南海北部珠江口盆地西南段断裂特征与成因讨论

珠江口盆地是南海北部陆缘新生代发育的裂陷型盆地,其油气资源丰富,且地处洋陆过渡带,盆地内部断裂特征复杂.在前人研究基础上,利用高分辨率三维地震数据,结合多属性分析技术,完善了区域断裂的精细化解释.将断裂构造类型依据断裂级别与规模划分为控盆一级断裂、控凹二级断裂、控带三级断裂、控圈四级断裂和控层五级小断裂;在盆地西南段发...

Characteristics and Genesis of Faults in Southwestern Pearl River Mouth Basin,Northern South China Sea

The Pearl River Mouth basin is a rift basin developed in the Cenozoic on the continental margin of the northern South China Sea, which is located in the ocean-continent transition zone with rich oil and gas resources. It is very important to analyze the internal fracture characteristics of the Pearl River Mouth basin. Based on previous studies, this paper uses three-dimensional high-resolution seismic data, combined with the application of coherent attribute analysis technology to refine the interpretation of regional faults. The faults are classified into the first-level basin-controlling faults, the second-level sag-controlling faults, the third-level belt-controlling faults, and the fourth-level ring-controlling faults in the area based on the level and scale of the faults. Single-section fault styles such as normal faults, form step-shaped, "Y"-shaped and other fault combinations on the seismic section. Among them, negative flower-like structures present in the Wenchang A sag in the Zhusan sag and unique core-shaped faults are widely distributed in the Kaiping depression of the Zhuer sag. During the Late Oligocene-Early Miocene, the fault direction rotated clockwise from NE→EW→NWW under the continuous right-handed stress field since the Cenozoic, and the activity intensity gradually weakened. It is also believed that affected by the collision of the India-Eurasia Plate, the subduction and retreat of the Pacific Plate and the continuous southward movement of the Paleo-South China Sea, the basin formed a typical extensional tensile stress field environment, which contributed to the development of three fault groups in NE-NEE and EW direction during the Eocene-Oligocene, and in the NWW-NW direction in Miocene. Moreover, the evolution and genetic mechanism of the fault structure in the southwestern part of the Pearl River Mouth basin are in good agreement with the changes in the stress field at the northern margin of the South China Sea.