Upper mantle structure and dynamics beneath Southeast China

Abstract

We applied teleseismic tomography to 5671 relative travel-time residuals from 257 teleseismic events recorded by 69 seismic stations to determine the 3D P-wave velocity structure of the upper mantle under Southeast (SE) China. Our results show prominent low P-wave velocity (low-Vp) anomalies under SE China which may reflect the remnant magma chambers and channels of the Late Mesozoic igneous rocks, which may be reheated by the upwelling mantle flow from the lower mantle driven by the deep subduction in East Asia during the Cenozoic. High-Vp anomalies are revealed in the upper mantle to the east of Taiwan, which represent the subducted Eurasian plate. Our result also suggests the break-off of the subducted Eurasian plate caused by its interaction with the Philippine Sea plate under Central and North Taiwan. The slab break-off may have created a mantle window through which the asthenospheric flow arises, causing the high heat flow and rapid uplift in the Taiwan orogen.