Crustal and uppermost mantle structure of the northeastern Qinghai-Xizang Plateau from joint inversion of surface wave dispersions and receiver functions with P velocity constraints  

作　　者：Pei Zhang Xiaodong Song Jiangtao Li Xingchen Wang Xuezhen Zhang 

机构地区：[1]Institute of Geophysics,China Earthquake Administration,Beijing 100081,China [2]The Second Monitoring and Application Center,China Earthquake Administration,Xi'an 710054,China [3]Institute of Theoretical and Applied Geophysics,School of Earth and Space Sciences,Peking University,Beijing 100871,China [4]Department of Geophysics,School of Geodesy and Geomatics,Wuhan University,Wuhan 430079,China

出　　处：《Earthquake Science》2024年第2期93-106,共14页地震学报（英文版）

基　　金：supported by the Natural Science Basic Research Program of Shaanxi(No.2023-JC-QN-0306);the Special Fund of the Institute of Geophysics,China Earthquake Administration(No.DQJB21B32);the National Natural Science Foundation of China(No.42174069).

摘　　要：Lithospheric structure beneath the northeastern Qinghai-Xizang Plateau is of vital significance for studying the geodynamic processes of crustal thickening and expansion of the Qinghai-Xizang Plateau. We conducted a joint inversion of receiver functions and surface wave dispersions with P-wave velocity constraints using data from the Chin Array Ⅱ temporary stations deployed across the Qinghai-Xizang Plateau. Prior to joint inversion, we applied the H-κ-c method(Li JT et al., 2019) to the receiver function data in order to correct for the back-azimuthal variations in the arrival times of Ps phases and crustal multiples caused by crustal anisotropy and dipping interfaces. High-resolution images of vS, crustal thickness, and vP/vSstructures in the Qinghai-Xizang Plateau were simultaneously derived from the joint inversion. The seismic images reveal that crustal thickness decreases outward from the Qinghai-Xizang Plateau. The stable interiors of the Ordos and Alxa blocks exhibited higher velocities and lower crustal vP/vSratios. While, lower velocities and higher vP/vSratios were observed beneath the Qilian Orogen and Songpan-Ganzi terrane(SPGZ), which are geologically active and mechanically weak, especially in the mid-lower crust.Delamination or thermal erosion of the lithosphere triggered by hot asthenospheric flow contributes to the observed uppermost mantle low-velocity zones(LVZs) in the SPGZ. The crustal thickness, vS, and vP/vSratios suggest that whole lithospheric shortening is a plausible mechanism for crustal thickening in the Qinghai-Xizang Plateau, supporting the idea of coupled lithospheric-scale deformation in this region.

关 键 词：joint inversion receiver functions surface waves crustal thickness vP/vS ratio NE Qinghai-Xizang Plateau 

分 类 号：P631.4[天文地球—地质矿产勘探]