Structural Evolution Of The Central Nepal Fold Thrust Belt And Regional Tectonic And Structural Significance Of The Ramgarh Thrust Phd
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Structural Evolution Of The Central Nepal Fold Thrust Belt And Regional Tectonic And Structural Significance Of The Ramgarh Thrust Phd
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Author : Ofori Pearson
language : en
Publisher:
Release Date : 2002
Structural Evolution Of The Central Nepal Fold Thrust Belt And Regional Tectonic And Structural Significance Of The Ramgarh Thrust Phd written by Ofori Pearson and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with categories.
Structural And Thermal Evolution Of The Himalayan Thrust Belt In Midwestern Nepal
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Author : P.G. DeCelles
language : en
Publisher: Geological Society of America
Release Date : 2020-06-16
Structural And Thermal Evolution Of The Himalayan Thrust Belt In Midwestern Nepal written by P.G. DeCelles and has been published by Geological Society of America this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-06-16 with Science categories.
"Spanning eight kilometers of topographic relief, the Himalayan fold-thrust belt in Nepal has accommodated more than 700 km of Cenozoic convergence between the Indian subcontinent and Asia. Rapid tectonic shortening and erosion in a monsoonal climate have exhumed greenschist to upper amphibolite facies rocks along with unmetamorphosed rocks, including a 5-6-km-thick Cenozoic foreland basin sequence. This Special Paper presents new geochronology, multisystem thermochronology, structural geology, and geological mapping of an approximately 37,000 km2 region in midwestern and western Nepal. This work informs enduring Himalayan debates, including how and where to map the Main Central thrust, the geometry of the seismically active basal Himalayan detachment, processes of tectonic shortening in the context of postcollisional India-Asia convergence, and long-term geodynamics of the orogenic wedge"--Publisher's website
Tectonics Of The Himalaya
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Author : S. Mukherjee
language : en
Publisher: Geological Society of London
Release Date : 2015-09-28
Tectonics Of The Himalaya written by S. Mukherjee and has been published by Geological Society of London this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-09-28 with Science categories.
The Himalayan mountain belt, which developed during the India–Asia collision starting about 55 Ma ago, is a dramatically active orogen and it is regarded as the classic collisional orogen. It is characterized by an impressively continuous 2500 km of tectonic units, thrusts and normal faults, as well as large volumes of high-grade metamorphic rocks and granites exposed at the surface. This constitutes an invaluable field laboratory, where amazing crustal sections can be observed directly in very deep gorges. It is possible to unravel the tectonic and metamorphic evolution of litho-units, to observe the mechanisms of exhumation of deep-seated rocks and the propagation of the deformation. Himalayan tectonics has been the target of many studies from numerous international researchers over the years. In the last 15 years there has been an explosion of data and theories from both geological and geophysical perspectives. This book presents the results of integrated multidisciplinary studies, including geology, petrology, magmatism, geochemistry, geochronology and geophysics, of the structures and processes affecting the continental lithosphere. These processes and their spatial and temporal evolution have major consequences on the geometry and kinematics of the India–Eurasia collision zone.
Channel Flow Ductile Extrusion And Exhumation In Continental Collision Zones
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Author : Richard D. Law
language : en
Publisher: Geological Society of London
Release Date : 2006
Channel Flow Ductile Extrusion And Exhumation In Continental Collision Zones written by Richard D. Law and has been published by Geological Society of London this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Science categories.
This volume includes sections on: Evolution of ideas on channel flow and ductile extrusion in the Himalaya-Tibetan Plateau system; Modeling channel flow and ductile extrusion processes; Geological constraints on channel flow and ductile extrusion as an important orogenic process in the Himalaya-Tibetan Plateau, the Hellenides and Appalachians, and the Canadian Cordillera.
Himalayan Tectonics
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Author : P.J. Treloar
language : en
Publisher: Geological Society of London
Release Date : 2019-10-08
Himalayan Tectonics written by P.J. Treloar and has been published by Geological Society of London this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-10-08 with Science categories.
The Himalaya–Karakoram–Tibet mountain belt resulted from Cenozoic collision of India and Asia and is frequently used as the type example of a continental collision orogenic belt. The last quarter of a century has seen the publication of a remarkably detailed dataset relevant to the evolution of this belt. Detailed fieldwork backed up by state-of-the-art structural analysis, geochemistry, mineral chemistry, igneous and metamorphic petrology, isotope chemistry, sedimentology and geophysics produced a wide-ranging archive of data-rich scientific papers. The rationale for this book is to provide a coherent overview of these datasets in addressing the evolution of the mountain ranges we see today. This volume comprises 21 specially invited review papers on the Himalaya, Kohistan arc, Tibet, the Karakoram and Pamir ranges. These papers span the history of Himalayan research, chronology of the collision, stratigraphy, magmatic and metamorphic processes, structural geology and tectonics, seismicity, geophysics, and the evolution of the Indian monsoon. This landmark set of papers should underpin the next 25 years of Himalayan research.
