakademie Freiberg in Germany for about 9 months. I am grateful to Dr. Raymond jonckheere for his insight and patience to advance my knowledge of Fission track technique. I benefited a lot from discussion with Dr. Lothar Ratschbacher and I also want to thank him for arranging my trip in Germany. I extend my thankfulness to Bastian Wauschkuhn, Yang Zhao for their helpful advice on fission track sample preparation and data analysis. I would like to thank Dr. Kyle Larson for analyzing quartz c-axis fabrics, Rick Young for making thin sections, and Kyle Barber for rock cutting. I want to extend my appreciation to my fellow graduate students Dennis Donaldson, Cindy Colόn, and Chase Billeaudeau in the Structural Geology group. Their helps and discussions have been always encouraging me to move forward. ii Finally, I would like to express my gratefulness to my Husband Dian He and my parents in law. I owe a great debt of gratitude to my parents. Without their sacrifices and support, I would have not even started this journey abroad yet. The Himalayan research was supported by the start-up grant from Louisiana State University and the Louisiana Board of Regents grant to Dr. Webb, the AAPG and GSA graduate student research grants to Hongjiao Yu. The Uncompahgre Uplift research is my intern project in Shell Oil Company. I would like to thank J.P. Brandenburg, David Wolf, Steve Naruk, David Kirschner, and Michael Gross for their guidance and discussions when I was interning at Shell. iii TABLE OF CONTENTS ACKNOWLEDGMENTS…………………………………………………………………...……ii ABSTRACT………………………………………………..…………………………………….vi CHAPTER 1 INTRODUCTION…………………………………………………………………..…………….1 1.1 The Himalayan Fold-thrust Belt ………..………………………………………………….1 1.2 The Uncompahgre Uplift …..………………………………………………………………3 CHAPTER 2 EXTRUSION VERSUS DUPLEXING MODELS OF HIMALAYAN MOUNTAIN BUILDING: DISCOVERY OF THE PABBAR THRUST, NW INDIAN HIMALAYA …………...........……5 2.1 Introduction…………………………………………………………………….…...………5 2.2 Geology of the Northwest Indian Himalaya ……………………………………………...11 2.2.1 Stratigraphic Diversity……….………………………………….……………………12 2.2.2 Tectonic framework....……………………..…………………………….…………...14 2.3 Methods……………………………………………………………………………………17 2.3.1 Field Mapping………………………………………………..……………………….17 2.3.2 Microstructural Analysis ………………...……………………….…………………..17 2.4 Results of Structural Geology Mapping ……...…………………………………………..18 2.4.1 Field Observations …………………………………………………………………...21 2.4.1.1 Tharoch Transect.………………………………..………………………………21 2.4.1.2 Lower Pabbar Transect …………………..……......…………………………….26 2.4.1.3 Tons River Transect…..…..……………………………………………….……..28 2.4.2 Quartz Microstructures ………………………………….………………...…………30 2.5 Discussion …………………………………...……………………………………………31 2.5.1 Kinematic Evolution of the Tons Thrust, Pabbar Thrust and Berinag Thrust……......32 2.5.2 Along-strike Variations of Thrust Geometries and Stratigraphic Correlation…...…...33 2.6 Conclusions………………………………………………………………………………..38 CHAPTER 3 KINEMATIC EVOLUTION OF HIMALAYAN OROGEN CONSTRAINED BY NEW FISSION TRACK ANALYSIS IN NW INDIA…..…………………………….……………….41 3.1 Introduction……………………………………………………………………………......41 3.2 Methods: Apatite and Zircon Fission Track Analysis………….…………………………42 3.3 Results………………………………………………………………………………..........46 3.3.1 Fission Track Analysis…………………………………………………………..........46 3.3.2 Interpretation…….………….…………………………………………………….......49 3.4 Balanced Palinspastic Reconstruction Across the NW Indian Himalaya…………………51 3.4.1 Restoration ca. 28 Ma……………..……………………………………………….....54 3.4.2 Restoration ca. 20 Ma……………..