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Magnetostratigraphy, Topography and Geology of the Nepal

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Magnetostratigraphy, Topography and Geology of the Nepal MAGNETOSTRATIGRAPHY, TOPOGRAPHY AND GEOLOGY OF THE NEPAL HIMALAYA: A GIS AND PALEOMAGNETIC APPROACH by Tank Prasad Ojha _________________________ A Dissertation Submitted to the Faculty of the DEPARTMENT OF GEOSCIENCES In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 2009 2 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE As members of the Dissertation Committee, we certify that we have read the dissertation prepared by Tank Prasad Ojha entitled Magnetostratigraphy, Topography and Geology of the Nepal Himalaya: A GIS and Paleomagnetic Approach and recommend that it be accepted as fulfilling the dissertation requirement for the Degree of Doctor of Philosophy ______________________________________________ Date: April 27, 2009 Peter G. DeCelles ______________________________________________ Date: April 27, 2009 Jay Quade ______________________________________________ Date: April 27, 2009 Craig Wissler ______________________________________________ Date: April 27, 2009 George E. Gehrels ______________________________________________ Date: April 27, 2009 Paul Kapp Final approval and acceptance of this dissertation is contingent upon the candidate’s submission of the final copies of the dissertation to the Graduate College. I hereby certify that I have read this dissertation prepared under my direction and recommend that it be accepted as fulfilling the dissertation requirement. ______________________________________________ Date: April 27, 2009 Dissertation Director: Peter G. DeCelles 3 STATEMENT BY AUTHOR This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at the University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this dissertation are allowable without special permission, provided that accurate acknowledgement of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the dean of the Graduate College when in his or her judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author. SIGNED: Tank Prasad Ojha 4 ACKNOWLEDGEMENTS I am extremely grateful to my primary advisors Professor Peter DeCelles and Professor Jay Quade for this achievement. Without their inspiration, moral and financial support it would have been impossible to conduct a thorough paleomagnetic research and GIS database development of Nepal Himalayas. This journey began in early1989 when I met Professor Quade in the remote Nepalese Siwaliks to work on a contract job. Gradually mutual research interest grew between us Professor Quade returned to Nepal frequently for more geological field work. During his third visit to Nepal in 1994 he was accompanied by Professor DeCelles and introduced me to him. Professor DeCelles encouraged me to join the University of Arizona as a graduate student and the same year I entered the Department of Geosciences as an MS student. For over five years I was most fortunate to carry the magnetostratigraphic research in Mio-Pliocene Siwalik Group sediments and the late Oligocene to early Miocene Dumri Formations under the supervision of Professor Robert F. Butler. While being affiliated with Department of Geosciences at U of A for past 12 years as staff and student my commitment to Himalayan geological research continued growing from extensive magnetostratigraphic study of foreland basin sediments to mapping of Lesser Himalayan and greater Himalayan rocks. In early 2004 Professor George Gehrels advised me to compile a GIS based new geological map of Nepal; with his continuous encouragement I ended up developing a GIS based geological and topographical database for Nepal. This effort paves a new path for Nepalese Planners, Engineers and Geologists to develop the country better. Drs. Peter DeCelles, Jay Quade and George Gehrels allowed me the full freedom to pursue my research. They were happy and patient while I spent years on conducting magnetostratigraphic research in foreland basin sediments and developing the geological and topographical GIS database. Because of this freedom I have had great opportunities to conduct a multidisciplinary research in Nepal Himalayas. Without Robert F. Butler’s support and teaching the magnetostratigraphic research of Sub-Himalayan zone of Nepal was not possible. He allowed me full freedom to use his laboratory and resources. Dr. Paul Kapp allowed unlimited access to his geostructure laboratory to scan over 700 topographic and geological maps of Nepal for manual digitization. Dr. Craig Wissler helped me to understand all my results derived from the manual digitization of topographic maps