Complex deformation in western Tibet revealed by anisotropic tomography

Heng Zhang, Junmeng Zhao, Dapeng Zhao, Chunquan Yu, Hongbing Liu, Zhaoguo Hu

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

The mechanism and pattern of deformation beneath western Tibet are still an issue of debate. In this work we present 3-D P- and S-wave velocity tomography as well as P-wave radial and azimuthal anisotropy along the ANTILOPE-I profile and surrounding areas in western Tibet, which are determined by using a large number of P and S arrival-time data of local earthquakes and teleseismic events. Our results show that low-velocity (low-V) zones exist widely in the middle crust, whereas low-V zones are only visible in the lower crust beneath northwestern Tibet, indicating the existence of significant heterogeneities and complex flow there. In the upper mantle, a distinct low-V gap exists between the Indian and Asian plates. Considering the P- and S-wave tomography and P-wave azimuthal and radial anisotropy results, we interpret the gap to be caused mainly by shear heating. Depth-independent azimuthal anisotropy and high-velocity zones exist beneath the northern part of the study region, suggesting a vertically coherent deformation beneath the Tarim Basin. In contrast, tomographic and anisotropic features change with depth beneath the central and southern parts of the study region, which reflects depth-dependent (or decoupled) deformations there. At the northern edge of the Indian lithospheric mantle (ILM), P-wave azimuthal anisotropy shows a nearly east-west fast-velocity direction, suggesting that the ILM was re-built by mantle materials flowing to the north.

Original languageEnglish
Pages (from-to)97-107
Number of pages11
JournalEarth and Planetary Science Letters
Volume451
DOIs
Publication statusPublished - 2016 Oct 1

Keywords

  • Tibetan plateau
  • anisotropic tomography
  • crustal and uppermantle structures
  • diverse deformation patterns
  • lateral heterogeneities

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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