Wedge tectonics in South China:constraints from new seismic data  

地震学观测揭示华南块体多期次拼合楔状特征

作　　者：Tingzi Li Mingming Jiang Liang Zhao Weihua Yao Ling Chen Yang Chu Baolu Sun Yinshuang Ai Bo Wan Klaus Gessner Huaiyu Yuan 栗婷姿;姜明明;赵亮;姚卫华;陈凌;褚杨;孙宝璐;艾印双;万博;Klaus Gessner;袁怀玉(State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Australian Research Council Centre of Excellence for Core to Crust Fluid Systems,Department of Earth and Environmental Sciences,Macquarie University,New South Wales 2109,Australia;Centre for Exploration Targeting,University of Western Australia,Crawley WA 6009,Australia;Key Laboratory of Earth and Plantenry Physics,Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Sciences,Beijing 100049,China;Guangdong Provincial Key Lab of Geodynamics and Geohazards,School of Earth Sciences and Engineering,Sun Yat-sen University,Guangzhou 510275,China;Geological Survey of Western Australia,Perth WA 6001,Australia)

机构地区：[1]State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [2]Australian Research Council Centre of Excellence for Core to Crust Fluid Systems,Department of Earth and Environmental Sciences,Macquarie University,New South Wales 2109,Australia [3]Centre for Exploration Targeting,University of Western Australia,Crawley WA 6009,Australia [4]Key Laboratory of Earth and Plantenry Physics,Chinese Academy of Sciences,Beijing 100029,China [5]University of Chinese Academy of Sciences,Beijing 100049,China [6]Guangdong Provincial Key Lab of Geodynamics and Geohazards,School of Earth Sciences and Engineering,Sun Yat-sen University,Guangzhou 510275,China [7]Geological Survey of Western Australia,Perth WA 6001,Australia

出　　处：《Science Bulletin》2022年第14期1496-1507,M0004,共13页科学通报（英文版）

基　　金：partially supported by the National Natural Science Foundation of China(91955210,41625016,and 41888101)。

摘　　要：Collisional orogens form when tectonic forces amalgamte fragments of Earth’s continental lithosphere.The sutures between individual fragments,or terranes,are potential sites of weakness that facilitate subsequent continental breakup.Therefore,the lithospheric architecture of collisional orogens provides key information for evaluating the long-term evolution of the continental interior:for example,the South China Block(SCB),where the tectonic history is severely obscured by extensive surface deformation,magmatism,and metamorphism.Using new passive-source seismic models,we show a contrasting seismic architecture across the SCB,with three prominent crustal dipping structures across the Jiangnan Orogen.Combined with constraints from multi-disciplinary regional geophysical datasets,these pronounced dipping patterns are interpreted as relict wedge-like lithospheric deformation zones initiated in the fossil collisions that assembled the Yangtze Block and the SCB.The overall trend of these tectonic wedges implies successive crustal growth along paleo-continental margins and is indicative of northward subduction and docking of accretional terranes.In contrast,no such dipping structures are preserved in the Cathaysia Block,indicating a weak and reorganized lithosphere.The variations in the deformation responses across the SCB reflect the long-term modifications of the lithosphere caused by prolonged collision and extension events throughout the tectonic history of the SCB.Our results demonstrate the critical roles that suture zones played in the successive growth and evolution of the continental lithosphere.大陆造山带形成于板块俯冲结束后大陆之间的碰撞,是研究大陆岩石圈长期演化的重要场所.华南块体的构造经历了多期的造山作用,但被广泛分布的地表形变和岩浆、变质作用所覆盖.本文利用横跨华南块体的超长密集流动台阵,获得了该地区高分辨率的浅部岩石圈地震结构,图像显示横跨江南造山带三个显著的中下地壳倾斜结构.综合区域地球物理资料,这些倾斜结构可归因于扬子克拉通内部以及华南块体拼合造山过程中岩石圈楔状变形.楔状构造的同向性指示了沿古大陆边缘幕式生长模式,并显示增生地体的持续北向碰撞与拼接.此外,华夏块体浅部岩石圈没有对应的碰撞变形残留,显示被改造的岩石圈结构特征.华南岩石圈结构鲜明的横向变化说明,早期碰撞构造的继承性控制了它的构造演化,体现了造山带在大陆岩石圈的稳定和活化过程中的重要作用.

关 键 词：Lithosphere architecture Seismic receiver functions Ambient noise tomography South China Block Wedge tectonics 

分 类 号：P315.7[天文地球—地震学]