Seismic evidence of the Hainan mantle plume by receiver function analysis in southern China

Abstract

The Lei-Qiong region is the largest igneous province in southern China and may be a surface expression of a mantle plume beneath the region (the Hainan mantle plume). To investigate the existence of the Hainan mantle plume, we used P-to-S receiver function to image the major seismic discontinuities beneath this region with a regional dense broadband array. We found that the Moho discontinuity beneath the Leizhou Peninsula, mostly covered by Cenozoic basaltic outcrops, is 10–15 km deeper compared to the adjacent region of Eurasian continental margin, showing a thickened local crust by upwelling mantle materials. Additionally, the imaged 410- and 660-km discontinuities suggest a thinner-than-normal mantle transition zone beneath the region, implying that hot materials penetrate through the transition zone from the lower mantle. Both seismic evidences support the existence of the mantle plume, which might be 170–200°C hotter than the surrounding mantle.