The lithospheric-scale deformation in NE Tibet from joint inversion of receiver function and surface wave dispersion

  • Joint inversion of dispersion and receiver function with specified Vp/Vs ratio
  • Positive correlation between average velocity in the crust and uppermost mantle
  • Diverse high mantle velocities in the north
Abstract

As a region far away from the Indian-Asian collision front, Northeastern (NE) Tibet has attracted great attention due to its implications for the plateau growth and the devastating earthquakes. Several geodynamic models have been proposed for the deformation mechanism of NE Tibet, but it remains controversial. Here we introduce the crustal Vp/Vs ratios from the H-k stacking to the joint inversion of receiver function and surface wave dispersion, which is based on the Neighborhood Algorithm. The crustal and uppermost mantle velocities are obtained beneath 203 stations in NE Tibet. The results show (1) deep Moho in Songpan-Ganzi and Qiangtang terranes, and distinct Moho depth between northwest and southeast Qilian; (2) positive correlation between the average velocity in the crust and in the uppermost mantle, suggesting a coupled lithospheric-scale deformation; (3) diverse high upper mantle velocities distributing in northern part of the study region, which may indicate the existing of local lithosphere or a non-uniform southward subduction of Asian lithosphere.

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