Mantle Transition Zone Structure Beneath Hainan and Adjacent Areas Derived from Receiver Function Analysis

Abstract We have determined the upper mantle 410 km discontinuity and 660 km discontinuity structure and transition zone thickness beneath Hainan and adjacent areas by using receiver function method. The data used in this study are teleseismic waveforms recorded by 88 seismic stations in Hainan, Guangdong and Guangxi Regional Seismic Network and National Seismic Network during August, 2007 to March, 2010. The results show that the structure of 410 km discontinuity is complex below this region, which is depressed to 447 km locally. The 660 km discontinuity is simple relatively, with the depth around 670 km. The transition zone is thinned anomalously by 25±5 km within an area approximately 200 km in diameter centered northeast of the Hainan island, consistent with an excess temperature of ~180°C. The locally thinned transition zone implies that the Hainan plume originates from lower mantle.