Petrofacies and Paleotectonic Evolution of Gondwanan And
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PETROFACIES AND PALEOTECTONIC EVOLUTION OF GONDWANAN AND POST-GONDWANAN SEQUENCES OF NEPAL Except where reference is made to the work of others, the work described in this thesis is my own or was done in collaboration with my advisory committee. This thesis does notinclude proprietary or classified information. _____________________________________ Raju Prasad Sitaula Certificate of Approval: _____________________ _____________________ Charles E. Savrda Ashraf Uddin, Chair Professor Associate Professor Geology and Geography Geology and Geography _____________________ _____________________ Willis E. Hames George T. Flowers Professor Dean Geology and Geography Graduate School PETROFACIES AND PALEOTECTONIC EVOLUTION OFGONDWANAN AND POST-GONDWANAN SEQUENCES OF NEPAL Raju Prasad Sitaula A Thesis Submitted to the Graduate Faculty of Auburn University in Partial Fulfillment of the Requirement for the Degree of Master of Science Auburn, Alabama Auburn, Alabama December 18, 2009 PETROFACIES AND PALEOTECTONIC EVOLUTION OF GONDWANAN AND POST-GONDWANAN SEQUENCES OF NEPAL Raju Prasad Sitaula Permission is granted to Auburn University to make copies of this thesis at its discretion, upon the request of individuals or institutions and at their expense. The author reserves all publication rights. _____________________________ Raju Prasad Sitaula ___________________________ Date of Graduation iii VITA Raju Prasad Sitaula, son of Mr. Murari Prasad Sitaula and Mrs. Renuka Devi Sharma Sitaula, was born in 1979 in Bhadrutar, Nuwakot. He passed his school Leaving Certificate Examination in 1996 from Adarsha Yog Hari Madhyamik Vidhyalaya. He passed the Proficiency Certificate Level Examination in 1998 from Amrit Science College. He received his Bachelor of Science and Master of Science degrees in Geology in 2002 and 2005, respectively, from Tri-Chandra Multiple Campus and Tribhuvan University in Nepal. He entered the graduate school at Auburn University to pursue his second Masters degree from the Department of Geology and Geography in Fall 2007. iv THESIS ABSTRACT PETROFACIES AND PALEOTECTONIC EVOLUTION OF GONDWANAN AND POST-GONDWANAN SEQUENCES OF NEPAL Raju Prasad Sitaula Master of Science, December 18, 2009 (Bachelor of Science, Trichandra College, Nepal, 2004) (Master of Science, Tribhuvan University, Nepal, 2005) 206 Typed Pages Directed by Ashraf Uddin The Gondwanan sequences are widely distributed in several intracratonic basins of peninsular India and also as discontinuous patches along the Himalayan orogenic belt. The Tansen Group (2400 m) in western Nepal is thicker and more complete than the Katari (380 m) and the Barahachettra (350 m) groups located in eastern Nepal. In the Tansen Group, modal compositions of sandstone change from arkosic (Permo-Carboniferous unit) to quartz arenitic and then to litharenitic (Eocene-Early Miocene). Similar modal compositions are also present only in alleged Permo- Carboniferous units Katari and Barahachettra groups of eastern Nepal. The quartzofeldspathic sandstones of the Permo-Carboniferous Sisne (western Nepal) and Saptakoshi (eastern Nepal) formations show high Eu values. The Quartzite unit of the Saptakoshi Formation seems similar to the Amile Formation of western Nepal as both contain higher percentages of mature quartz and stable heavy minerals, and show similar v REE patterns. High contents of lithic fragments with relatively rare feldspars indicate that the Tamrang sandstones were deposited in the juvenile foreland basin between India and Tibet like the Eocene Bhainskati Formation of western Nepal. Garnet chemistry suggests sediment supply from variously graded metamorphic rocks. Tourmaline chemistry indicates sediments derivation from both lithium-high and lithium-low igneous rocks. Chrome-spinels with low TiO2 contents in the Taltung Formation show evidence of provenance from alkaline basalts. Cooling ages of detrital muscovites from the Permo-Carboniferous units of all three study sections show some older ages (300 Ma to 1700 Ma) and few younger (17 Ma to 25 Ma) ages. The older ages could be related to the magmatism in the Indian craton (e.g., Malani Rhyolite, Erinpura Granite, Chotanagpur Gneissic Terrain). Ages ~ 40 Ma muscovites from the Bhainskati Formation suggest a Himalayan orogenic source. Relatively younger ages, however, could indicate about the possible argon loss from the muscovite or misinterpretation of the stratigraphy. This study suggests that the stratigraphy of the Gondwana sequences in eastern Nepal needs to be re-evaluated. The existing quartzite unit of supposedly Permo- Carboniferous Saptakoshi Formation (eastern Nepal) should belong to Late Cretaceous, equivalent to the Amile Formation of western Nepal. The