Hainan mantle plume (Le-Muse)

The Hainan mantle plume has been proposed to explain the largest igneous province in Lei-Qiong region of southern China. We analyzed the data from regional broadband seismic stations using the receiver function method to study the seismic constrains of this plume. The shear wave velocity structures indicate high velocity anomalies in the upper crust and low velocity anomalies in the lower crust beneath the Leizhou Peninsula. This is the consequence of the eruption/intrusion of the mafic rocks in the upper crust and the partial melting in the lower crust. The migration images for the shallow structure of Lei-Qiong region show significant depression of the Moho discontinuity beneath the Leizhou Peninsula, where the Cenozoic basalt mostly outcropped, which is about 15 km deeper than that beneath the adjacent South China block and Hainan Island. This is consistent with the existence of the mantle plume as the up-welling mantle materials thickened the crust of Leizhou Peninsula. In addition, the migration imaging for the upper mantle shows a thinner transition zone (with the top boundary at 425 km depth and the bottom boundary at 650 km depth) beneath the Lei-Qiong region, which indicates the temperature is higher by ~ 200 ˚C than the surrounding mantle.

In order to provide detailed information for the crust and upper mantle beneath the Lei-Qiong region, we operated a temporary PKU Le-Muse Array over the entire Leizhou Peninsula and adjacent areas. Six-month data from the permanent stations of the Hainan Seismological Bureau, CEA were also used in our study.

Portable seismic stations of the PKU Le-Muse Array operated between Feb. 2008 and Apr. 2009 (red) and permanent stations of the Hainan Seismological Bureau, CEA (blue).