Multiple Linkage Patterns of Border Faults and the Main Controlling Factors in the Zhu I Depression of the Pearl River Mouth Basin, South China Sea

The Pearl River Mouth Basin (PRMB) is a significant offshore petroleum basin located in the northern South China Sea, characterized by its complex structural features and well-developed boundary faults. Despite its importance, several critical questions regarding fault growth, evolution models, and genesis mechanisms remain unresolved. This study aims to address these gaps by discussing the evolution of the boundary fault system and its associated stratigraphic record. This study utilizes high-resolution 3D seismic reflection data interpretation and fault displacement profiles to investigate the Zhu I depression, the largest hydrocarbon-bearing depression in the northern rifted zone of the PRMB. The findings indicate that the syn-rift growth of boundary faults within the Zhu I depression exhibits three distinct patterns, along-strike linkage, transverse linkage, and oblique linkage, which are formed under the action of the pre-existing basement fault systems. These patterns describe how individual fault segments connect and evolve during the rifting process, influencing the overall structural development of the basin and hydrocarbon accumulation. Although transverse linkage includes three development stages, consistent with previous studies, these stages are isolated normal faults, overlapping faults, and hard linkage. The study reveals a unique example of how transfer faults within a relay ramp connect the normal boundary faults on both sides. The break progression of the relay ramp can also be classified into three stages, similar to the transverse linkage. This study proposes a new approach, through the inversion of fault evolution by sequence migration, for the reconstruction of fault connection processes and complex fault linkage models developed in southern China and similar areas worldwide.