青藏高原东南缘深部地球物理探测与壳幔结构研究进展  

Advances in the crust-mantle structure revealed by geophysical explorations in the southeastern margin of the Tibetan Plateau

作　　者：翁雪飞 武振波 徐涛[3,4] 唐国彬[3] 周卿 WENG XueFei;WU ZhenBo;XU Tao;TANG GuoBin;ZHOU Qing(Chengdu University of Technology,Key Laboratory of Earth Exploration and Information Techniques of the China Ministry of Education,Chengdu 610059,China;College of Geophysics,Chengdu University of Technology,Chengdu 610059,China;Key Laboratory of Mineral Resources,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Innovation Academy for Earth Science,CAS,Beijing 100029,China;Schlumberger China,Beijing 100015,China)

机构地区：[1]成都理工大学,地球探测与信息技术教育部重点实验室,成都610059 [2]成都理工大学地球物理学院,成都610059 [3]中国科学院地质与地球物理研究所,中国科学院矿产资源研究重点实验室,北京100029 [4]中国科学院地球科学研究院,北京100029 [5]斯伦贝谢科技服务(北京)有限公司,北京100015

出　　处：《地球物理学进展》2023年第2期612-630,共19页Progress in Geophysics

基　　金：国家自然科学基金(42174077,91755215)资助。

摘　　要：青藏高原东南缘地质构造作用复杂、地震活动频发,历来备受关注.为了探讨青藏高原周缘陆内变形动力学、高原侧向生长机制、地震孕育机理、大型矿床深部控矿模式等重要科学问题,地球物理学家已在该区域开展了大量的深部结构探测工作.本论文主要从人工源地震剖面、天然源地震成像、大地电磁剖面、地震各向异性等方面对该区域的研究结果进行了有效梳理和归纳总结,以期为后续的科学研究提供一定参考.综合来看,该区域地壳厚度整体呈现从南至北、从东向西逐渐增厚且地壳增厚主要发生在下地壳;区域内怒江断裂、南汀河断裂、无量山断裂、红河断裂等多条断裂均有切穿地壳的迹象;小江断裂至少延伸到下地壳,可能切穿地壳;腾冲火山区下方存在壳内低速、高导体,其上地幔也存在显著低速异常,深度约达300 km,壳内低速异常可能反映了未固结的岩浆囊,而深部地幔的低速则与印度板块在缅甸弧下方的东向俯冲有关;攀枝花地区地壳整体呈现地震波高速、介质高阻异常,表明其地壳介质的高强度特征;天然源地震学成像在青藏高原东南缘均发现在川西地块和小江断裂带附近存在明显的中下地壳低速异常,两者被攀枝花地区的高阻高速体隔开,并未直接连通,可能对应不同的成因机制;地震学观测到青藏高原东南缘上地壳各向异性的快波方向与GPS观测、地表构造存在一致性,但XKS得到的岩石圈地幔各向异性快波方向约在26°N附近存在明显的南北向分区性:其北侧主要为近N-S向,而南侧主要为近E-W向.The southeastern margin of the Tibetan Plateau has a complex geological structure and frequent seismic activities,which has always attracted much attention. In order to discuss important scientific issues in this region,such as the dynamics of intracontinental deformation around the Tibetan Plateau, the mechanism of lateral growth of the plateau, the tectonic environment of earthquake,and the deep tectonic process model to control large ore deposits,geophysicists have carried out a lot of deep structure exploration work. In this paper,based on the research results of active source seismic profile,passive source seismic imaging,magnetotelluric profile,and seismic anisotropy study,we sort out these research results and summarize common conclusions,in order to provide some references for the future study. The conclusions are as follows. The thickness of the crust in this region increases gradually from south to north and from east to west,and the crustal thickening mainly occurs in the lower crust. Several faults show signs of cutting through the crust, such as Nujiang fault, Nantinghe fault,Wuliangshan fault, Honghe fault. The Xiaojiang fault extends at least to the lower crust,and may reach the Moho.There are crustal low-velocity and high-conductivity anomalies under the Tengchong volcanic area,there are also low velocity in the upper mantle in the depth about300 km,the former may reflect the unconsolidated crustal magma,while the low velocity of the deep mantle is plausibly related to the eastward subduction of the Indian plate below the Burmese arc. The overall crust of the Panzhihua area presents high seismic wave velocity and high resistivity,indicating that the crustal medium has high strength. Passive seismic source imaging in the study area has found that there are obvious low-velocity anomalies in the middle and lower crust near the western Sichuan block and the Xiaojiang fault zone. They are not connected laterally, indicating different formation mechanisms. The fast wave direction of the upper crust in t

关 键 词：青藏高原东南缘 深部结构 地震学 大地电磁 各向异性 

分 类 号：P315[天文地球—地震学]