Strain, deformation temperatures and vorticity of flow at the top of the Greater Himalayan Slab, Everest Massif, Tibet

Law, Richard D.; Searle, Mike; Simpson, Robert L.

doi:10.1144/0016-764903-047

Cited by 366 publications

(338 citation statements)

References 75 publications

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“…This has been demonstrated in detail by research over the last two decades in the High Himalaya by, for instance, Burchfiel et al (1992), Grujic et al (1996) and Law et al (2004). They all showed that the top of the High Himalayan zone is bounded by a normal fault, the South Tibetan Detachment, and the base of the zone by the Main Central Thrust (Fig.…”

Section: Normal Faults In Shortening and Extensional Environmentsmentioning

confidence: 74%

No need for lithospheric extension for exhuming (U)HP rocks by normal faulting

Ring

Glodny

2010

JGS

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Extensional deformation is commonly considered most important for exhuming rocks from great depths. However, the necessary space for extending the lithosphere is usually lacking. We show that significant exhumation of (U)HP rocks occurs in extrusion wedges, which have a normal fault at their top and a thrust fault at their base. The normal fault at the top of an extrusion wedge is a geometric effect and does not result from lithospheric extension. Therefore, the exhumation of (U)HP rocks in extrusion wedges allows substantial exhumation beneath a normal fault during horizontal shortening and does not cause lithospheric attenuation.

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Section: Normal Faults In Shortening and Extensional Environmentsmentioning

confidence: 74%

No need for lithospheric extension for exhuming (U)HP rocks by normal faulting

Ring

Glodny

2010

JGS

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“…7) developed for the Greater Himalaya along the southern margin of the Tibetan Plateau was proposed initially from field geological mapping and strain data combined with P-T constraints and U-Pb dating of metamorphic rocks and leucogranites (Searle & Rex 1989;Grujic et al 2002;Searle et al 2003Searle et al , 2006Law et al 2004Law et al , 2006Searle & Szulc 2005;Godin et al 2006). The channel flow model infers that a partially molten middle crust layer was extruded south from beneath southern Tibet to the Greater Himalaya during the Early Miocene, at c. 23-15 Ma.…”

Section: Himalayan Channel Flow Modelsmentioning

confidence: 99%

“…Clark & Royden 2000;Haines et al 2003) and (b) the Himalayan mid-crustal 'channel flow' model (e.g. Beaumont et al 2001Beaumont et al , 2004Grujic et al 2002;Searle et al 2003Searle et al , 2006Searle et al , 2010bLaw et al 2004Godin et al 2006).…”

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confidence: 99%

Crustal–lithospheric structure and continental extrusion of Tibet

Searle

Elliott

Phillips

et al. 2011

JGS

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231

154

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Crustal shortening and thickening to c. 70-85 km in the Tibetan Plateau occurred both before and mainly after the c. 50 Ma India-Asia collision. Potassic-ultrapotassic shoshonitic and adakitic lavas erupted across the Qiangtang (c. 50-29 Ma) and Lhasa blocks (c. 30-10 Ma) indicate a hot mantle, thick crust and eclogitic root during that period. The progressive northward underthrusting of cold, Indian mantle lithosphere since collision shut off the source in the Lhasa block at c. 10 Ma. Late Miocene-Pleistocene shoshonitic volcanic rocks in northern Tibet require hot mantle. We review the major tectonic processes proposed for Tibet including 'rigid-block', continuum and crustal flow as well as the geological history of the major strikeslip faults. We examine controversies concerning the cumulative geological offsets and the discrepancies between geological, Quaternary and geodetic slip rates. Low present-day slip rates measured from global positioning system and InSAR along the Karakoram and Altyn Tagh Faults in addition to slow long-term geological rates can only account for limited eastward extrusion of Tibet since Mid-Miocene time. We conclude that despite being prominent geomorphological features sometimes with wide mylonite zones, the faults cut earlier formed metamorphic and igneous rocks and show limited offsets. Concentrated strain at the surface is dissipated deeper into wide ductile shear zones.

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“…At these locations deformation linked with the STD stopped at ~12 Ma [14]. In the UHCS rocks below the STDsz deformation seems to be closer to pure shear than to simple shear, which is also found in the other portion of the STD [35,70] and probably started prior to 22.0±0.3 Ma and 27.4±0.2, 1500 and 3500 m below the STD respectively. In Gyirong deformation in the STDsz was active at ~26 Ma if the leucogranite is effectively syntectonic.…”

Section: Timing Of Ductile Deformation Beneath the Ndmentioning

confidence: 63%

Ductile deformation within Upper Himalaya Crystalline Sequence and geological implications, in Nyalam area, Southern Tibet

Liu

Leloup

et al. 2012

Chin. Sci. Bull.

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The South Tibet Detachment System (STDS) is a flat normal fault that separates the Upper Himalaya Crystalline Sequence (UHCS) below from the Tethyan Sedimentary Sequence (TSS) above. Timing of deformations related to the STDS is critical to understand the mechanism and evolution of the Himalaya collision zone. The Nyalam detachment (ND) (~86°E) locates in the middle portion of STDS (81°-89°E). Dating of deformed leucocratic dykes that are most probably syntectonic at different depth beneath the ND, allow us to constrain the timing of deformation. (1) Dyke T11N37 located ~3500 m structurally below the ND emplaced at 27.4± 0.2 Ma; (2) Dyke T11N32 located ~1400 m structurally below the ND emplaced at 22.0±0.3 Ma; (3) T11N25 located within the top to the north STD shear zone, ~150 m structurally below the ND, emplaced at 17.1±0.2 Ma. Combining ND footwall cooling history and T11N25 deformation temperature, we indicate a probable onset of top to the north deformation at ~16 Ma at this location. These results show an upward younging of the probable timing of onset of the deformation at different structural distance below the ND. We then propose a new model for deformation migration below the ND with deformation starting by pure shear deformation at depth prior to ~27.5 Ma that migrates upward at a rate of ~ 0.3 mm/a until ~18 Ma when deformation switches to top to the north shearing in the South Tibet Detachment shear zone (STDsz). As deformation on the ND stops at 14-13 Ma this would imply that significant top to the North motion would be limited to less than 5 Ma and would jeopardize the importance of lower channel flow.

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Strain, deformation temperatures and vorticity of flow at the top of the Greater Himalayan Slab, Everest Massif, Tibet

Cited by 366 publications

References 75 publications

No need for lithospheric extension for exhuming (U)HP rocks by normal faulting

No need for lithospheric extension for exhuming (U)HP rocks by normal faulting

Crustal–lithospheric structure and continental extrusion of Tibet

Ductile deformation within Upper Himalaya Crystalline Sequence and geological implications, in Nyalam area, Southern Tibet

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