Mantle Upwelling Beneath the Cathaysia Block, South China

Abstract

AbstractA large low‐velocity anomaly (LLVA) beneath the Cathaysia Block in South China that may be associated with mantle upwelling was revealed by seismic tomography. However, seismological and geological studies indicate that ascending mantle must have a higher temperature than the surrounding mantle, and a low‐velocity anomaly alone is not indicative of mantle upwelling. The receiver function technique has been used as a robust tool to characterize the topographic relief of the upper mantle discontinuities, which are closely related to temperature variations and mantle upwelling. In this study, we extracted 25,187 receiver functions and performed common‐conversion‐point stacking of those receiver functions in South China and across the location of the LLVA beneath the Cathaysia Block. The results show that the 410 km discontinuity is depressed and that the 660 km discontinuity is elevated at the location of the LLVA. The structure of the mantle transition zone seems to be the passage of an upwelling mantle plume, which implies that the LLVA is a signature of mantle upwelling.