Moho depth of the South China Sea basin from three-dimensional gravity inversion with constraint points

We calculate the gravity anomalies due to lateral changes in bathymetry from an independent topography compilation and those due to changes in sediment thickness and density. To estimate the Moho depth and the crustal thickness of the South China Sea basin, the 3D gravity inversion method is employed, which is based on the "initial model of fluctuated interface" from the constraint points from seismic data and sonobuoys. And then, the gravity data is corrected by the lithosphere thermal gravity anomalies within the continental margin of thinned lithosphere. Over most of the South China Sea basin, the Moho depth ranges 8 similar to 14 km, the crustal thickness is 3 similar to 9 km. The NNE trending fossil spreading center of the East and the Southwest subbasins extend to 112 degrees E, the Moho depth is more than 12 km, and the crustal thickness is over 6 km in the spreading center. However, the crust of the spreading center at the northwest basin is not obviously thickened. In the northern margin of the southwest basin, south of Zhongsha block, there is a crustal thinning belt, nearly EW trending, where crustal thickness is about 9 similar to 10 km. The 14 km isoline of the Moho depth and the 9 km isoline of the crustal thickness are very close to the continent-ocean boundary (COB), respectively.