Zircon U-Pb Geochronology of the Cenozoic Granitic Mylonite along the Ailaoshan-Red River Shear Zone:New Constraints on the Timing of the Sinistral Shearing

作     者：Xiaofei Guo Yuejun Wang Huichuan Liu Jianwei Zi 

作者机构：State Key Laboratory of Isotope GeochemistryGuangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China University of Chinese Academy of SciencesBeijing 100049China School of Earth Science and Geological EngineeringSun Yat-sen UniversityGuangzhou 510275China CAS Center for Excellence in Tibetan Plateau Earth SciencesBeijing 100101China School of Earth and EnvironmentUniversity of Western AustraliaCrawley 510275Western Australia 

出 版 物：《Journal of Earth Science》 (地球科学学刊（英文版）)

年 卷 期：2016年第27卷第3期

页      面：435-443页

核心收录：

学科分类：070902[理学-地球化学] 0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学] 

基　　金：Supported by the National Basic Research Program of China(No.2014CB440901) the China National Natural Science Foundation(No.41190073) the Fundamental Research Funds for the Central Universities to SYSU 

主　　题：Ailaoshan-Red River zircon U-Pb dating mylonite and migmatite sinistral shearing eastward extrusion 

摘      要：The Ailaoshan-Red River（ASRR） shear zone in SW China represents an important discontinuity believed to have accommodated eastward extrusion of the Tibetan Plateau in response to the collision of the Indian and Eurasian plates. The onset timing and duration of the ASRR sinistral strike-slip shearing have been hotly disputed. In this paper we present new zircon LA-ICP-MS U-Pb geochronological data from six syntectonic granitic mylonite and leucosomes samples from the ASRR shear zone. Our data reveal a metamorphic age of ~40 Ma, most likely suggesting the maximum age of the shearing initiation. Rocks showing syn-kinematic signatures yield crystallization ages of 38–22 Ma, with inherited components ranging from 716 to 108 Ma. These results, together with existing geological and geochronological data, indicate that the sinistral shearing along the ASRR zone probably began at 40 Ma, mainly activated at 29–22 Ma and lasted at least to ~22 Ma. Our data suggest a continuous extrusion between the Indochina and South China blocks during ~35–17 Ma. The ASRR sinistral shearing has accommodated large scale eastward displacement of the southeastern Tibetan syntaxis, and is likely responsible for the opening of the South China Sea.