Oceanic mantle gravimetric response to the seafloor spreading of the Southwest Sub‐basin, South China Sea

Abstract

AbstractThe residual mantle gravity anomaly (RMA) is a straightforward response of the deep mantle structure of the lithosphere. We acquired RMA from newly updated free‐air gravity anomaly by incorporating abundant geophysical evidences, such as the International Ocean Drilling Program expedition 349, the interpretation of 10 seismic profiles and the bathymetric data in the Southwest Sub‐basin (SWSB) of the South China Sea. By inverting the crustal thickness by the application of the isostatic flexure analysis, comparing with ocean bottom seismic tomography result, then determining a detail crustal thickness of the study region, we calculated the RMA of the oceanic basin in the SWSB. The main features of the RMA and their relation to the palaeo‐spreading pattern are discussed, and the implications of the asymmetric lithospheric deformation due to variations in melt extraction are proposed. In the light of the asymmetric RMA at the north and south sides of the fossil spreading centre in the SWSB, we preferred asymmetric melt retention depth and extraction rate changes during the oceanic lithosphere creation of the South China Sea. Copyright © 2016 John Wiley & Sons, Ltd.