Abstract:

Gravity anomalies can be used to infer the deep crustal structure in the South China Sea (SCS) where seismic data are limited to some specific points or profiles. This paper presents a comprehensive study of crustal structure by using gravity inversion for interface with seismic data constraints to invert depth of the Moho and to calculate crustal thickness, and by performing gravity anomalies correlative imaging method without constraints to construct the 3D subsurface distribution of equivalent density in the South China Sea. We also focus on the regional linear features of gravity anomalies and jointly use the continuation, horizontal gradient and linear feature enhancement filter to highlight the linear tectonics which always involve the density changes in horizontal, such as major deep faults, boundary of continental oceanic crust, spreading axes of oceanic basin. The integrated geophysical analysis along the Guangzhou-Palawan geosciences transect demonstrates that the characteristics of the gravity anomalies and their inversion results allow us to reveal crustal structure and regional tectonics features in the large scale of the South China Sea.

Key words: South China Sea; gravity anomaly; crustal structure, regional tectonics