Structural Evolution Of The Himalayan Thrust Belt West Nepal
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Author : An Li
language : en
Publisher:
Release Date : 2013
Structural Evolution Of The Himalayan Thrust Belt West Nepal written by An Li and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Geology categories.
Himalayan foreland basin strata were recently documented to crop out in a structural window in the central portion of the Himalayan thrust belt. Presently, structural interpretations of the thrust belt do not explain in detail how these strata were incorporated into the thrust belt and why they are not widely exposed throughout the Himalaya. My research provides answers to these two issues. The structural window is located in the Lesser Himalaya of western Nepal and exposes rocks which lie structurally beneath the Main Central thrust (MCT) and Ramgarh thrust (RT) sheets. The thrust sheet consists of Proterozoic metamorphic rocks. Below the thrust sheet, footwall rocks exposed in the window are unmetamorphosed sedimentary rocks which consist of the early foreland basin strata (the Suntar and Swat formations) and the pre-foreland basin strata (the Melpani and Lakharpata formations). These unmetamorphosed rocks are present in the foreland basin beneath Siwalik group, ~100km to the south (towards the foreland). Two geologic maps were created; One covering the structural window and another covering the thrust belt from the High Himalaya to the MFT (Main Frontal Thrust). Several cross-sections were constructed from both maps. Structural reconstruction of these cross-sections reveal the following: 1) ~ 75 km-long hanging wall flat extends northward from its surface trace to the southern margin of the Lesser Himalayan duplex; 2) The geometry of the Jarjarkot klippe is narrower and structurally deeper than klippe to the west. The geometry of the northern flank of the klippe results from stacking of duplex horses, while the geometry of the southern flank results from slip over a ramp in the footwall of the MBT, 3) The early foreland basin strata in the window are modeled to have originated at the front of the thrust belt, and subsequently buried by the Ramgarh and MCT thrust sheets, and 4) Exposure of these strata results from growth of the duplex which brought them to a higher structural level than most parts of the thrust belt. This structural model explains why the only other exposure of foreland basin strata within the thrust belt is documented within a duplex on the north side of the Dadeldhura klippe. Moreover, this model predicts that foreland basin strata are likely to be exposed wherever duplexes exist.
Structural And Kinematic Evolution Of The Himalayan Thrust Belt Central Nepal
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Author : Subodha Khanal
language : en
Publisher:
Release Date : 2014
Structural And Kinematic Evolution Of The Himalayan Thrust Belt Central Nepal written by Subodha Khanal and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Electronic dissertations categories.
Over the last two decades, several competing dynamic models have been proposed to explain the kinematics of the Himalayan thrust belt. The accuracy of dynamic and kinematic models is limited by poorly documented geologic structures. With increased accessibility of the thrust belt and advances in analytical techniques, several new data sets greatly improve our understanding and provide a background to reevaluate the kinematics of the Himalayan thrust belt. In this dissertation, I integrate structural mapping, microstructural analysis, detrital and igneous zircon geochronology, low-temperature thermochronology, Nd isotopic analysis, and structural reconstructions in central Nepal to determine the evolution of the Himalayan thrust belt. Because the role and evolution of the Main Central thrust, the Ramgarh-Munsiari thrust, and the Lesser Himalayan duplex are highly debated, I emphasize these systems to provide a comprehensive structural evolution of the Himalayan thrust belt. U-Pb dating of metamorphic rims of igneous zircons and crystallization ages of cross-cutting pegmatite veins suggest that deformation on the Himalayan thrust belt started with slip on an intra-Greater Himalayan thrust active at ~20-29 Ma that emplaced the now erosionally isolated Kathmandu klippe. These ages predate the slip on the Main Central thrust. Absence of a fault contact between the Greater Himalaya and Tethyan Himalaya in the klippe suggests the South Tibetan Detachment system may have activated after the slip started on the intra-Greater Himalayan thrust. Ductile motion on the South Tibetan Detachment system may have ended prior to the activation of the Main Central thrust. This result and observations contradict the extrusion model that advocates contemporaneous activity with thrust sense shear on the Main Central thrust and normal sense shear on the South Tibetan Detachment system. In addition, there is another orogenic scale thrust, subparallel to the Main Central thrust, the Ramgarh-Munsiari thrust, that only carries lower Lesser Himalayan Paleoproterozoic rock over other Lesser Himalayan rock and accommodates a magnitude of shortening similar to the 100's km of slip on the Main Central thrust. I construct an orogenic scale balanced cross-section along the Marsyangdi River where the entire Lesser Himalayan duplex is exposed, particularly focusing on the architecture of the duplex to determine whether the duplex is forward dipping or hinterland dipping and the presence/absence of an orogenic scale, out-of-sequence thrust. I integrate quartz-feldspar deformation temperatures and zircon (U-Th)/He thermochronology and present a kinematic model that provides the structural context for geophysical, petrological, and geochronological studies in central Nepal. Collectively, this study helps to determine partitioning of strain among the various thrust sheets that account for over 2000 km of shortening in a compressional continental tectonic setting. The results suggest that deformation in the Himalaya began with the activation of an intra-Greater Himalayan thrust and successively moved south with the activation of Main Central thrust, Ramgarh-Munsairi thrust, Lesser Himalayan duplex, and finally the Subhimalayan thrust system. Although there was minor out-of-sequence thrusting in the hinterland, the bulk of the Himalaya evolved in-sequence thrusting from north to south.