……………………………………………….....54 3.4.3 Restoration ca. 13 Ma……………..……………………………………………….....54 3.4.4 Restoration ca. 8.1 Ma…………….……………………………………………….....55 3.4.5 Restoration ca. 5.2 Ma…………….……………………………………………….....55 iv 3.5 Discussion: Extrusion vs. Duplexing Models of Himalayan Mountain Building……...…56 3.6 Conclusions……...….……………………………………………………………………..58 CHAPTER 4 KINEMATIC TRISHEAR MODEL OF FAULT-PROPAGATION FOLDING TO PREDICT DEFORMATION BANDS, COLORADO NATIONAL MONUMENT, NW UNCOMPAHGRE UPLIFT, USA……………………………………………………………………………………59 4.1 Introduction………………………………………………………………………………..59 4.2 Geology Background……….…...……………………………………………………..….62 4.2.1 Tectonic History of the Uncompahgre Uplift………………………………………...62 4.2.2 Major Stratigraphy…...…………...…………………………………………………..65 4.2.3 Major Faults in CNM, Uncompahgre Uplift…….……………………………………66 4.3 Methods and Data……………………………………………………………………..67 4.3.1 Method: Kinematic Trishear Model of Fault-propagation Folding……………...…...67 4.3.2 Data: Characteristics of Deformation Bands in CNM………..………………………68 4.4 Results……………………………..……………………………………………………....69 4.4.1 Balance Reconstruction………….………………….……………………………......69 4.4.1.1 Cross Section Reconstruction along the East Kodels Canyon...………..………..70 4.4.1.2 Cross Section Reconstruction along the North Canyon…..…………..………..71 4.4.1.3 Cross Section Reconstruction along the East Canyon…..…………….………..71 4.4.2 Strain Calculation………...……………………………..…………………….……....75 4.5 Discussion………….…………...…………………………………………………………77 4.6 Conclusions……………………………………………………………………..…………79 CHAPTER 5 SUMMARY AND CONCLUSIONS………..…………………………………………………..81 5.1 Growth of the Himalayan Fold-thrust belt Dominated Duplexing Processes…...….……..81 5.2 Kinematic Trishear Fault-propagation Folding Model to Predict Deformation Bands…...83 REFERENCES………..………………………………………………………………………....85 APPENDIX A: APATITE FISSSION TRACK DATA.……………………………………………...…………108 APPENDIX B: ZIRCON FISSSION TRACK DATA...……………………………………………...…………114 PLATE 1: SEQUENTIAL CROSS-SECTION RESTORATION ACROSS THE NW INDIAN HIMALAYA………………………….……………………………………………...…………127 VITA……………………………………………………………………………………………128 v ABSTRACT This dissertation focuses on the kinematic evolution of contractional tectonics: the Himalayan fold-thrust belt along the collisional orogenic belts, and growth of the basement- cored monoclines in Colorado Plateau. Ongoing Himalayan growth is generally thought to be dominated by duplexing and/or extrusion processes. Duplexing models highlight accretion of material from the subducting plate to the over-riding orogenic wedge, whereas extrusion models focus on up-dip translation of a block bounded by out-of-sequence faults. Here, a primary outstanding question involves the uncertain relationship of the Berinag thrust and the Tons thrust, structures with displacements of >80 km and >40 km, respectively. The uncertainty allows the complete range of duplexing and extrusion processes for the integrated kinematic history since the Middle Miocene. To address this issue, field mapping, kinematic analysis, and analysis of quartz recrystallization textures were performed. Our results reveal a new discovery: a ~ 450 m thick top-to-southwest shear zone, termed the Pabbar thrust. The Pabbar thrust placed the Outer Lesser Himalayan Sequence (the Tons thrust hanging wall) directly on the Berinag Group (the Berinag thrust hanging wall). This discovery requires that the Pabbar thrust developed first, followed by footwall accretion of the Berinag-Tons thrust sheet, operating as a single structure.