Crustal and upper mantle velocity structure beneath central Tibet by P-wave teleseismic tomography

Abstract

SUMMARY A detailed 3-D P-wave velocity model beneath central Tibet was obtained using 26 741 arrival times from 1025 teleseismic events recorded by the portable stations of the Hi-CLIMB project. In the crustal correction, we consider both vertical and lateral velocity variations. Our teleseismic P-wave tomography result reveals that the Indian lithospheric mantle underthrusts no further than 32.5°N. In addition, the presence of low velocity anomalies under the Indus-Tsangpo suture suggests that subduction is not a simple and continuous process. We suggest that the delamination of Indian mantle lithosphere induces mantle upwelling beneath the rifts, which in turn created cracks or a break in the subducted plate. Moreover, the formation of active rifts near the profile is related to the mantle upwelling.