Structural and Sedimentary characteristics of Meso-Cenozoic Basins in the Southern Lower Yangtze Region and Their Geological Implications

Tectonically, the southern Lower Yangtze region lies between the Dabie Orogenic Belt and Jiangnan Orogenic Belt. A series of Meso-Cenozoic basins developed in this area serve as a crucial window for revealing the basin structure and tectonic-sedimentary evolution in Eastern China. While geologically significant, the current understanding of these basins’ fundamental geological characteristics remains constrained. In particular, the basin’s structural framework and formation-evolution processes lack constraints from integrated geophysical data. This study conducted a systematic investigation into the structural characteristics, sedimentary filling patterns, and formation-evolution processes of three representative Meso-Cenozoic basins in the southern Yangtze region using deep seismic reflection and magnetotelluric sounding methods. The results indicate that two sets of thrust faults with opposite dips have developed within the crust of the study area, with the convergence center of the opposing thrusts located in the Huaining Basin, which controls the distribution of regional Jurassic strata. The central Huaining volcanic basin is associated with magma upwelling, with its main sedimentary filling occurring in the Early Cretaceous. In contrast, the Qianshan and Wangjiang basins are half-graben faulted basins formed under extensional stress. These faulted basins entered an active phase since the Late Cretaceous, marked by discontinuous sedimentation of the Upper Cretaceous to Paleogene strata. The boundary fault of the Qianshan Basin is considered the eastern branch fault of the Tan-Lu Fault, characterized by an evolutionary history of early strike-slipping followed by late-stage extension. Moreover, the boundary fault of the Wangjiang Basin exhibits a negative inversion structure, undergoing a dynamic transition from an early compressional thrusting phase to a subsequent extensional regime. The southern Lower Yangtze region experienced at least two compressional tectonic events during the Paleogene, which induced differential uplift and erosion of the basins. In light of the above analysis, a structural and sedimentary evolution model for the Meso-Cenozoic basins in the southern Lower Yangtze region has been constructed. The research findings provide important support for regional oil and gas exploration practices and further deepening the understanding of tectonic evolution processes in the Lower Yangtze region.