The Cenozoic structure of the Zhu 3 Depression in the Pearl River Mouth Basin and its response to the dynamic background of the South China Sea

The Zhu 3 Depression is located at the transition between the South China Sea (SCS) and the South China Block. The Cenozoic structure reflects the dynamic background of the SCS. In this paper, 3D seismic data and log data are used to study the structural evolution of the Zhu 3 Depression. Based on fault activity and the distribution of stratum thickness, the Cenozoic rift deformation characteristics and the migration of the depocenter are defined. Spatial and temporal differences in the Cenozoic structure of the Zhu 3 Depression are due to the influence of pre-existing faults and regional stresses. The results show that there are three populations of faults with NE-, EW- and NW-striking in the Zhu 3 Depression. The NE-striking faults are mainly large-scale boundary faults. The W-E-striking faults are small and are activated in the late stages. The NW-striking faults are continuous at depth but are en-echelon and parallel to each other at shallow depth. On the basis of the above, we found that the NE- and NW-striking pre-existing faults divide the Zhu 3 Depression into different structural zones and control differences in deformation in the basin. Controlled by regional plate interactions and the Red River Fault Zone, the regional stress direction changes clockwise from NW-trending during the Paleocene to the NE-trending during the middle Miocene. These findings are expected to contribute to a better understanding of the evolution of the entire South China Sea. Thematic collection: This article is part of the Emerging knowledge on the tectonics of the South China Sea collection available at: https://www.lyellcollection.org/topic/collections/south-china-sea