1. ∼ 15 Ma thrusting along the North Altyn Fault: implications for Mid-Miocene reorganization of the Altyn Tagh fault system, northeastern Tibetan Plateau.
- Author
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Gao, Shibao, Cheng, Xiaogan, Lin, Xiubin, Wu, Lei, Yang, Rong, Chen, Hanlin, Yang, Shufeng, and Song, Xingtong
- Subjects
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CENOZOIC Era , *PLATEAUS , *THRUST faults (Geology) , *LASER ablation inductively coupled plasma mass spectrometry , *TECTONIC exhumation , *THRUST - Abstract
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]
- Published
- 2019