S波接收函数揭示的华南陆块岩石圈结构及构造启示  

The Lithosphere Structure of South China Block Revealed by S-wave Receiver Function Analysis and Its Tectonic Implications

作　　者：沈旭章 陈萌萌 程思远 王岳军 黄斯燃 SHEN Xuzhang;CHEN Mengmeng;CHENG Siyuan;WANG Yuejun;HUANG Siran(Guangdong Provincial Key Laboratory of Geodynamics and Geohazards,School of Earth Sciences and Engineering,Sun Yat-sen University,Zhuhai 519082,Guangdong,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519082,Guangdong,China)

机构地区：[1]中山大学地球科学与工程学院,广东省地球动力作用与地质灾害重点实验室,广东珠海519082 [2]南方海洋科学与工程广东省实验室(珠海),广东珠海519082

出　　处：《大地构造与成矿学》2024年第3期410-419,共10页Geotectonica et Metallogenia

基　　金：国家自然科学基金项目(42230305);第二次青藏高原综合科学考察研究项目(2019QZKK0701);广东省引进创新研发团队项目(2017ZT07Z066)联合资助。

摘　　要：本研究利用华南陆块固定地震台站记录到的远震地震波资料,构建适合研究LAB的S波接收函数,基于接收函数波形分析和偏移成像结果对华南陆块岩石圈性质进行了研究。结果显示华南陆块下方70 km深度存在最明显且连续性相对较好的低速界面,结合其他地球物理研究成果,我们认为70 km深度低速界面反映了和软流圈上涌相关的构造事件导致的华南岩石圈大规模减薄;在华夏地块的东部较大范围探测到100~150 km深度内存在南倾的低速界面,结合区域岩石学、地球化学和地质学等研究成果,推测该现象可能表明扬子地块的岩石圈楔入到了华夏地块,是新元古代早‒中期以来,华南陆块俯冲聚合、陆内造山以及陆内构造变形等地球动力学事件留下的重要痕迹;在华夏地块中东部和江南造山带局部发现了LAB缺失区带,该现象可能与岩石圈拆沉导致的热物质上涌密切相关,可能对应了地块拼贴薄弱带。The structure and deformation features of the lithosphere are important information for studying the interactions between blocks,especially the exploration of the lithosphere-asthenosphere boundary(LAB),and its tectonic implications have always been a hot topic in scientific research.The South China Block has undergone complex tectonic processes and traces of different tectonic events have been retained in the lithosphere.Therefore,the lithospheric structure of the South China Block is critically significant for understanding its tectonic evolution dynamics.The body wave receiving function is one of the most effective seismological methods for LAB detection.Although the P-wave receiver function method is simple and provides stable results,there may be shallow interface multiple wave interference in the depth range of LAB.Because there is no multiple wave interference in the LAB depth range,S-wave receiver function is the most commonly used seismological method in LAB study.Due to the complexity of S-wave and the influence of P-wave scattering,the repeatability of S-wave receiver function results is poor,which also reduces the reliability of the results.Through waveform analysis,a method for constructing S-wave receiving functions suitable for LAB research was proposed in our previous work.In this study,the S-wave receiving functions were calculated from the data of teleseismic waves recorded by permanent seismic stations in the South China Block.Based on waveform analysis and CCP stacking images of the receiving function,the lithospheric properties of the South China massif are discussed.Our results show that there is an obvious and relatively good continuous low-velocity interface at a depth of 70 km below the South China Block.Combined with other geophysical research results,it can be inferred that the low-velocity interface at 70 km depth reflects the massive thinning of the South China lithosphere caused by tectonic events related to asthenosphere upwelling.A low-velocity south-dipping interface at a depth of

关 键 词：华南陆块 LAB 地震波 S波接收函数 岩石圈拆沉 

分 类 号：P315[天文地球—地震学]