1.中国科学院地质与地球物理研究所岩石圈演化国家重点实验室 北京 100029； 2.Institue des Sciences de la Terre dOrléans|Campus Géosciences|Université dOrléans| 1A Rue de la Férollerie| 45071 Orléans Cedex 2|France； 3.中国科学院研究生院 北京 100049
Tectonic evolution of the Early Mesozoic Xuefengshan belt: Insights from structural analysis and geochronological constraints
Chu Yang1|2|3 Lin Wei1 FaureMichel2 Wang Qingchen1
1.State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029;2.Institute des Sciences de la Terre d'Orleans,Campus Geosciences,Universite d'Orleans,1A Rue de la Ferollerie,45071 Orleans Cedex 2,France;3.Graduate University of Chinese Academy of Sciences,Beijing 100049
In the center of the South China Block，in Hunan Province，the Xuefengshan Belt provides a wellexposed example of intracontinental orogens.Detail field observations indicate that the Xuefengshan Belt can be divided into：(1)the Western Outer Zone，characterized by kmscale boxfold structure； (2)the Central Xuefengshan Zone，where the dip of the cleavage surface exhibits a fanlike pattern，separated from the Western Outer Zone by the Xuefengshan Main Thrust，the most deformed and metamorphosed region in this belt； (3)and the Eastern Zone，deformed mainly in the brittleductile level，characterized by toptotheNW structures and also some backfolding structures.The Xuefengshan Belt results of polyphase deformation：D1，characterized by a widespread toptotheNW ductile shearing.D2 corresponds to a SEdirected back thrusting and folding event.D3 consists of upright folds with vertical cleavage and lineation.The tectonic evolution of the Early Mesozoic Xuefengshan Belt is possibly originated by the continental subduction in response to the northwest directed subduction of the Pacific plate.