Differential faulting in a narrow rift basin influenced by synchronous strike-slip motion: The Liaodong Bay sub-basin, offshore Bohai Bay Basin, China

摘要

Throughout the synrift stage of the Liaodong Bay sub-basin, offshore the Bohai Bay Basin in China, strike-slip motion within the Tan-Lu Fault Zone (TLFZ) greatly affected the local structural evolution. This led to abundant strike-slip, extension, and transtensional structural deformations within the Liaodong Bay sub-basin. The role played by the TLFZ in the evolution of the Bohai Bay Basin, however, remains unclear. This study evaluates the geometry and kinematics of faults and related structural styles within the Liaodong Bay sub-basin. Results reveal that very different structural deformations occurred across this long and narrow rift sub-basin, and show a shift of fault activity over time from west to east, and from extension to strike-slip. These differences in structural deformation across the basin indicate that strike-slip movement along the TLFZ mainly played a secondary role within the eastern part of the sub-basin, and was not responsible for the opening of the whole basin. Furthermore, it also indicates that the extensional and strike-slip dominated deformations within this sub-basin were driven by different geodynamics. The driving mechanism for strike-slip reactivation of the Cenozoic TLFZ is the subduction of the Pacific Plate beneath the eastern margin of the Asia continent. Differential faulting has also exerted an obvious influence on basin filling and hydrocarbon accumulation of the Liaodong Bay sub-basin.