Lithospheric Structure Near Jiuyishan, South China: Implications for Asthenospheric Upwelling and Lithospheric Modification

Abstract

AbstractIn this study, a high‐resolution 3D lithospheric S wave velocity model of the Jiuyishan region is constructed by joint inversion of receiver function and ambient noise. Our Moho depth model reveals relatively thick crust (∼35 km) beneath the Yangtze block and thin crust (∼27 km) beneath the Cathaysia block. The model depicts a complex boundary between these blocks, roughly following the Chenzhou‐Linwu fault in the northern part but gradually curving westward in the southern part between the two blocks. The 3D S wave velocity model shows low‐velocity anomalies in the middle crust, as well as in the upper mantle, interpreted as evidence of asthenospheric upwellings in the upper mantle. These upwellings modify lithosphere structures by changing their temperatures and compositions, and may provide a heat source through the Chenzhou‐Linwu fault for the low‐velocity anomaly in the shallow part beneath Jiuyishan region.