首页|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
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
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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 ChinArray 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/vS structures 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/vS ratios. While, lower velocities and higher vP/vS ratios 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/vS ratios 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.
joint inversionreceiver functionssurface wavescrustal thicknessvP/vS ratioNE Qinghai-Xizang Plateau
Institute of Geophysics, China Earthquake Administration, Beijing 100081, China
The Second Monitoring and Application Center, China Earthquake Administration, Xi'an 710054, China
Institute of Theoretical and Applied Geophysics, School of Earth and Space Sciences, Peking University, Beijing 100871, China
Department of Geophysics, School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China
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Natural Science Basic Research Program of ShaanxiSpecial Fund of the Institute of Geophysics,China Earthquake AdministrationNational Natural Science Foundation of China
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