Basin‐Forming Mechanism, Basin Geodynamic and Hydrocarbon Exploration of the South Yellow Sea Rift Basin, East Asia: New Insights From Tectono‐Thermal Evolution and Geophysical Data

ABSTRACT The South Yellow Sea Rift basin (SYSB), located in the lower Yangtze Block, has distinct geological characteristics: a low thermal regime, thick lithosphere (~100 km), and no commercial oil fields. Here, we propose a comprehensive basin analysis that combines numerical simulations of tectonic–thermal evolution with interpretations of geophysical data to elucidate the origins of the low thermal regime, geodynamic background and hydrocarbon exploration potential in the SYSB. In this study, a geodynamic model and vitrinite reflectance‐depth profiles are used for basin modelling to determine the rifting stage, tectonic subsidence, stretching factor and heat flow evolution; seismic interpretation data are used to observe fault evolution, crustal detachment depth, tectonic inversion and trap formation; and deep reflection seismic profiles are used to observe crustal deformation and Moho surface morphology. The tectonic–thermal evolution history of the SYSB shows that the average maximum lithospheric extension factor is ~1.3, the tectonic subsidence is 1900–2200 m, and the average heat flow gradually increased to 76 mW/m 2 during the syn‐rift phase, which gradually decreased to approximately 66 mW/m 2 during the post‐rift phase. Compared with the petroliferous rift basins in eastern China, the SYSB has the lowest degree of tectonic subsidence, the lowest peak heat flow, and the lowest present geothermal field. Simple shear deformation controlled by crustal‐scale detachment faults dominated the continental lithosphere extension of the Lower Yangtze Block, and the evolution of the fault system suggests that these crustal‐scale detachment faults may have been formed by the reactivation of pre‐existing faults. The flat Moho morphology, continuous low thermal regime, and continental lithospheric extension dominated by simple shear of the crust imply that after the significant thinning of the Lower Yangtze Block in the Early Cretaceous, large‐scale thermal upwelling of the asthenosphere and pure shear deformation of the lithospheric mantle did not occur beneath the Lower Yangtze Block in the Late Cretaceous–Cenozoic. The hydrocarbon generation history suggests that the thermal evolution of the source rocks ended in the Oligocene tectonic inversion, and seismic interpretation reveals that the drilled traps were driven by the Oligocene tectonic inversion, indicating that these traps have no hydrocarbon accumulation potential. Future hydrocarbon exploration should focus on palaeogeothermal and palaeoburial methods to find mature hydrocarbon kitchens and evaluate the effectiveness of traps.