联合多源数据反演郯庐断裂带南段地壳三维速度结构  

Three-dimensional crustal velocity structure beneath the southern segment of the Tan-Lu fault revealed by joint inversion from multi-source data

作　　者：张云鹏[1,2] 王伟涛 杨微[1,2] 刘影 ZHANG YunPeng;WANG WeiTao;YANG Wei;LIU Ying(Institute of Geophysics,China Earthquake Administration,Beijing100081,China;Key Laboratory of Earthquake Source Physics,China Earthquake Administration,Beijing100081,China;School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China)

机构地区：[1]中国地震局地球物理研究所,北京100081 [2]中国地震局震源物理重点实验室,北京100081 [3]中国科学技术大学地球和空间科学学院,合肥230026

出　　处：《地球物理学报》2023年第6期2404-2419,共16页Chinese Journal of Geophysics

基　　金：中国地震局地球物理研究所基本科研业务费专项(DQJB22Z01);中国地震局地球物理研究所基本科研业务费专项(DQJB20K36)联合资助;国家自然科学基金(41790464,42104045,41790463)。

摘　　要：郯庐断裂带南段位于不同块体交汇区,高分辨率的地壳速度结构有助于理解该地区的构造特征及成因.本文基于多源数据,利用2015年安徽实验中气枪的体波和高频面波,2008—2018年区域地震体波信号以及背景噪声面波频散等资料,将不同来源、不同周期的面波频散数据和体波走时进行联合反演,获取了郯庐断裂带南段的高精度地壳速度结构.研究结果表明:(1)加入面波信息进行联合反演后,获取的P波和S波速度模型的分辨能力较单一体波数据反演在中下地壳均有显著提升.(2)郯庐断裂带是控制区域异常的主要因素,两侧具有明显的速度差异.地震主要发生在断层附近,集中分布于高低速交界区.(3)秦岭—大别造山带下方5~10 km深度存在明显的高速异常体,对应于超高压变质岩,是大陆深俯冲经历超高压变质作用后折返上升到中上地壳形成的.(4)长江中下游成矿带的矿集区呈现高的P波和S波速度值,可能是陆内俯冲、岩石圈拆沉、幔源岩浆底侵和一系列成矿作用共同造就的.The southern segment of the Tan-Lu fault zone is located in the intersection of different blocks,high-resolution crustal velocity structure is helpful to understand the structural characteristics and formation mechanisms in this region.Based on the body wave signals and high-frequency surface wave signals from the Anhui Airgun Experiment in 2015,the body wave signals of regional earthquakes from 2008to 2018,and the surface wave dispersion of ambient noise,we jointly inverted the surface wave dispersion data and body wave travel times from different sources and different periods to obtain the high-precision crustal VPand VSstructure beneath the southern segment of the Tan-Lu fault zone.The results show that:(1)By adding surface wave data for joint inversion,the resolution capability of the obtained P-wave and S-wave velocity models in the middle and lower crust is significantly improved compared with inversion results using single body wave data.(2)Large velocity contrasts are observed across the Tan-Lu fault zone,which is the main factor controlling local geophysical/geological anomalies.Earthquakes are primarily concentrated near faults and are mostly located in areas with high-and low-VPand VSanomalies.(3)There are high velocity bodies beneath the Qinling-Dabie Orogenic Belt(QDOB),corresponding to the ultra-high-pressure metamorphic rocks,which are formed by the uplifting and exhumation of the deep subducted continent after undergoing ultra-high-pressure metamorphism.(4)The ore deposits beneath the Middle-Lower Yangtze River Metallogenic Belt(MLYRMB)present high P-wave and S-wave values,which may be formed by intracontinental subduction,lithosphere delamination,mantle-derived magmatic underplating and mineralization.

关 键 词：郯庐断裂带南段 气枪震源 体波和面波联合反演 地壳速度结构 

分 类 号：P315[天文地球—地震学]