Discussion on the spatial and temporal difference of Cenozoic rift formation and evolution and its genesis mechanism in the Pearl River Estuary Basin

To deepen the understanding of the temporal and spatial differences. In the this study is based on the seismic profile data of the the Pearl River Mouth Basin, using the methods of structural analysis, balanced profilerestoration and fault activity rate calculation, the fault system and structural evolution process of the the Pearl River Mouth Basin are analyzed. Moreover, the. causes of structural differences in the depressions in this Basin are explored in combination with the pre-existing structure, basement characteristics and dynamic background of the basin. The main results are as follows: The basement pre-existing structures in the Pearl River Mouth Basin mainly developed a series of NE trending thrust faults and the conjugate NW trending pre-existing thrust fault system; The faults in the Pearl River Mouth Basin show NE, NEE, near EW and NWW strike from west to east, controlling the tectonic framework of the basin during the rifting period; The evolution stages of the basin are divided into four stages: the early stage of rift (E1sh-E2w), the development stage of rift (E3e), the depression stage (E3z-N1z-N1h), and the tectonic activation stage (N1y-N2w-Q); The fault system in the basin mainly exhibits a clockwise transition from NE-NEE extensional properties to nearly EW-NW extensional strike slip properties. This is due to the long-term inheritance and development of some main faults along the basement pre-existing faults during the rift period. At the same time, the differences in basement pre-existing structures and lithology result in different tensile and shear strengths, as well as being controlled by peripheral plate movement, magmatism, and regional stress field changes. The rift structure of the basin has undergone a transformation from north to south, from narrow and narrow grabens and semi grabens with "thick below and thin above" characteristics to wide and gentle grabens and semi grabens with "thick above and thin below" characteristics. The distribution of sedimentary centers in the basin shows a migration pattern along the NE direction.