The upper mantle discontinuity structure beneath eastern China

We apply a common conversion point stacking technique of receiver functions from the North China Interior Structure Project (NCISP) to image the upper mantle discontinuity structure beneath eastern China. The stacking results of dense receiver functions reveal a prominent discontinuity structure. The appearance of the 410-km discontinuity is sharp and consistent with little influence by Western Pacific subduction slabs. The 520-km discontinuity is relatively weak and consists of splitting phases at depths ranging from 500 km to 550 km. As for the 660-km discontinuity, double discontinuities and a narrow depression zone are detected near a depth of 660-km, indicating a more complex structure there. Phase transformations in non-olivine components, such as from garnet to perovskite, seem to be a more plausible interpretation for a complex 660-km discontinuity in this region.