Early Mesozoic tectonics of the South China block:Insights from the Xuefengshan intracontinental orogen
作者单位：State Key Laboratory of Lithospheric EvolutionInstitute of Geology and GeophysicsChinese Academy of Sciences Institut des Sciences de la Terre d'OrleansCampus GeosciencesUniversite d'Orleans
会议名称：《中国科学院地质与地球物理研究所2012年度（第12届）学术年会》
会议日期：2013年
学科分类：070904[理学-构造地质学] 0709[理学-地质学] 07[理学]
基 金：funded by the Innovative Project of the Chinese Academy of Sciences(Grant No.KZCX1-YW-15-1) Major State Basic Research Development Program of China (2005CB422101,2009CB825008) NSFC Grant Nos.90714007 and 40730315
关 键 词：Intracontinental orogen Fold-and-thrust belt Xuefengshan Belt South China block Early Mcsozoic orogeny
摘 要：Intracontinental orogens remain less understood than accretionary or collisional orogens that are related to plate margin *** the center of the South China block,the Xuefengshan Belt provides a well-exposed example of such an intracontinental orogen of Early Mesozoic *** field tectonic observations indicate that the Xuefengshan Belt can be divided into a Western Outer Zone characterized by km-scale box-fold structures,and an Eastern Zone,separated from the Western Outer Zone by the SE-dipping Main Xuefengshan *** the Eastern Zone,NW verging folds coeval with a pervasive slaty cleavage and a NW-SE trending lineation are the dominant *** west to east,the dip of the cleavage surface exhibits a fan-like *** bulk architecture of the Xuefengshan Belt results from polyphase deformation:D is characterized by a top-to-the-NW ductile shearing;D corresponds to SE-directed back thrusting and folding;D consists of upright folds with vertical cleavage and lineation. At depth,a high strain zone characterized by greenschist facies metamorphic rocks and a top-to-the-NW ductile shearing corresponds to a ductile decollement zone that accommodated the deformation of the Neoproterozoic to Early Triassic sedimentary *** compatibility suggests that the synmetamorphic ductile shearing was coeval with the D event in the sedimentary *** Xuefengshan Belt is interpreted as an Early Mesozoic intracontinental orogen,which possibly originated from the SE-directed continental subduction of a piece of the South China block in response to northwestwards subduction of the Pacific plate.