The South Tibet detachment shear zone in the Dinggye areaTime constraints on extrusion models of the Himalayas

Leloup, Philippe‐Hervé; Mahéo, Gweltaz; Arnaud, Nicolas; Kali, E.; Boutonnet, E.; Liu, Dunyi; Liu, Xiaohan; Li, Haibing

doi:10.1016/j.epsl.2009.12.035

Cited by 116 publications

(119 citation statements)

References 108 publications

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“…North of the MFT, the décollement of the Indian basement is thought to extend with flat geometry beneath the Lesser Himalaya and to form a steeper ramp at the front of the High Himalaya (Lavé and Avouac 2000). The MBT is a series of thrusts that separate the Lesser Himalaya sediments from the Tertiary Siwalik sedimentary belt (e.g., Leloup et al 2010;Ni and Barazangi 1984). The MCT is a series of thrusts separating the High Himalaya from the Lesser Himalaya (ibid.).…”

Section: Tectonics and Setting Of Receiver Faultsmentioning

confidence: 99%

Investigation of Coulomb stress changes in south Tibet (central Himalayas) due to the 25th April 2015 M W 7.8 Nepal earthquake using a Coulomb stress transfer model

Cheng

Meng

2016

Earthq Sci

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After M W 7.8 Nepal earthquake occurred, the rearrangement of stresses in the crust commonly leads to subsequent damaging earthquakes. We present the calculations of the coseismic stress changes that resulted from the 25th April event using models of regional faults designed according to south Tibet-Nepal structure, and show that some indicative significant stress increases. We calculate static stress changes caused by the displacement of a fault on which dislocations happen and an earthquake occurs. A M W 7.3 earthquake broke on 12 May at a distance of * 130 km SEE of the M W 7.8 earthquake, whose focus roughly located on high Coulomb stress change (CSC) site. Aftershocks (first 15 days after the mainshock) are associated with stress increase zone caused by the main rupture. We set receiver faults with specified strikes, dips, and rakes, on which the stresses imparted by the source fault are resolved. Four group normal faults to the north of the Nepal earthquake seismogenic fault were set as receiver faults and variant results followed. We provide a discussion on Coulomb stress transfer for the seismogenic fault, which is useful to identify potential future rupture zones.

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Section: Tectonics and Setting Of Receiver Faultsmentioning

confidence: 99%

Investigation of Coulomb stress changes in south Tibet (central Himalayas) due to the 25th April 2015 M W 7.8 Nepal earthquake using a Coulomb stress transfer model

Cheng

Meng

2016

Earthq Sci

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“…This confirms the view that NSTR is probably the result of N-S contraction [29] and provides unequivocal evidence for the transformation of tectonic regime. In order to accurately constrain the time of the transformation of tectonic regime from N-S extension to N-S contraction, we summarize and analyze the ages of STDS and NSTRs in Gyirong and other areas in Himalayan orogen ( Figure 7) [4][5][6][7][8][9][10][12][13][14][15][16][17]22,28,[30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48]. The result shows that the STDS was active from ca.…”

Section: Middle-miocene Transformation Of Tectonic Regime In Himalayamentioning

confidence: 99%

“…At this time, the regime of N-S extension was dominant. When the India-Asia convergence speeded up, the Himalaya experienced a rapid deformation, resulting in Figure 8 Statistical diagram of the U-Pb/U-(Th)-Pb ages of leucogranites and 40 Ar/ 39 Ar ages of leucogranites and metasedimentary rocks in Himalayan orogen (data from [1,[4][5][6][7][8][9][10][11][12][13][15][16][17][18][22][23][24]30,). the thrusting and shorting.…”

Section: Geodynamic Implications On the Transformation Of Tectonic Rementioning

confidence: 99%

“…(2) After early Oligocene, the tectonic regime transformed from N-S contraction to N-S extension. Between late Oligocene and early Miocene (28.4-16.2 Ma), the northern Himalayas experienced widespread extension, resulting in large scale extensional tectonics, such as the north-dipping STDS [4][5][6][7][8][9][10][11][12][13][14][15][16]. (3) In middleMiocene (~13 Ma), the tectonic regime shifted to E-W extension [17,18], which formed the NSTR cutting the STDS, such as Yadong-Gulu rift, Nima-Dingri rift and XainzaDinggye rift.…”

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confidence: 99%

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Middle-Miocene transformation of tectonic regime in the Himalayan orogen

et al. 2012

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Understanding the multiple tectonic transformations during the Himalayan orogeny is significant in evaluating the evolution of Himalayan orogen. In the Gyirong area in south Tibet, deformed leucogranitic veins in the biotite-plagioclase gneisses of Greater Himalayan crystalline complex (GHC) constitute south-vergent asymmetric folds. The reconstruction of the veins shows that they experienced two generations of deformation under different tectonic regimes: an earlier top-to-north extension and a later top-to-south thrusting, implying a tectonic transformation from N-S extension to N-S shortening. Zircons LA-ICP-MS U-Pb dating of the leucogranite shows that it was emplaced during 21.03-18.7 Ma. The data suggest that the tectonic transformation occurred after 18.7 Ma. The chronological data of South Tibet detachment system (STDS) and North-South trending rift (NSTR) from Gyirong and other areas indicate that the Himalayan orogeny was in a period of tectonic transformation from N-S extension to N-S shortening during 19-13 Ma. The transformation of tectonic regime was probably controlled by the India-Asia convergence rate. An increase in the convergence rate resulted in N-S shortening of the orogen, thrusting and folding, with coeval formation of the NSTR in Tibet. A decrease in the convergence rate led to N-S extension and reactivation of the STDS.

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“…Some studies have suggested deformation linked with the STDS could have migrated upwards prior to localize in the top to the north South Tibet Detachment (STD) shear zone [14,25]. Because this hypothesis has major bearings not only on the history of the STD shear zone but also on the mechanics of the Himalayan range building and on the mechanics of low angle detachment in general, it deserves to be investigated in more details.…”

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confidence: 99%

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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The South Tibet detachment shear zone in the Dinggye areaTime constraints on extrusion models of the Himalayas

Cited by 116 publications

References 108 publications

Investigation of Coulomb stress changes in south Tibet (central Himalayas) due to the 25th April 2015 M W 7.8 Nepal earthquake using a Coulomb stress transfer model

Investigation of Coulomb stress changes in south Tibet (central Himalayas) due to the 25th April 2015 M W 7.8 Nepal earthquake using a Coulomb stress transfer model

Middle-Miocene transformation of tectonic regime in the Himalayan orogen

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

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