and how to use these results for various spatial analyses. I am deeply grateful for the interaction that I have had with Professor George Davis of the Department of Geosciences and Professor Phil Guirtin at the school of Renewable Natural Resources. Financial support for this research was provided by the Department of Geosciences at the University of Arizona, the National Geographic Society, ExxonMobil Exploration Company, and the U. S. National Science Foundation. Himalayan Experience Kathmandu, Nepal provided logistic support for field work and the manual digitization of topographic maps in their Kathmandu office. Last but not least I am deeply grateful to my wife Rama for this achievement. Her loving support and endless patience made this multidisciplinary research to happen. 5 DEDICATION To my wife Rama, for her love, courage, and patience, and to the village people of far west Nepal 6 TABLE OF CONTENTS LIST OF FIGURES……………………………………………………………………..9 LIST OF TABLES…………………………………………………………………….. 13 ABSTRACT……………………………………………………………………………. 14 CHAPTER 1: INTRODUCTION……………………………………………………., 16 CHAPTER 2: MAGNETIC POLARITY STRATIGRAPHY OF THE NEOGENE SIWALIK GROUP AND DUMRI FORMATION, NEPAL………….. 22 ABSTRACT…………………………………………………………………………….. 22 INTRODUCTION…………………………………………………………………… … 23 GEOLOGICAL SETTING……………………………………………………………... 25 SAMPLING AND LABORATORY METHODS……………………………………… 30 CARBON ISOTOPE RESULTS FROM SIWALIK GROUP STRATA………………. 32 PALEOMAGNETISM OF SWAT KHOLA DEPOSITS……………………………… 33 PALEOMAGNETISM OF SURAI KHOLA DEPOSITS……………………………… 35 PALEOMAGNETISM OF TINAU KHOLA DEPOSITS……………………………... 38 PALEOMAGNETISM OF MUKSAR KHOLA DEPOSITS………………………….. 40 DISCUSSION…………………………………………………………………………... 42 Regional Correlations and Lithostratigraphic Patterns…………………………… … 42 Sediment Accumulation History……………………………………………………. 44 CONCLUSIONS……………………………………………………………………….. 48 CHAPTER 3: GIS DATABASE DEVELOPMENT FOR NEW GEOLOGICAL MAP OF NEPAL…………………………………………………… 77 ABSTRACT…………………………………………………………………………….. 77 INTRODUCTION……………………………………………………………………… 78 STUDY AREA…………………………………………………………………………. 81 OBJECTIVES…………………………………………………………………………... 82 DATA SOURCE………………………………………………………………………... 83 METHODS……………………………………………………………………………... 84 Scanning and Image Enhancement………………………………………………….. 85 Geo-Rectification……………………………………………………………………. 86 Onscreen Digitization of Topographic and Geologic Features……………………... 87 Features Editing and Merging……………………………………………………… . 88 DATA ANALYSIS AND VISUALIZATION…………………………………………. 89 Triangulated Irregular Network (TIN) Generation from Contour Interpolation……………………………………………… 89 Digital Terrain Model (DTM) Creation from TIN………………………………….. 90 Hillshade Generation from TINGRID………………………………………………. 92 7 TABLE OF CONTENTS – Continued Slope Map Generation from TINGRID and their Use…..……………………… .. ... 95 OVERLAY AND VISUALIZATION IN ARCMAP………………………………...... 97 REMOTE SURFACE MAPPING IN ARCMAP………………………………… .. … . 98 OVERLAY AND VISUALIZATION IN ARCSCENE…………………………… .. .. 100 CONCLUSIONS……………………………………………………………………… 102 CHAPTER 4: ROLE OF GEOGRAPHIC INFORMATION SYSTEM (GIS) IN GEOLOGICAL DATA STORAGE AND MAP MAKING: A CASE STUDY FROM FAR WEST NEPAL………………………………………..157 ABSTRACT…………………………………………………………………………... 157 INTRODUCTION…………………………………………………………………….. 159 WHY THE HIMALAYA……………………………………………………………. .. 160 REGIONAL GEOLOGICAL SETTING OF FAR WEST NEPAL HIMALAYAS………………………………………………………. 160 TECTONOSTRATIGRAPHY………………………………………………………. .. 161 Sub Himalayan Zone………………………………………………………………… 162 Lesser Himalayan Zone……………………………………………………………... 163 Kushma Formation………………………………………………………………… 164 Ranimata Formation………………………………………………………………. 164 Sangram Formation………………………………………………………………... 165 Galyang Formation………………………………………………………………… 165 Syangja Formation……………………………………………………………….....166 Lakharpata Group…………………………………………………………………. 166 Gondwana Unit…………………………………………………………………….. 167 Cenozoic Units……………………………………………………………………... 167 Greater Himalayan Zone……………………………………………………………..... 168 Tethyan Himalayan Zone……………………………………………………………... 169 REGIONAL STRUCTURES…………………………………………………………. 169 Himalayan Frontal Thrust or Main Frontal Thrust (HFT/MFT) System……………………………………………….. 169 Main Boundary Thrust System…………………………………………………….. 170 Ramgarh Thrust System………………………………………………………… .. .. 170 Dadeldhura Thrust System……………………………………………………… .. .. 171 Lesser Himalayan Duplex Zone……………………………………………………. 171 Main Central Thrust Zone………………………………………………………….. 172 GIS BASED CONCEPTUAL GEOLOGICAL DATA MODEL FOR SYNTHESIZED GEOLOGICAL MAP OF FAR WEST NEPAL………………….. .. 172 Coordinate System and Map Projection……………………………………………... 174 GIS Data Layer (Coverage)………………………………………………………….
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