Dabie-Sulu orogenic belt is an important collisional mountain belt in eastern China.Detailed lithospheric velocity model is essential for better comprehension of the tectonic evolution and geodynamic processes in this region.The earthquake catalog data recorded by the China Digital Seismic Network from 2008 to 2021 are collected in this study,including the waveform data of 103 self-managed stations in Jiangsu,Anhui and Henan provinces.We also assembled the Rayleigh surface wave dispersion data for the period of 8～70 s in this area,and the joint inversion method of body wave and surface wave data is employed to determine the Vp and Vs models with horizontal grid intervals of 0.5°×0.5°.Additionally,the earthquakes were relocated by joint inversion.This research obtained the following results:(1)The crustal velocity models in Dabie and Sulu orogenic belts exhibit a similar pattern of convex upwards and concave downwards.Both high and low-velocity anomalies exist in the middle crust,but the lithosphere thickness of the Sulu orogen is relatively thinner.(2)The lithospheric mantle gaps on the south side of the Xiangfan-Guangji fault,the Xiaotian-Mozitan fault and the Jiashan-Xiangshui fault are likely related to the lithosphere delamination.We suggest that the high-velocity anomalies in the middle crust probably are the products of crystallization of upwelling mantle materials through the lithosphere weak zones.(3)The Dabie Mountain and the Sulu terrane may have shared a common tectonic origin,yet the differences in their current lithospheric mantle could result from the subduction of the Yangtze plate,the strike-slip motion of the Tan-Lu fault zone,and the subduction of the Paleo-Pacific plate.(4)Main geological bodies show distinct seismic activities,with a general trend of higher seismicity in the north than in the south,and earthquakes mainly occur in the transition zone between high and low velocities or in high velocity anomaly areas.The earthquakes beneath Tancheng in the central segment of Tan-Lu fault zone are distributed in high-angle stripes,with maximum hypocenteral depth around 25 km,indicating that the fault may have high dip angle in the deep part.
关键词
大别—苏鲁造山带/体波面波联合反演/岩石圈三维速度结构/郯庐断裂带中南段/地震重定位
Key words
Dabie-Sulu orogenic belt/Joint inversion of body wave and surface wave data/Three-dimensional lithospheric velocity structure/Central south segment of Tan-Lu fault zone/Earthquake relocation
维普
万方数据