Upper Crustal Shortening And Forward Modeling Of The Himalayan Fold Thrust Belt Along The Budhi Gandaki River Central Nepal
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Author : Subodha Khanal
language : en
Publisher:
Release Date : 2009
Upper Crustal Shortening And Forward Modeling Of The Himalayan Fold Thrust Belt Along The Budhi Gandaki River Central Nepal written by Subodha Khanal and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Electronic dissertations categories.
Geologic mapping along the Budhi-Gandaki River in central Nepal reveals 6 significant structures: 1) South Tibetan Detachment system; 2) Main Central thrust; 3) Ramgarh thrust; 4) Lesser Himalayan duplex including the Trishuli thrust; 5) Main Boundary thrust; and 6) Main Frontal thrust system. A balanced cross-section between the South Tibetan Detachment system and Main Frontal thrust reveals that the region has a minimum total shortening of 76% or 420 km. The breakdown of the accommodation of shortening on each thrust is as follows: Main Central thrust - 115 km; Ramgarh thrust - 120 km; Lesser Himalayan duplex including the Trishuli thrust - 156 km; Main Boundary thrust - 10 km; Main Frontal thrust system - 19 km. In order to validate the balanced cross-section, a reconstruction program was used to forward model the system. By moving faults with appropriate amounts of displacement over a reasonable configuration of undeformed stratigraphy from the hinterland to foreland, the deformation of the Himalayan thrust belt along the Budhi-Gandaki River cross-section is reproduced. The forward modeling program moves hanging wall rock over stationary footwall rock using each individual fault identified in the balanced crosssection. Hanging wall rock deforms as it is thrust over footwall structures. Using forward modeling, the cross-section has a shortening estimate of 412 km or 75%. The two shortening estimates are virtually identical indicating the balanced cross-section along the Budi-Gandaki River is viable and admissible.
Structural Evolution Of Thakkhola Graben
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Author : Thomas Baltz
language : en
Publisher:
Release Date : 2012
Structural Evolution Of Thakkhola Graben written by Thomas Baltz and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Geology categories.
The Thakkhola Graben of central Nepal is one of several north-south-trending rifts and grabens throughout the Himalayan hinterland and southern Tibet. The faults bounding the graben run from the crest of the Himalayas at the Annapurna and Dhaulagiri Ranges to the suture between India and Asia. This suture is reported to separate two disparate stress regimes, arc-perpendicular compression in the Nepal Himalayas to the south and arc-parallel extension in the Tibetan Plateau to the north. However, two lines of evidence suggest the India-Asia Suture no longer functions as a structural boundary between these stress fields: (1) the Lopukangri Rift cuts and offsets the suture, and (2) the Thakkhola Graben is located south of the suture. Despite decades of research in the Thakkhola Graben, an accurate account of fault geometry and kinematics has yet to be presented. Therefore its relationship to extensional structures in Tibet and its role in Himalayan tectonics is undetermined. Field mapping, combined with kinematic modeling and reconstruction of offset piercing points, has confined the geometry and kinematics of the faults bounding the Thakkhola Graben. The western boundary of the graben is the Dangardzang Fault and the eastern boundary is the Muktinath Fault, both of which are steeply dipping and cut down into the middle crust. The Dangardzang Fault consists of two parallel fault strands, with the easternmost accommodating the majority of strain. This fault has accommodated 4.5 kilometers of dip-slip displacement, 5.3 kilometers of dextral strike-slip displacement, and 1.4 kilometers of horizontal extension. The Muktinath Fault consists of one dominant fault strand with several subsidiary faults of lesser magnitude. This fault has accommodated 4.2 kilometers of dip-slip displacement, 1.9 kilometers of sinistral strike-slip displacement, and 0.8 kilometers of horizontal extension. Comparison of the Thakkhola Graben with the Lopukangri Rift to the north shows both of these structures share similar fault geometries, magnitudes of slip, and kinematics. This relationship implies the same stress field is active on both sides of the India-Asia Suture and therefore, in this region it no longer operates as a structural boundary between the Himalayas and Tibet.
Dissertation Abstracts International
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Author :
language : en
Publisher:
Release Date : 2003
Dissertation Abstracts International written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Dissertations, Academic categories.