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[Display omitted] • Crustal anisotropy results suggest simple shear deformation may be the main mode of crustal deformation in the central Tibetan Plateau. • A weak crustal anisotropic belt is observed beneath the Bangong-Nujiang Suture (BNS). • The weak deformation beneath the BNS and strong deformation on both sides lead to the formation of conjugate strike-slip faults. The dynamic processes responsible for the formation of the conjugate strike-slip faults in the central Tibet remain poorly understood. The crustal anisotropy can provide important constraints on the crustal deformation history and current state. Using data from a recently deployed seismic array (SANDWICH), we obtained crustal anisotropy results that reveal the deformation of the crust in the central Tibet with high resolution. The results show that most stations exhibit strong crustal anisotropy and nearly E-W fast orientations. Our results, when combined with previously revealed upper crustal anisotropy, indicates that the deformation in the upper and mid-lower crust is decoupled. The most prominent feature in our results is a weak crustal anisotropy belt along the BNS, suggesting the mid-lower crust has not undergone strong deformation. We propose that the combination of stable BNS and strong deformation on both sides of BNS in the mid-lower crust caused the formation of conjugate strike-slip faults. [ABSTRACT FROM AUTHOR]

An east–west trending, high-density seismic array was deployed along the eastern margin of the Tibetan Plateau to investigate its eastward expansion. The 160 km long array spans the Ruoergai basin, Minjiang fault, Minshan Mountains, Tazang fault, and West Qinling. The array included 330 short-period seismographs spaced at 500 m intervals, which recorded teleseismic 3-component waveforms over a one month period. P-wave receiver functions calculated from 35 teleseismic events provided an image of crustal structure. The results show a massive thrust nappe structure around the Minshan Mountains and beneath the Minjiang fault. We suggest that this nappe formed after the closure of the Paleo-Tethyan ocean. The resultant Triassic thrusting contributed to partial uplift of the eastern Ruoergai basin and the Minshan Mountains in middle-to-late Miocene time. Receiver function images show that the Tazang fault is a crustal-scale rupture cutting across the Moho. The western Tazang fault appears as a nearly vertical strike-slip fault accommodating left lateral shear at the terminus of the eastern Kunlun fault. After clockwise rotation from an approximate east–west orientation to a nearly north–south orientation, the eastern Tazang fault became a west-dipping thrust fault, which caused crustal thickening beneath the Minshan Mountains and the West Qinling. Our results suggest that late Cenozoic uplift of the eastern margin of the plateau is produced by eastward overthrusting and crustal shortening, processes that absorbed slip along the Tazang and Kunlun faults. [ABSTRACT FROM AUTHOR]

• The Pn velocity model is established in the Tibetan plateau using the interstation travel-time difference method. • Wide low V Pn (7.8 km/s) indicates a thin lithospheric mantle and a possible channel of asthenospheric flow. • The lithospheric mantle of the Tibetan plateau does not escape southeastward. A mass of lithospheric shortening occurred beneath the Tibetan Plateau due to the collision between the Indian and Eurasian plates. The extrusion of the upper crust beneath the Tibetan Plateau has been widely accepted, but whether the lithospheric mantle escapes laterally by creep deformation or rigid-block extrusion remains unclear. Based on the Pn travel time data, the velocity structure of the uppermost mantle in eastern and southeastern Tibetan Plateau was obtained by using the interstation travel-time difference method. The results show an obviously high Pn velocity beneath the Sichuan Basin and Qaidam Basin, indicating that the areas are stable blocks. The high Pn velocity beneath the eastern Lhasa terrane may be related to the underplating of the Indian lithospheric plate to the north. The Qilian block located in the north of the Kunlun fault appears as a normal Pn velocity, which indicates a mean lithospheric mantle thickness. A significantly low Pn velocity with an average of ~7.8 km/s in eastern and southeastern Tibetan Plateau, including the eastern Songpan–Ganzi terrane, the Chuan–Dian Diamond Block, and the northern part of Yunnan Province, indicates that the lithospheric mantle is relatively thin in these regions. Combined with other geologic and geophysical results, we propose that the lithospheric mantle of the plateau did not escape to eastern and southeastern Tibetan Plateau where the crust has been thickened by adding crustal material from the interior of the plateau. [ABSTRACT FROM AUTHOR]