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

Pei Zhang, Xiaodong Song, Jiangtao Li, Xingchen Wang, Xuezhen Zhang

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish (US)
Pages (from-to)93-106
Number of pages14
JournalEarthquake Science
Volume37
Issue number2
DOIs
StatePublished - Apr 2024
Externally publishedYes

Keywords

  • NE Qinghai-Xizang Plateau
  • crustal thickness
  • joint inversion
  • receiver functions
  • surface waves
  • v/v ratio

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Geophysics
  • Geology

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