Teleseismic P-wave tomography and mantle dynamics beneath Eastern Tibet

Jianshe Lei, Dapeng Zhao

Research output: Contribution to journalArticle

78 Citations (Scopus)

Abstract

We determined a new 3-D P-wave velocity model of the upper mantle beneath eastern Tibet using 112,613 high-quality arrival-time data collected from teleseismic seismograms recorded by a new portable seismic array in Yunnan and permanent networks in southwestern China. Our results provide new insights into the mantle structure and dynamics of eastern Tibet. High-velocity (high-V) anomalies are revealed down to 200 km depth under the Sichuan basin and the Ordos and Alashan blocks. Low-velocity (low-V) anomalies are imaged in the upper mantle under the Kunlun-Qilian and Qinling fold zones, and the Songpan-Ganzi, Qiangtang, Lhasa and Chuan-Dian diamond blocks, suggesting that eastward moving low-V materials are extruded to eastern China after the obstruction by the Sichuan basin, and the Ordos and Alashan blocks. Furthermore, the extent and thickness of these low-V anomalies are correlated with the surface topography, suggesting that the uplift of eastern Tibet could be partially related to these low-V materials having a higher temperature and strong positive buoyancy. In the mantle transition zone (MTZ), broad high-V anomalies are visible from the Burma arc northward to the Kunlun fault and eastward to the Xiaojiang fault, and they are connected upward with the Wadati-Benioff seismic zone. These results suggest that the subducted Indian slab has traveled horizontally for a long distance after it descended into the MTZ, and return corner flow and deep slab dehydration have contributed to forming the low-V anomalies in the big mantle wedge. Our results shed new light on the dynamics of the eastern Tibetan plateau.

Original languageEnglish
Pages (from-to)1861-1884
Number of pages24
JournalGeochemistry, Geophysics, Geosystems
Volume17
Issue number5
DOIs
Publication statusPublished - 2016 May 1

Keywords

  • Chinese provincial networks
  • Eastern Tibetan plateau
  • mantle dynamics
  • portable seismic array
  • teleseismic tomography

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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