Seismotectonics of the Himalayan Collision Zone: Geometry of the underthrusting Indian Plate beneath the Himalaya

1984 ◽  
Vol 89 (B2) ◽  
pp. 1147-1163 ◽  
Author(s):  
James Ni ◽  
Muawia Barazangi
Keyword(s):  
Indian Plate ◽  
Collision Zone ◽  
The Himalaya

Geological signatures of slab shear-off during ongoing India-Asia convergence

2021 ◽  
Author(s):  
Abdul Qayyum ◽  
Nalan Lom ◽  
Eldert L Advokaat ◽  
Wim Spakman ◽  
Douwe J.J van Hinsbergen
Keyword(s):  
Numerical Models ◽  
Leading Edge ◽  
Plate Motion ◽  
Indian Plate ◽  
Mantle Structure ◽  
Continental Lithosphere ◽  
Common View ◽  
Plate Convergence ◽  
Collision Zone ◽  
The Himalaya

<p>Much of our understanding of the dynamics of slab break-off and its geological signatures rely on numerical models with a simplified set-up, in which slab break-off follows arrival of a continent in a mantle-stationary trench, the subsequent arrest of plate convergence, and after a delay time of 10 Ma or more, slab break off under the influence of slab pull. However, geological reconstructions show that plate tectonic reality deviates from this setup: post-collisional convergence is common, trenches are generally not stationary relative to mantle, neither before nor after collision, and there are many examples in which the mantle structure below collision zones is characterized by more, or fewer slabs than collisions.</p><p>A key example of the former is the India-Asia collision zone, where the mantle below India hosts two major, despite the common view of a single collision. Kinematic reconstructions reveal that post-collisional convergence amounted 1000s of kms, and was associated with ~1000 km of trench/collision zone advance. Collision between India-Asia collision zone may provide a good case study to determine the result of post-collisional convergence and absolute lower and upper plate motion on mantle structure, and to evaluate to what extent commonly assumed diagnostic geological phenomena of slab break-off apply.</p><p>In addition to the previously identified major India, Himalaya, and Burma slabs, we here map smaller slabs below Afghanistan and the Himalaya that reveal the latest phases of break-off. We show that west-dipping and east-dipping slabs west and east of India, respectively, are dragged northward parallel to the slab, slabs subducting north of India are overturned, and that the shallowest slab fragments are found in the location where the horizontally underthrust Indian lithosphere below Tibet is narrowest. Our results confirm that northward Indian absolute plate motion continued during two episodes of break-off of large (>1000 km wide) slabs, and decoupling of several smaller fragments. These slabs are currently found south of the present day trench locations. The slabs are located even farther south (>1000 km) of the leading edge of the Indian continental lithosphere, currently underthrust below Tibet, from which the slabs detached, signalling ongoing absolute Indian plate motion. We conclude that the multiple slab break-off events in this setting of ongoing plate convergence and trench advance is better explained by shearing off of slabs from the downgoing plate, possibly at a depth corresponding to the base of the Indian continental lithosphere, are not (necessarily) related to the timing of collision. A recently proposed, detailed diachronous record of deformation, uplift, and oroclinal bending in the Himalaya that was liked to slab break-off fits well with our kinematically reconstructed timing of the last slab shear-off, and may provide an important reference geological record for this process. We find that the commonly applied conceptual geological signatures of slab break-off do not apply to the India-Asia collision zone, or to similar settings and histories such as the Arabia-Eurasia collision zone. Our study provides more realistic boundary conditions for future numerical models that aim to assess the dynamics of subduction termination and its geological signatures.</p>

Delineation of lithosphere structure and characterization of the Moho geometry under the Himalaya–Karakoram–Tibet collision zone using surface-wave tomography

2019 ◽  
Vol 481 (1) ◽  
pp. 19-40 ◽  
Author(s):  
Naresh Kumar ◽  
A. Aoudia ◽  
M. Guidarelli ◽  
Vivek G. Babu ◽  
Devajit Hazarika ◽  
...  
Keyword(s):  
Tarim Basin ◽  
Indian Plate ◽  
Moho Depth ◽  
S Wave ◽  
Low Velocity ◽  
Period Range ◽  
Velocity Models ◽  
Collision Zone ◽  
The Himalaya ◽  
Group Velocities

