Depth distribution of Moho model and tectonic patterns in South China Sea and adjacent areas

Abstract

This study aims to investigate the depth distribution of Mohorovicic discontinuity (Moho) and its relationship with the tectonic pattern of the South China Sea and adjacent areas. To achieve this, the spatial characteristics of the full tensor gravity gradient data are analyzed to identify 17 large and deep faults and to divide the study area into 9 tectonic units with distinct geological structures. Using a three-dimensional (3D) interface inversion method, the Moho depth is determined, constrained by the Moho depth information obtained from sonar-buoy detection and submarine seismograph detection profiles. By analyzing the relationship between the distribution characteristics of Moho and tectonic units, the study summarizes the trend, relief, gradient of Moho, and crustal properties in the study area. Additionally, the seismically constrained Moho undulation combined with the gravity data, gravity gradient anomalies and unconstrained 3D correlation imaging are employed to study the crustal structure of the South China Sea, investigate the vertical and horizontal changes of the crustal structure, and reveal the large-scale crustal and regional structure of the South China Sea. Through the coupling analysis of shallow and deep structures, the study reveals that the gravity gradient anomalies and 3D correlation imaging are consistent with the variations of the Moho depth, indicating the presence of a trench-island arc-back arc basin system and the distribution of continental crust, oceanic crust, and transitional crust in the South China Sea.