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Defining the northern margin of the Tibetan Plateau, the Altyn Tagh Fault system (ATFs)exerts a crucial role in accommodating intracontinental deformation during the India-Asiaconvergence. The North Altyn fault (NAF), demarcating the western boundary of the ATFs inthe Altun Shan region, was testified to exist a structural shift from sinistral along-strikeslipping to thrusting during the Cenozoic era. However, the exact timing of the shift remainsan issue to be refined. In this study, we conducted LA-ICP-MS based apatite fission trackdating at massifs of both the hanging wall and footwall along the NAF, to shed light on datingthe thrusting-related exhumation of the NAF. The results show that the hanging wall massifsof the NAF present a quasi-isothermal quiescence during the early Cenozoic, followedby a rapid cooling phase with mean cooling rate of 6.66 ± 0.72 ˚ C / Ma since∼15 Ma, resulting from accelerated exhumation which has been interpreted tomark intense vertical uplift of the NAF. Significantly younger age (∼5 Ma) buthigher rate (15.33 ± 2.10 ˚ C / Ma) of rapid-cooling event occurred at the footwallcompared to the hanging wall suggests a northward propagation of thrusting into theinterior Tarim basin. Combining previous studies, we attribute the structural shift ofthe NAF from along-strike slipping to thrusting to the Mid-Miocene kinematicreorganization of the ATFs, supporting to the two-stage evolution model of theAFTs that: (1) during ∼50-15 Ma, the NAF acted as a part of the Altyn Tagh faultexperiencing along-strike slipping, with the Altun Shan elevated north within bigrestraining-double-bends; and (2) after ∼15 Ma, the Altyn Tagh fault cut through thedouble-bends with significant thrusting along the NAF, circumscribing the presenttriangle-shaped Altun Shan featured with uplifting south beginning at ∼15 Ma. [ABSTRACT FROM AUTHOR]

The Western Kunlun ranges and its foreland basin, the Tarim Basin, define the northwestmargin of the Tibetan Plateau, and provide important information on the Cenozoic expansionof the plateau after the India-Asia collision. In this study, we present a high-resolutionseismic reflection profile along the Hotan-Mazatagh transect of the Western Kunlun thrustsbelt in order to decipher the distribution of deformation and its propagation. Deformation inthis transect can be separated into three roughly east-west striking structures fromthe south to the north: the Hotan anticline, the Manan anticline, and the Mazataghthrust belt. The Hotan anticline is a fault-bend fold, mainly formed by the hangingwall sliding from the lower decóllement along the lower Cambrian units over apre-existing fault ramp into the upper decóllement that is located at the base ofthe Cenozoic strata. The Manan anticline, located ∼100 km north to the Hotananticline, is a reactivated low-amplitude fold with decreasing deformation upwards, theformation of which is mainly controlled by the lower decóllement. The Mazatagh thrustbelt, located ∼230 km north to the Hotan anticline, is controlled by both the upperdecóllement and the lower decóllement with the former ramping to the surface and thelatter building the Mazatagh anticline. The balanced cross-section reveals a totaldeformation of ∼28.93 km along this transect, with most deformation (∼25.0 km)transmitted by the upper decóllement among which at least 7.7 km of shortening hasbeen accommodated by the layer parallel compaction. The rest of shortening hasbeen absorbed by the Manan anticline (0.17 km) and the Mazatagh anticline (∼3.7km), respectively, transmitted along the lower decóllement. Our study highlightsthe effects of decóllement layer on transmitting deformation from the orogen intothe intracontinental region, the pre-existing structures on localizing distribution,and the penetrative strain on accommodating relatively homogeneous shortening. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau offers an ideal region for understanding the processes of continental collision and related intracontinental deformation. However, when the Cenozoic deformation was initiated in the present northeastern margin of the plateau, >2000 km north to the Indian-Eurasian collision front, remains an issue in debate. Two competing end-member models have been proposed, involving immediate deformation response and progressive deformation propagation. Solving this problem partly relies on determining whether there was contemporaneous deformation with initial Indian-Eurasian collision along the northeastern margin of the Tibetan Plateau. In this study, we employ apatite fission track (AFT) analysis to shed new light on the exhumation history of the Kuantan Shan-Hei Shan along the northeastern margin of the Tibetan Plateau, with a motivation to determine whether deformation-related exhumation during initial collision stage occurred in the region. The 22 granite samples produce AFT ages ranging from 22.3 ± 2.6 Ma to 175 ± 18 Ma and mean track lengths from 11.17 ± 2.26 μm to 13.63 ± 1.93 μm. Thermal history modeling indicates five episodes of rapid exhumation-related cooling, which took place in the early Jurassic, early Cretaceous and late Cretaceous, during/since the Eocene and since the middle Miocene. The exhumation events prior to the Cenozoic are attributed to far-field responses of successive closure of fossil oceans and assembly of blocks along the southern margin of the Eurasian continent. The Eocene exhumation along the Kuantan Shan-Hei Shan is speculated to represent an immediate response to the initial Indian-Eurasian collision. These results lend support to the immediate deformation response model along the northeastern plateau. The episodic exhumation observed in this study, combined with previous geophysical findings, implies that the Kuantan Shan-Hei Shan represents the southern margin of the Alashan Block, serving as a significant and long-lived lithospheric weak zone susceptible to intracontinental deformation during episodes of far-field tectonic event. • AFT analysis conducted in Kuantan Shan-Hei Shan at NE Tibetan Plateau margin • Eocene exhumation occurred in the Kuantan Shan-Hei Shan. • Data supports the immediate deformation response model. [ABSTRACT FROM AUTHOR]