AbstractGroup velocities for a period range of 6–60 s for the fundamental mode of the Rayleigh wave passing across the Himalaya–Karakoram–Tibet orogen are used to delineate the structure of the upper lithosphere using the data from 35 broadband seismic stations. 2D tomography velocity maps of group velocities were obtained at grids of 1° separation. Redefined local dispersion curves are inverted non-linearly to obtain 1D velocity models and to construct a 3D image of the S-wave structure down to a depth of 90 km.The Moho discontinuity is correlated with c. 4.0 km s−1 S-wave velocity. The results depict a NE-dipping trend of the Moho depth from c. 40 km beneath the frontal part of the Himalaya to up to c. 70–80 km beneath the collision zone before shallowing substantially to c. 40 km beneath the Tarim Basin. The study also reveals thick deposits of sediments in the Indo-Gangetic plains and the Tarim Basin. A broad low-velocity zone at mid-crustal depth in the western Tibetan Plateau, the Karakoram region and the surface-collision part of the India–Eurasia tectonic plates is interpreted as the effect of partial melting and/or the presence of aqueous fluid. The high velocities in the southern deeper part indicate that the lower crust and uppermost mantle of the Indian Plate are dense and cold.

The Making of the Himalaya, Karakoram, and Tibetan Plateau

2013 ◽  
Author(s):  
Mike Searle
Keyword(s):  
Tibetan Plateau ◽  
Plate Boundary ◽  
Indian Plate ◽  
North West ◽  
Geological Interpretation ◽  
Mountain Ranges ◽  
The Road ◽  
The North ◽  
On The Road ◽  
The Himalaya

My quest to figure out how the great mountain ranges of Asia, the Himalaya, Karakoram, and Tibetan Plateau were formed has thus far lasted over thirty years from my first glimpse of those wonderful snowy mountains of the Kulu Himalaya in India, peering out of that swaying Indian bus on the road to Manali. It has taken me on a journey from the Hindu Kush and Pamir Ranges along the North-West Frontier of Pakistan with Afghanistan through the Karakoram and along the Himalaya across India, Nepal, Sikkim, and Bhutan and, of course, the great high plateau of Tibet. During the latter decade I have extended these studies eastwards throughout South East Asia and followed the Indian plate boundary all the way east to the Andaman Islands, Sumatra, and Java in Indonesia. There were, of course, numerous geologists who had ventured into the great ranges over the previous hundred years or more and whose findings are scattered throughout the archives of the Survey of India. These were largely descriptive and provided invaluable ground-truth for the surge in models that were proposed to explain the Himalaya and Tibet. When I first started working in the Himalaya there were very few field constraints and only a handful of pioneering geologists had actually made any geological maps. The notable few included Rashid Khan Tahirkheli in Kohistan, D. N. Wadia in parts of the Indian Himalaya, Ardito Desio in the Karakoram, Augusto Gansser in India and Bhutan, Pierre Bordet in Makalu, Michel Colchen, Patrick LeFort, and Arnaud Pêcher in central Nepal. Maps are the starting point for any geological interpretation and mapping should always remain the most important building block for geology. I was extremely lucky that about the time I started working in the Himalaya enormous advances in almost all aspects of geology were happening at a rapid pace. It was the perfect time to start a large project trying to work out all the various geological processes that were in play in forming the great mountain ranges of Asia. Satellite technology suddenly opened up a whole new picture of the Earth from the early Landsat images to the new Google Earth images.

