A review of definitions of the Himalayan Main Central Thrust

Martin, Aaron J.

doi:10.1007/s00531-016-1419-8

Cited by 77 publications

(49 citation statements)

References 117 publications

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“…The Main Central Thrust (MCT; Figure ) plays a central role in many models for the evolution of the Himalayas (e.g., Bollinger et al, ; Carosi et al, ; England et al, ; Harrison et al, ; Henry et al, ; Le Fort, ; Martin, ; Parsons et al, ; Searle & Rex, , among others). The MCT places the high‐grade (>600 °C) Greater Himalayan Crystallines (GHCs) over lower grade Lesser Himalayan Formations (LHFs) along a broad scale 8–12‐km thick shear zone (see review in Mukhopadhyay et al, ).…”

Section: Geological Background: Himalayan Case Studymentioning

confidence: 99%

Modeling High‐Resolution Pressure‐Temperature Paths Across the Himalayan Main Central Thrust (Central Nepal): Implications for the Dynamics of Collision

et al. 2018

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High-resolution, garnet-based pressure-temperature (P-T) paths were obtained for nine rocks across the Himalayan Main Central Thrust (MCT) (Marsyangdi River transect, central Nepal). Paths were created using garnet and whole rock compositions as input parameters into a semiautomated Gibbs free-energy-minimization technique. The conditions recorded by the paths, in general, yield similar T but lower P compared to estimates from mineral equilibria and quartz-in-garnet Raman barometry. The paths are used to modify a model based on a two-dimensional finite difference solution to the diffusion-advection equation. In this model, P-T paths recorded by the footwall garnets result from fault motion at specified times, thermal advection, and alteration of topography. The best fit between the high-resolution P-T paths and model predictions is that from 25 to 18 Ma, samples within the MCT footwall moved at 5 km/Ma, while those in the hanging wall moved at 10 km/Ma. Under these conditions, topography grew to 3.5 km. A pause in activity along the MCT between 18 and 15 Ma allows heat to advect and may be due to a transfer of tectonic activity to the structures closer to the Indian subcontinent. During this time, the topography erodes at a rate of 1.5 km/Ma. Thrusting within the MCT footwall reactivates between 8 and 2 Ma with exhumation rates up to 12 mm/yr since the Pliocene. The results suggest the potential for the highestresolution garnet-based P-T paths to record both the thermobarometric consequences of fault motion and large-scale erosion.Plain Language Summary The Main Central Thrust (MCT) is a major Himalayan fault system largely responsible for the generation of its high topography. Garnets across the MCT record their growth history in the crust through changes in their chemistry. These chemical changes can be extracted and modeled. Here we report detailed pressure-temperature paths recorded by garnets collected across the MCT along the Marsyangdi River in central Nepal. The paths track evolving conditions in the Earth's crust when the MCT was active during the growth of the Himalayas. The results suggest that the MCT formed as individual rock packages moved at distinct times. Further modeling makes predictions about how the Himalayas developed, including that the MCT may have ceased motion 18-15 million years ago, as other faults closer to the Indian subcontinent became active, and that it reactivated 8-2 million years ago, leading to the generation of high topography. The modeling also suggests that very high erosion rates occurred within the range after reactivation. Although garnets have long been used to understand how fault systems evolve, we provide details of an approach that allows higher-resolution data to be extracted from them and show how they could be used to track large-scale erosion.

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Section: Geological Background: Himalayan Case Studymentioning

confidence: 99%

Modeling High‐Resolution Pressure‐Temperature Paths Across the Himalayan Main Central Thrust (Central Nepal): Implications for the Dynamics of Collision

