Mid-Miocene (17-11 Ma) Fast Exhumation in the Upper Jinsha River and its Implication for Regional Faulting in Southeast Tibet

作     者：Shen, Xuwen Liu-Zeng, Jing Shen, Xiaoming Ge, Yukui Zeng, Xianyang Wang, Zijun Xing, Yukun Wang, Heng 

作者机构：School of Earth System Science Tianjin University Tianjin300072 China National Institute of Natural Hazards Ministry of Emergency Management of China Beijing100085 China State Key Laboratory of Earthquake Dynamics Institute of Geology China Earthquake Administration Beijing100029 China School of Geography Earth and Atmospheric Sciences University of Melbourne VIC3010 Australia 

出 版 物：《SSRN》 

年 卷 期：2023年

核心收录：

主　　题：Rivers 

摘      要：The rugged southeast (SE) Tibet hosts a network of evolving faults, many of which are poorly understood due to a lack of sedimentary records and poor accessibility. The Jinsha River fault zone (JRFZ) is vaguely considered as a major fault bounding the Chuan-Dian Block in the northwest, yet little is known about its tectonic evolution history, which hinders our clear understanding of the tectonic deformation pattern, process and geomorphic response of SE Tibet. Here, we collected 10 samples from the hanging wall of the Xiongsong reverse fault, one strand of the JRFZ, near Markam area and on the trunk of the upper Jinsha River, to reveal its exhumation and kinematic history through low-temperature thermochronology. The ZHe ages (~17-13 Ma) of the samples from the hanging wall are much younger than the published ones in the footwall, but the AFT (~11-9 Ma) and AHe ages (~14-6 Ma) are only slightly younger than those in the footwall. The QTQt and 3-D thermo-kinematic Pecube modeling suggest consistently that the Xiongsong fault experienced strong activity during the mid-Miocene (~17-11 Ma) and then weakened. Post-11 Ma decreases in exhumation here on the trunk of the Jinsha river, if interpreted as river incision, is opposite to previously inferred river response to late Miocene surface uplift driven by the lower crust flow, implying the importance of local faulting in regional exhumation and perhaps the development of the Jinsha River. The late Miocene transition of faulting activity is found on other major faults in SE Tibet as well. We infer that the near synchronized change in regional fault activity may be caused by the clockwise rotation of the Chuan-Dian block, while its being extruded southeastward from the pushing front of the Indian collision. © 2023, The Authors. All rights reserved.