The formation and spatial distribution of sedimentary systems in rift-lake basins are jointly controlled by multiple factors, including sediment supply rates from source areas, clastic sediment transport pathways, and basin geometry and intrabasinal structural configuration (e.g., accommodation zones and faults), which strongly influence the architecture of depositional systems and basin filling processes. The Wenliu Formation (Wenliu Member, Late Paleogene) of the Wenchang Group in the Enping 20/21 Depression of the Yangjiang East Sag, Pearl River Mouth Basin, developed a multi-source and multi-channel sand-transport system; however, the matching relationships and coupling mechanisms among different source areas, transport pathways, and depositional systems remain poorly understood. Based on three-dimensional seismic data, drilling, and well-log information, combined with heavy mineral assemblages and detrital zircon U–Pb age spectra, this study comprehensively investigates the source areas, paleochannel clastic sediment transport pathways, and depositional systems of the Wenliu Member, systematically establishing the source-to-sink (S2S) framework. The results indicate that sediments of the Wenliu Member were supplied from four main source areas, including the northwestern Yangchun Uplift, northeastern Enyang low uplift, and southwestern Yangjiang low uplift, with nine major paleochannel clastic sediment transport pathways identified. The different source zones show distinct variations in area, slope characteristics, and sediment supply modes, corresponding to differentiated paleochannel types and paleodrainage configurations. The study area overall exhibits a typical multi-channel convergence depositional pattern, dominated by braid-delta and fan-delta systems. The Enyang low-slope source zone generated the largest braid-delta deposits, whereas fault-transformed source zones produced fan-delta deposits adjacent to active faults and along basin-margin fault systems. Quantitative analysis further indicates that depositional-system scale is significantly correlated with source-area size, paleodrainage development, and paleochannel geometric parameters. Large depositional bodies are more likely to form when the source area exceeds ~60 km2, the paleochannel width exceeds ~1.4 km, and the cross-sectional area exceeds ~10 km2. Integrating the spatial relationships among source areas, transport pathways, and depositional systems, four source-to-sink subsystems are identified, which can be further classified into two typical depositional patterns: a long-source gentle-slope braid-delta pattern and a proximal-source rapid-accumulation fan-delta pattern. This study elucidates the coupling relationships among source areas, clastic sediment transport pathways, and depositional sinks in a multi-source rift-lake basin, providing a geological basis for predicting sedimentary systems and guiding hydrocarbon exploration in the study area.
Zhang et al. (2026) studied this question.