Tamrang Formation (eastern Nepal), which is currently considered as Permo-Carboniferous to Cretaceous, could be an equivalent unit of the Eocene Bhainskati Formation of western Nepal. vi ACKNOWLEDGEMENTS I would like to express my thanks and gratitude to my dear teacher Dr. Ashraf Uddin for bringing me to Auburn University and giving me the chance to get a Master’s degree in Geology. Dr. Uddin helped me not only as the principal advisor but also as a real guardian to get the best outcome of this research. I would like to express my sincere thanks to Dr. Charles Savrda, who helped with significant editing in this thesis. It would have been difficult to get this research work done without Dr. Savrda. I also would like to thank Dr. Willis Hames for help with the geochronology part of this research. I also acknowledge Mr. Chris Fleisher of University of Georgia for help during microprobe analysis. I thank Dr. Bishal Nath Upreti and Dr. Megh Raj Dhital for continuously guiding me through my research, supporting my fieldwork, and reviewing my thesis work. I want to thank my colleagues Pawan Budhathoki, Ashok Sigdel, and Biraj Gautam for their immense help in my fieldwork. I also want to pay my sincere thanks to Mr. Suryalal Shrestha who provided lodging support at Masyam, Palpa, during my fieldwork at the Tansen section. I am truly grateful to my colleagues at Auburn University, Subhadip Mandal and Shahadat Hossain, for their significant support throughout the development of thesis work, for literature review, lab work, data analysis vii and computer work. I am thankful for Subhadip not only for his support but also for the support I got from him while sharing an apartment. I am very grateful to Eva Lilly and Sheila Arington for their kind support throughout my study with all administrative work. John Simms always helped to solve the computer hardware problems I got during my work in the department. I also like to thank Dr. Zeki Billor for his moral support and proper guidance for muscovite separation. I also want to pay my sincere thanks to my seniors Prakash Dhakal and Mohammad Wahidur Rahman for their guidance. Prakash was the one who helped me to adjust with educational system and social life in United States. I am also grateful to Bibek Upreti for his support in my thesis work as well as in my daily life. It was Bibek who broke most of my sandstones samples which were very hard. This research was funded by the U.S National Science Foundation (NSF-EAR- 0310306), Geological Society of America, and the Department of Geology and Geography of Auburn University. I want to thank my parents who gave me the opportunity to see this wonderful world and supported me in every step of my life. I would like to thank my brother and sisters for their love and support. viii Style manual or journal used Geological Society of America Bulletin Computer software used Adobe Acrobat 6 Professional Adobe Illustrator 8.0 Adobe Photoshop CS 2 Macromedia FreeHand 11.0 Golden Software Grapher 3.0 Golden Software Surfer 8.0 Microsoft Excel 2007 Microsoft Word 2007 Microsoft Office Picture Manager 2007 ix TABLE OF CONTENTS Page LIST OF FIGURES xii LIST OF TABLES xx CHAPTER 1: INTRODUCTION………………………………………………....... 1 1.1 Introduction…………………………………………………………………….. 1 1.2 Location of the study area……………………………………………..……….. 4 1.3 Previous Works………………………………………………………………… 5 1.4 Objectives………………………………………………………………………. 7 CHAPTER 2: GONDWANAN SEQUENCES OF NEPAL HIMALAYA AND PENINSULAR INDIA……………………………………………………………... 8 2.1 General Geological Setting of Nepal Himalaya………………………………... 8 2.2 Gondwana Stratigraphy of Nepal………………………………………………. 10 2.3 Gondwanan Sequences in other parts of Nepal………………………………… 24 2.4 Distribution of Gondwanan Basins in Peninsular India………………………... 26 2.5 Gondwanan Stratigraphy of other parts of extra-Peninsular India and other parts of Gondwanaland……………………………………………………………... 31 CHAPTER 3: EVOLUTION OF GONDWANAN BASINS……………………… 36 3.1 Continental Breakup of Gondwanaland………………………………………... 36 3.2 Evolution of the Passive Margin at the Northern Boundary of India…………... 38 3.3 Evolution of Facies and Climatic control during the Evolution of Gondwanan Sequences…………………………………………………………………………... 40 CHAPTER 4: SANDSTONE PETROGRAPHY…………………………………... 44 4.1 Introduction…………………………………………………………………….. 44 4.2 Methods………………………………………………………………………… 45 4.3 Petrography……………………………………………………………………... 47 4.4 Sandstone Modes……………………………………………………………….. 60 4.5 Petrofacies Evolution …………………………………………………………... 62 x CHAPTER 5: HEAVY MINERAL ANALYSIS…………………………………... 68 5.1 Introduction……………………………………………………….……………. 68 5.2 Methods………………………………………………………………………… 71 5.3 Results………………………………………………………………………….. 74 5.4 Provenance……………………………………………………………………... 82 CHAPTER 6: MICROPOBE ANALYSIS…………………………………………. 86 6.1 Introduction…………………………………………………………………….