Lithospheric Structure in Central-East China from Joint Inversion of Surface-Wave Dispersion and CCP-Derived Receiver Function: Implications for Regional Tectonics

Abstract To investigate the lithospheric deformation beneath central-east China, we constructed a 3D crustal and uppermost-mantle velocity model of this region by joint inversion of Rayleigh-wave phase velocities and common conversion point-derived receiver functions. The velocity images at the east and west sides of Xuefeng Mountain presented quite different features and a sharp change in lithospheric thickness beneath this mountain, suggesting that this mountain may be the southwestern segment of the boundary between the Yangtze craton (YZC) and the Cathaysia block (CAB). We observed extensive lithospheric thinning in the eastern South China block (SCB), including the CAB and lower YZC. Considering that the eastern SCB is within the influence of the circum-Pacific system and features intensive Mesozoic magmatic activity, we deduced that subduction of the Pacific plate was the main controlling factor of lithospheric thinning. The westward extension of lithospheric thinning in the SCB terminates in the area east of the north–south gravity lineament. We observed a large-scale, low-velocity zone in the uppermost mantle of the southern Trans-North China orogen that penetrates northwestward into the southeastern corner of the Ordos block. The low-velocity zone intrudes into the bottom of the crust and results in crustal thinning in the region. We proposed that both the southern Trans-North China craton and the southeastern Ordos block are suffering ongoing lithospheric mantle modification.