Tectono-Geothermal Coupling Effects on Paleogeomorphology and Source-to-Sink System Evolution of Steep Slope Zones in Lufeng Sag, Pearl River Mouth Basin, South China Sea

As a significant hydrocarbon-bearing sag in the Zhu I Depression of the Pearl River Mouth Basin, the Lufeng sag has long encountered exploration challenges owing to the dearth of comprehensive investigations on the source-to-sink system of the steep slope zone. To tackle this issue, this research utilizes paleogeomorphic reconstruction techniques to conduct a quantitative source-to-sink analysis and establish a hydrocarbon accumulation pattern in the steep slope zone of ductile deformation zones. The findings indicate that the longitudinal drainage systems developed during the intense rifting stage determine the proximal sedimentation. During the minor rifting stage, the area of the lacustrine basin contracted, and the pre-existing drainage systems converged into axial drainage systems. By the late rifting stage, the extent of the drainage system expands significantly, displaying distal sediment source characteristics. The tectono-geothermal regime governs the spatial scale of the source-to-sink system. Quantitative analysis reveals that the denudation and depositional areas in the ductile deformation zones notably exceed those in the brittle deformation zones, thereby creating favorable conditions for the large-scale development of sand bodies and hydrocarbon accumulation in the steep slope zone. These insights offer crucial guidance for future exploration in the steep slope zones of the fault basin.