Structure of the North Indian continental margin in the Ladakh–Zanskar Himalayas: implications for the timing of obduction of the Spontang ophiolite, India–Asia collision and deformation events in the Himalaya

1997 ◽  
Vol 134 (3) ◽  
pp. 297-316 ◽  
Author(s):  
MIKE SEARLE ◽  
RICHARD I. CORFIELD ◽  
BEN STEPHENSON ◽  
JOE MCCARRON
Keyword(s):  
Continental Margin ◽  
Suture Zone ◽  
Indian Plate ◽  
Normal Faults ◽  
Initial Contact ◽  
Crustal Shortening ◽  
Northern Margin ◽  
The North ◽  
Late Tertiary ◽  
The Himalaya

The collision of India and Asia can be defined as a process that started with the closing of the Tethyan ocean that, during Mesozoic and early Tertiary times, separated the two continental plates. Following initial contact of Indian and Asian continental crust, the Indian plate continued its northward drift into Asia, a process which continues to this day. In the Ladakh–Zanskar Himalaya the youngest marine sediments, both in the Indus suture zone and along the northern continental margin of India, are lowermost Eocene Nummulitic limestones dated at ∼54 Ma. Along the north Indian shelf margin, southwest-facing folded Palaeocene–Lower Eocene shallow-marine limestones unconformably overlie highly deformed Mesozoic shelf carbonates and allochthonous Upper Cretaceous shales, indicating an initial deformation event during the latest Cretaceous–early Palaeocene, corresponding with the timing of obduction of the Spontang ophiolite onto the Indian margin. It is suggested here that all the ophiolites from Oman, along western Pakistan (Bela, Muslim Bagh, Zhob and Waziristan) to the Spontang and Amlang-la ophiolites in the Himalaya were obducted during the late Cretaceous and earliest Palaeocene, prior to the closing of Tethys.The major phase of crustal shortening followed the India–Asia collision producing spectacular folds and thrusts across the Zanskar range. A new structural profile across the Indian continental margin along the Zanskar River gorge is presented here. Four main units are separated by major detachments including both normal faults (e.g. Zanskar, Karsha Detachments), southwest-directed thrusts reactivated as northeast-directed normal faults (e.g. Zangla Detachment), breakback thrusts (e.g. Photoksar Thrust) and late Tertiary backthrusts (e.g. Zanskar Backthrust). The normal faults place younger rocks onto older and separate two units, both showing compressional tectonics, but have no net crustal extension across them. Rather, they are related to rapid exhumation of the structurally lower, middle and deep crustal metamorphic rocks of the High Himalaya along the footwall of the Zanskar Detachment. The backthrusting affects the northern margin of the Zanskar shelf and the entire Indus suture zone, including the mid-Eocene–Miocene post-collisional fluvial and lacustrine molasse sediments (Indus Group), and therefore must be Pliocene–Pleistocene in age. Minimum amounts of crustal shortening across the Indian continental margin are 150–170 km although extreme ductile folding makes any balancing exercise questionable.

scholarly journals Geodynamics of the Indian Lithospheric Plate relative to the neighbouring Plates as revealed by Space Geodetic Measurements

2014 ◽  
Vol XL-8 ◽  
pp. 53-56 ◽  
Author(s):  
S. Krishna ◽  
J. Mathew ◽  
R. Majumdar ◽  
P. Roy ◽  
K. Vinod Kumar
Keyword(s):  
Relative Velocity ◽  
Average Velocity ◽  
Positional Information ◽  
Indian Plate ◽  
Eurasian Plate ◽  
Dynamic Nature ◽  
Large Magnitude ◽  
International Gnss Service ◽  
Collision Zone ◽  
Crustal Dynamics

The Indian Plate is highly dynamic in nature which in turn makes the Indo-Eurassian collision zone the foci of most of the historic large magnitude earthquakes. Processing of positional information from continuously observing reference stations is one of the space based geodetic techniques used globally and nationally to understand the crustal dynamics. The present study evaluates the dynamic nature of the Indian plate relative to its adjoining plates using the permanent GPS data (2011 to 2013) of 12 International GNSS Service (IGS), which are spread across the Indian, Eurassian, Australian, Somaliyan and African plates. The data processing was carried out using GAMIT/GLOBK software. The results indicate that the average velocity for the two IGS stations on the Indian Plate (Hyderabad and Bangalore) is 54.25 mm/year towards NE in the ITRF-2008 reference frame. The relative velocity of various stations with respect to the Indian plate has been estimated using the Bangalore station and has been found that the stations in the Eurasian plate (Lhasa, Urumqi, Bishkek and Kitab) are moving with velocity ranging from 25 to 33 mm/year in the SE direction resulting in compressional interaction with the Indian plate. This study reveals and confirms to the previous studies that the Indian- Eurassian-Australian Plates are moving at different relative velocities leading to compressional regimes at their margins leading to seismicity in these zones.

