The synsedimentary faults and basin-marginal fans located in the central part of the deep-water area of the early Oligocene Qiongdongnan Basin have been investigated using seismic profiles, boreholes, and well-log data. Through the formations of the characterized paleogeomorphology, such as transverse anticlines, fault ditches, and step-fault belts, the synsedimentary faults are known to have controlled the development position, distribution direction, and extension scales of the basin-marginal fans. For example, at the pitching ends of two adjacent faults, transverse anticlines developed, which controlled the development positions and distributions of the fans. During the early Oligocene, the faults controlled the subsidence center, and fault ditches were formed at the roots of the faults. In the surrounding salient or low salient areas, which were exposed as provenance areas during early Oligocene, the fault ditches acted as the source channels and determined the flow paths of the clastics, where incised valley fills were obviously developed. The fault ditches which developed in the sedimentary basins were able to capture the drainage systems and influenced the distributions of the fans. The large boundary faults and the secondary faults generated two fault terraces and formed step-fault belts. The first fault terrace caused the clastics to be unloaded. As a result, fans were formed at the entrance to the basin. Then, the second fault terrace caused the fans to move forward, with the fans developing in a larger extension scale. The results obtained in this study will potentially be beneficial in the future prospecting activities for reservoirs and coal-measure source rocks in the basins located in the deep-water areas of the South China Sea.

利用地震剖面，井眼和测井资料对位于渐新世琼东南盆地早期深水区中部的同沉积断层和盆地边缘扇进行了研究。通过特征性的古地貌结构，如横向背斜线，断层沟和阶跃断层带，同沉积断层已经控制了盆地边缘扇的发育位置，分布方向和扩展尺度。例如，在两个相邻断层的俯仰端，形成了横向背斜线，这些横向背斜线控制着扇形的发育位置和分布。在渐新世早期，断层控制了沉降中心，断层根部形成了断层沟。在周围的显着或低显着区域，早渐新世时期它们被暴露为物源区，断层沟渠作为水源通道并决定了碎屑岩的流动路径，在该碎屑岩中明显形成了切开的河谷填充物。沉积盆地中发育的断层沟渠能够捕获排水系统并影响风机的分布。大的边界断层和次生断层产生了两个断层阶地，形成了阶跃断层带。第一个断层带导致碎屑被卸载。结果，在水池入口处形成了风扇。然后，第二个断层带导致风扇向前移动，风扇以更大的扩展规模发展。