Radially anisotropic S-wave velocity structure of the upper mantle beneath NE China

The causes of intraplate volcanoes in northeastern China and, in particular, how asthenospheric upwelling interacts with the lithosphere remain poorly constrained. In this study, we use teleseismic data to measure the phase and group velocities of Rayleigh and Love waves, and invert for the shear wave velocity and radial anisotropy within the crust and uppermost mantle. Our results show that there are significant low-velocity anomalies and negative radial anisotropy to the northeast of Changbaishan, suggesting an asthenospheric melt reservoir. This is underlain by mantle upwelling, with regional lithospheric structure focusing melt beneath the volcano. In addition, our results show a high-velocity body in the mantle beneath the southwestern Songliao Basin. This exhibits negative radial anisotropy at its margins, suggesting vertical flow. We suggest that lithospheric delamination here may drive intraplate volcanism beneath the Great Xing'an range.