et al. 2018

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“…Together, these new approaches have catapulted our knowledge of Himalayan thrust belt shortening and kinematic history, with implications for crustal thickening throughout the Himalayan‐Tibetan orogenic system. As in all scientific endeavors, however, the new data raise new questions, and notable debates have emerged concerning along‐strike correlation of Himalayan stratigraphic units and tectonostratigraphic terranes [ DeCelles et al ., ; Myrow et al ., ; Richards et al ., ; Yin , ; McQuarrie et al ., ], the geometry and kinematics of the Main Central Thrust [ Yin , ; Webb et al ., , ; Searle et al ., ; Webb , ; Célérier et al ., ; He et al ., ; Larson et al ., ], the best way(s) to identify and map major Himalayan thrust faults (especially the Main Central Thrust [ Martin et al ., ; Richards et al ., ; Searle et al ., ; Webb et al ., ; Mottram et al ., ; Martin , ]), and the underlying geodynamic mechanisms driving deformation [ Burg et al ., ; Nelson et al ., ; Grujic et al ., ; Avouac , ; Beaumont et al ., , ; Jamieson et al ., ; Robinson and Pearson , ; Yin , ; Kellett et al ., ; He et al ., ].…”

Section: Introductionmentioning

confidence: 99%

“…EASTERN HIMALAYAN THRUST BELT 2995 PUBLICATIONS Tectonics RESEARCH ARTICLE all scientific endeavors, however, the new data raise new questions, and notable debates have emerged concerning along-strike correlation of Himalayan stratigraphic units and tectonostratigraphic terranes [DeCelles et al, 2000;Myrow et al, 2003;Richards et al, 2005;Yin, 2006;McQuarrie et al, 2013], the geometry and kinematics of the Main Central Thrust [Yin, 2006;Webb et al, 2007Webb et al, , 2011Searle et al, 2008;Webb, 2013;Célérier et al, 2009;He et al, 2015;Larson et al, 2015], the best way(s) to identify and map major Himalayan thrust faults (especially the Main Central Thrust [Martin et al, 2005;Richards et al, 2005;Searle et al, 2008;Webb et al, 2013;Mottram et al, 2014;Martin, 2016]), and the underlying geodynamic mechanisms driving deformation [Burg et al, 1984;Nelson et al, 1996;Grujic et al, 2002;Avouac, 2003;Beaumont et al, 2001Beaumont et al, , 2004Jamieson et al, 2004;Robinson and Pearson, 2006;Yin, 2006;Kellett et al, 2013;He et al, 2015].…”

Section: Introductionmentioning

confidence: 99%

Along-strike continuity of structure, stratigraphy, and kinematic history in the Himalayan thrust belt: The view from Northeastern India

et al. 2016

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The Himalaya consists of thrust sheets tectonically shingled together since ~58 Ma as India collided with and slid beneath Asia. Major Himalayan structures, including the South Tibetan Detachment (STD), Main Central Thrust (MCT), Lesser Himalayan Duplex (LHD), Main Boundary Thrust (MBT), and Main Frontal Thrust (MFT), persist along strike from northwestern India to Arunachal Pradesh near the eastern end of the orogenic belt. Previous work suggests significant basement involvement and a kinematic history unique to the Arunachal Himalaya. We present new geologic and geochronologic data to support a regional structural cross section and kinematic restoration of the Arunachal Himalaya. Large Paleoproterozoic orthogneiss bodies (Bomdila Gneiss) previously interpreted as Indian basement have ages of ~1774–1810 Ma, approximately 50 Ma younger than Lesser Himalayan strata into which their granitic protoliths intruded. Bomdila Gneiss is therefore part of the Lesser Himalayan cover sequence, and no evidence exists for basement involvement in the Arunachal Himalaya. Minimum shortening in rocks structurally beneath the STD is ~421 km. The MCT was active during the early Miocene; STD extension overlapped MCT shortening and continued until approximately 15–12 Ma; and growth of the LHD began ~11 Ma, followed by slip along the MBT (post‐7.5 Ma) and MFT (post‐1 Ma) systems. Earlier thrusting events involved long‐distance transport of strong, low‐taper thrust sheets, whereas events after 12–10 Ma stacked smaller, weaker thrust sheets into a steeply tapered orogenic wedge dominated by duplexing. A coeval kinematic transition is observed in other Himalayan regions, suggesting that orogenic wedge behavior was controlled by rock strength and erodibility.

