The Yanshanian structural style and basin prototypes of the mesozoic Bohai Bay Basin
ZHOU Li-hong~3,LI San-zhong~2,LIU Jian-zhong~1,GAO Zhen-ping~3(1.Dagang Oilfield Company, CNPC, Tianjin 300280, China;2.Department of Marine Geology, Ocean University of China, Qingdao 266003, China;3.National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China)
Combined with seismic prospecting and interpretation of the deep layer in the Bohai Bay Basin in recent several years, this paper describes that the Yanshanian structural features and basin prototypes of Mesozoic Bohai Bay Basin and proposes that the Yanshanian structure can be divided into three levels of the upper, the meddile and the lower in the vertical and into three belts of the westward imbricated-thrust-fold belt in the west, the thrust\|strike-slip-fault belt in the medium and the thickened fold-reverse-fault belt in the rear or east. These structures resulted from folding and thrusting of the same NW-SE shortenings during two stages. The Mesozoic tectonics is divided into three stages of the early Yanshanian, the medium Yanshanian and the later Yanshanian. However, the features of folding and thrusting and basin prototypes changed with the different spatial and temporal variation. Especially the structural difference derived from the structural difference of the crystalline basement and the different superposition of different satges of structures. Other evidences show that the Yanshanian tectonic setting under the Neozoic Bohai Bay Basin formed in the compressive setting of the western Pacific continental marginal arc and in the delamination of the sub-crustal lithosphereas well as the intra-crustal escape.