Cenozoic Tectonic Characteristics and Evolution of Liaodong Bay Depression

The Liaodong Bay Depression, located in the northeast of the Bohai sea, is an important oil and gas zone within the Cenozoic Bohai Bay Basin. The Bohai Bay is a basin characterized by complex structures, resulted from superimposition of multiple stages of tectonic evolution and dynamic processes. Based on 3-D seismic data, apatite fission track, and balanced cross-section analysis, structural development and tectonic evolution of fracture systems, tectonic styles and basin structures are studied in this paper. It is revealed that the NNE-trending fault system, which includes seven 1st order faults in the Liaodong Bay Depression, controls the formation of uplifts and sags on large scale. The Tanlu fault zone has three branches extending into the Liaodong Bay Depression i.e. the Liaoxi strike slip fault zone, the Liaozhong 1 fault and the Liaodong 1 fault. There are three uplifts and four sags developed in the Liaodong Bay Depression. The western uplift is continuously extended. It formed in early stage and was strongly uplifted while the eastern uplift is not continuous. Its southern part uplifted earlier and strong, while the northern part formed later and has obvious differences.