Receiver function analysis of crustal structure beneath the eastern Tibetan plateau

Abstract

We measure the crustal structure beneath the eastern Tibetan plateau by analyzing three-component teleseismic data recorded at 252 stations from January 1, 2008 to March 31, 2011. Lateral variations of the crustal thickness and Poisson’s ratio are obtained by using receiver function method. The thinnest crust is ∼27km in the south Yangtze craton and the deepest Moho (∼70km) is estimated in the eastern margin of the Tibetan plateau. The distribution of Poisson’s ratio shows the heterogeneity that high Poisson’s ratios (υ>0.27) are found in the Chuandian plateau, intermediate values (0.24⩽υ⩽0.27) exhibit in the Ordos block, the Qilian orogen, the Qinling–Dabie orogen, the Songpan-Ganzi terrane and the Sichuan basin, and low values (υ<0.24) appear in the Yangtze craton. The higher Poisson’s ratios (υ>0.30) in the southeastern margin of the Tibetan plateau can be considered as the evidence of the dominantly mafic composition or locally partial melting in crust. Our observations of the crustal thickness and Poisson’s ratio beneath the eastern Tibetan plateau not only reveal the lateral inhomogeneity of the crustal structure, but also provide some constraints on the mechanism of uplift and crustal thickening of the Tibetan plateau.