scholarly journals (U-Th)/He Thermochronology of the Indus Group, Ladakh, Northwest India: Is Neogene Cooling a Continental-Scale Thermal Event in the India-Asia Collision Zone?

Lithosphere ◽  
2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
G. Bhattacharya ◽  
D. M. Robinson ◽  
D. A. Orme
Keyword(s):  
Regional Scale ◽  
Detrital Zircons ◽  
Indus Basin ◽  
Indian Plate ◽  
Data Set ◽  
Continental Scale ◽  
Collision Zone ◽  
History Of ◽  
Ca 50 ◽  
Northwest India

Abstract The India-Asia continental collision zone archives a sedimentary record of the tectonic, geodynamic, and erosional processes that control the thermal history of the Himalayan orogenic interior since the onset of collision in early Paleogene time. In this paper, we present new (U-Th)/He thermochronometric cooling age data from 18 detrital zircons (ZHe) and 19 detrital apatites (AHe) of the early Eocene–early Miocene (ca. 50–23 Ma) continental facies of the Indus Group along the India-Asia collision zone in Ladakh, northwest (NW) India. This along-strike regional-scale low-temperature thermochronometric data set from the Indus basin is the first report of ZHe and AHe cooling ages from western and eastern Ladakh. Thermal modeling of our ZHe and AHe cooling ages indicates a postdepositional Neogene cooling signal in the Indus Group. Cooling initiated at ca. 21–19 Ma, was operational along the ~300 km strike of the collision zone in NW India by ca. 11 Ma, and continued until ca. 3 Ma. The Miocene cooling signal, also present along the India-Asia collision zone in south Tibet, is a continental-scale cooling event likely linked to increased erosional efficiency by the Indus and Yarlung Rivers across an elevated region resulting from the subduction dynamics of the underthrusting Indian plate.

Colliding Continents

2013 ◽  
Author(s):  
Mike Searle
Keyword(s):  
Indian Plate ◽  
Mountain Range ◽  
Polar Regions ◽  
Geological Evidence ◽  
North West ◽  
Ice Cap ◽  
The North ◽  
West Himalaya ◽  
Tectonically Active ◽  
The Himalaya

The Himalaya is the greatest mountain range on Earth: the highest, longest, youngest, the most tectonically active, and the most spectacular of all. Unimaginable geological forces created these spectacular peaks. Indeed, the crash of the Indian plate into Asia is the biggest known collision in geological history, giving birth to the Himalaya and Karakoram, one of the most remote and savage places on Earth. In this beautifully illustrated book, featuring spectacular color photographs throughout, one of the most experienced field geologists of our time presents a rich account of the geological forces that were involved in creating these monumental ranges. Over three decades, Mike Searle has transformed our understanding of this vast region. To gather his vital geological evidence, he has had to deploy his superb skills as a mountaineer, spending weeks at time in remote and dangerous locations. Searle weaves his own first-hand tales of discovery with an engaging explanation of the processes that formed these impressive peaks. His narrative roughly follows his career, from his early studies in the north west Himalaya of Ladakh, Zanskar and Kashmir, through several expeditions to the Karakoram ranges (including climbs on K2, Masherbrum, and the Trango Towers, and the crossing of Snow Lake, the world's largest ice cap outside polar regions), to his later explorations around Everest, Makalu, Sikkim and in Tibet and South East Asia. The book offers a fascinating first-hand account of a major geologist at work-the arduous labor, the eureka moments, and the days of sheer beauty, such as his trek to Kathmandu, over seven days through magnificent rhododendron forests ablaze in pinks, reds and white and through patches of bamboo jungle with hanging mosses. Filled with satellite images, aerial views, and the author's own photographs of expeditions, Colliding Continents offers a vivid account of the origins and present state of the greatest mountain range on Earth.

