Crustal and Upper-mantle Structure of Southeastern Tibetan Plateau Inverted by Joining Surface Wave Dispersion and Receiver Function

Abstract:

The geological infrastructure of the southeastern edge of Tibetan Plateau involves in the understanding of the mechanisms of local strong earthquakes and tectonic and geodynamics. In the present study, we construct a high-resolution 3D shear-wave velocity (V_s) model through joint inversion of receiver functions (RFs) and surface wave dispersion (SWD) data. In each station, the fundamental dispersion mode data of Rayleigh waves are inverted into shear-wave profile. The crustal thickness structure and Poisson’s ratio model are constructed by H-K stacking of RFs, rather than pre-determined. The inverted crustal thicknesses changes from 30 km in the south to 62 km in the north, showing strong lateral variations and matching well with the tomography in mirror symmetry. The inverted V_s structure varies laterally too. There are low velocity zones (LVZs) distribute at the crust and upper mantle. Both LVZs extend from the northern Yunnan towards southeast and southwest, respectively, and then separate at the southern Yunnan. These two LVZs possibly present two flowing channels of crustal and upper mantle materials at the Southeastern Tibetan Plateau.

Keywords: Tibetan Plateau; joint analysis; crustal flow; receiver function; surface wave dispersion