Complex Fault Systems and Basin Evolution of the Bonan Area, Eastern China: Effects on the Sedimentation and...

The Bonan area, characterized by complex fault systems and multistage tectonic evolution, represents a critical hydrocarbon exploration target in the southern Bohai Bay Basin. Understanding the fault systems, depositional systems, and source rock distributions is crucial to hydrocarbon prospecting in this area. Here, we present a comprehensive characterization of the Cenozoic fault systems using high-precision 3D contiguous seismic data for the Bonan area. Analysis reveals, for the first time, a "three groups, three types" fault system organization that fundamentally controls the spatial-temporal distribution of depositional systems and source rocks. Specifically, three directional fault groups (NNE, NE, and EW/NWW), three fault types based on kinematic properties (strike-slip, extensional, and strike-slip-extensional), and three distinct tectonic evolution stages are identified. It is demonstrated that the early Cenozoic depositional systems were governed by the coupled interaction of EW-trending basin-controlling faults and NNE-striking-slip faults. In contrast, late Cenozoic deposition was controlled by a unified basin subsidence. These findings provide a new conceptual framework for understanding fault-controlled hydrocarbon systems in complex rift basins and offer practical guidance for exploration targeting in the Bonan area and analogous basins worldwide.