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“…During the Himalayan orogeny, the GHS was metamorphosed at greenschist to granulite facies conditions and was extensively deformed from the Eocene to the Miocene (Carosi et al., ; Godin et al., ; Grujic, Hollister, & Parrish, ; Grujic, Warren, & Wooden, ; Iaccarino, Montomoli, Carosi, Massone, et al., ; Iaccarino et al., ; Inger & Harris, ; Larson & Cottle, ; Larson et al., ; Pêcher, ; Soucy La Roche, Godin, Cottle, et al., ; Streule, Searle, Waters, & Horstwood, ; Vannay & Hodges, ). The base of the GHS is marked by the Main Central thrust (MCT) zone, a several km‐thick top‐to‐the‐SW shear zone that propagated down‐section from the early Oligocene to the late Miocene as slices of footwall rocks were successively accreted to the hangingwall (Gansser, ; Hunter, Weinberg, Wilson, Luzin, & Misra, ; Larson, Ambrose, Webb, Cottle, & Shrestha, ; Martin, 2017b; Mottram et al., ; Searle et al., ).…”

Section: Geology Of the Central Himalayamentioning

confidence: 99%

“…Because several definitions have been used to identify the MCT (reviews in Martin, 2017b; Searle et al., ), metamorphic units have been variably assigned to the GHS or the LHS depending on the interpreted position of the MCT within the volume of pervasively sheared rocks, the MCT zone. For simplicity, and to put emphasis on the tectonometamorphic evolution of the metamorphic rocks rather than on GHS or LHS classification, we use the term Himalayan metamorphic core (HMC) to refer to all rocks that record evidence of mid‐crustal deformation and metamorphism during the Himalayan orogeny (e.g., Cottle, Larson, & Kellett, ).…”

Section: Geology Of the Central Himalayamentioning

confidence: 99%

Tectonometamorphic evolution of the tip of the Himalayan metamorphic core in the Jajarkot klippe, west Nepal

Godin

Cottle

Kellett

2018

Journal Metamorphic Geology

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New phase equilibrium modelling, combined with U–Th/Pb petrochronology on monazite and xenotime, and 40Ar/39Ar geochronology on white mica, reveal the style of deformation and metamorphism near the southern tip of the extruded Himalayan metamorphic core (HMC). In the Jajarkot klippe, west Nepal foreland, greenschist to lower amphibolite facies metamorphism is entirely constrained to the Cenozoic Himalayan orogeny, in contrast with findings from other foreland klippen in the central Himalaya. HMC rocks exposed in the Jajarkot klippe yield short‐lived, hairpin pressure–temperature–time–deformation paths that peaked at 550–600°C and 750–1,200 MPa at 25 Ma. The Main Central thrust (MCT) and the South Tibetan detachment (STD) bound the base and the top of the HMC, respectively, and were active simultaneously for at least part of their deformation history. The STD was active at c. 27–26 Ma and possibly as late as c. 19 Ma, while the MCT may have been active as early as 27 Ma and was still active at c. 22 Ma. The tectonometamorphic conditions in the Jajarkot klippe are characteristic of crustal thickening and footwall accretion of new material at the tip of the extruding metamorphic orogenic core. Our new results reveal that collisional processes active in the middle to late Miocene at the base of the HMC now exposed in the hinterland were also active earlier, during the Oligocene, at the tip of the southward‐extruding middle crust.

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A review of definitions of the Himalayan Main Central Thrust

Cited by 77 publications

References 117 publications

Modeling High‐Resolution Pressure‐Temperature Paths Across the Himalayan Main Central Thrust (Central Nepal): Implications for the Dynamics of Collision

Modeling High‐Resolution Pressure‐Temperature Paths Across the Himalayan Main Central Thrust (Central Nepal): Implications for the Dynamics of Collision

Along-strike continuity of structure, stratigraphy, and kinematic history in the Himalayan thrust belt: The view from Northeastern India

Tectonometamorphic evolution of the tip of the Himalayan metamorphic core in the Jajarkot klippe, west Nepal

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