Towards resolving the metamorphic enigma of the Indian Plate in the NW Himalaya of Pakistan

2019 ◽  
Vol 483 (1) ◽  
pp. 255-279 ◽  
Author(s):  
Peter J. Treloar ◽  
Richard M. Palin ◽  
Michael P. Searle
Keyword(s):  
Leading Edge ◽  
Shear Zones ◽  
Indian Plate ◽  
Main Central Thrust ◽  
Nw Himalaya ◽  
Basement Rocks ◽  
Upper Paleozoic ◽  
The Himalaya ◽  
Temperature Path ◽  
Tethyan Himalaya

AbstractThe Pakistan part of the Himalaya has major differences in tectonic evolution compared with the main Himalayan range to the east of the Nanga Parbat syntaxis. There is no equivalent of the Tethyan Himalaya sedimentary sequence south of the Indus–Tsangpo suture zone, no equivalent of the Main Central Thrust, and no Miocene metamorphism and leucogranite emplacement. The Kohistan Arc was thrust southward onto the leading edge of continental India. All rocks exposed to the south of the arc in the footwall of the Main Mantle Thrust preserve metamorphic histories. However, these do not all record Cenozoic metamorphism. Basement rocks record Paleo-Proterozoic metamorphism with no Cenozoic heating; Neo-Proterozoic through Cambrian sediments record Ordovician ages for peak kyanite and sillimanite grade metamorphism, although Ar–Ar data indicate a Cenozoic thermal imprint which did not reset the peak metamorphic assemblages. The only rocks that clearly record Cenozoic metamorphism are Upper Paleozoic through Mesozoic cover sediments. Thermobarometric data suggest burial of these rocks along a clockwise pressure–temperature path to pressure–temperature conditions of c. 10–11 kbar and c. 700°C. Resolving this enigma is challenging but implies downward heating into the Indian plate, coupled with later development of unconformity parallel shear zones that detach Upper Paleozoic–Cenozoic cover rocks from Neoproterozoic to Paleozoic basement rocks and also detach those rocks from the Paleoproterozoic basement.

What is driving India-Asia convergence?

2021 ◽  
Author(s):  
Santanu Bose ◽  
Wouter P Schellart ◽  
Vincent Strak ◽  
João C. Duarte ◽  
Zhihao Chen
Keyword(s):  
Subduction Zones ◽  
Boundary Migration ◽  
Physical Models ◽  
Plate Motion ◽  
Indian Plate ◽  
Mountain Range ◽  
Complete Disappearance ◽  
The Tibetan Plateau ◽  
Main Driver ◽  
The Himalaya

<p>The Himalaya and the Tibetan plateau, the highest mountain range on Earth, have been growing continuously for the last 55 Myrs since India collided with Eurasia. The forces driving this protracted mountain building process are still not fully understood, and continue to puzzle Earth Scientists. Although it is now well accepted that subduction zones are the main driver for plate motion, plate boundary migration, and mantle flow in the asthenosphere, their role in driving Indian indentation into the Asian landmass has never been tested with geodynamic models. This study uses four-dimensional geodynamic physical models to test the role of lateral subduction zones in driving the India-Asia collision. The objective of our study is to investigate if the slab pull force of the Sunda and Makran slabs have any role to play in the dynamics of the ongoing India-Asia convergence, particularly after the complete disappearance of the Tethyan slab, which was primarily steering the northward travel of the Indian plate since late Jurassic. To address this issue, we performed three experiments by varying the size and configuration of the subducting plate in the initial model setup.  Our experimental results show that active subduction of the Indo-Australian plate along the Sunda subduction zone is the main driver of the India-Asia convergence, Indian indentation, the growth of the Himalaya-Tibet mountains, and the eastward extrusion of southeast Asia. Our work further suggests that the protracted growth of collisional mountains on Earth requires nearby active subduction zones and, therefore, Himalayan-type orogens may have been rare in the Earth’s history.</p>

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