Crustal anisotropy beneath northeastern Tibetan Plateau from the harmonic decomposition of receiver functions

Zhenxin Xie, Vadim Levin, Qingju Wu

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

A uniformly spaced linear transect through the northeastern Tibetan Plateau was constructed using 54 stations from ChinaArray Phase II. We used a set of colocated earthquakes to form receiver function beams that were then used to construct a 2-D image of main converting boundaries in our region and to investigate lateral changes in main impedance contrasts along the transect. The image revealed obvious mid-crustal low-velocity zones beneath the Qilian Orogen and the Alxa Block. We developed a new procedure that uses harmonically decomposed receiver functions to characterize seismic anisotropy, and that can determine both the orientations of symmetry axes and their type (fast or slow). We tested our technique on a number of synthetic models, and subsequently applied it to the data from the transect. We found that: (1) within the upper crust the orientations of slow symmetry axes are nearly orthogonal to the strike directions of faults, and thus anisotropy is likely caused by the shape preferred orientation of fluid-saturated cracks or fractures and (2) together with the low-velocity zones revealed from receiver functions stacks, anisotropic layers in the middle-to-lower crust could be explained by the crustal channel flow that was proposed for this region by previous studies. The shear within the boundary layers of crustal flow forms anisotropy with symmetry axes parallel to the flow direction.

Original languageEnglish (US)
Pages (from-to)1585-1603
Number of pages19
JournalGeophysical Journal International
Volume220
Issue number3
DOIs
StatePublished - Mar 1 2020

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology

Keywords

  • Asia
  • Crustal structure
  • Dynamics of lithosphere and mantle
  • Seismic anisotropy
  • Time-series analysis

Fingerprint

Dive into the research topics of 'Crustal anisotropy beneath northeastern Tibetan Plateau from the harmonic decomposition of receiver functions'. Together they form a unique fingerprint.

Cite this