The Structure of the crust and uppermost mantle in China from ambient noise tomography

In recent years, a large-scale array of broadband seismographs, so-called China National Seismic Network (CNSN), has been burgeoning across China. This large scale array provides unprecedented opportunities to image lithospheric structures of China at unprecedented resolution. Based on 1-2 years of continuous seismic ambient noise data recorded at more than 600 stations from CNSN and several other temporary arrays across China, A 3-D Vsv model of the crust and uppermost mantle is constructed. The 3-D model exhibits significant apparently inter-connected low shearvelocity features across most of the Tibetan middle crust at depths between 20 and 40 km, most prominent nearthe periphery of Tibet. The prominent LVZs are coincident with strong mid-crustal radial anisotropy in western and central Tibet and probably result partially from anisotropic minerals aligned by deformation, which mitigates the need to invoke partial melt to explain the LVZ observations. The western Yangtze Craton are characterized by relatively thick crust (40 km) overlying a high seismic mantle lithosphere that extends to at least 150 km that may have been the nucleus of formation forthe Yangtze craton in the Archean and presents a present-day obstacle to the eastward expansion of Tibet. The West Yangtze Block contrasts with the thinner crust (30 km) and mantle lithosphere (70-80 km) beneath the eastern Yangtze Craton and South China Foldbelt. Very thin, attenuated lithosphere bounds three sides of the eastern North China Craton (NCC), but somewhat thicker faster lithosphere underlies the central and southern parts of the eastern NCC.