Mesozoic multistage deformation and mechanism of the Central Bohai Bay Basin formation

Revealing the structural characteristics of multistage deformations and evolution of the Central Bohai Bay Basin during the Indosinian and Yanshanian could provide theoretical support for oil and gas exploration of buried-hills. Based on a detailed structural analysis on the 3D seismic data in the study area, we determined the stratigraphic division, tectonic sequence, and superimposed modification of late deformation on early one, and analyzed the mechanism of the deformation in each stage. The Central Bohai Bay Basin developed three main groups of faults in the Mesozoic. The Indosinian Movement triggered northward thrusting, forming NW to nearly EW-trending imbricated thrust faults that underwent negative inversion during the Late Jurassic to Early Cretaceous. The NNE to nearly SN-trending tear faults formed during the Indosinian regulated the movement among different blocks. The Yanshanian Movement evidenced two episodes of NW-SE compression during the late Middle Jurassic and Late Cretaceous, respectively. The compression formed NE-SW-trending reverse faults of which some parts inherited Indosinian fault plane. In addition, the Indosinian tear faults evolved into transpressional sinistral strike-slip faults in the Yanshanian, constraining the scale of the NE-trending reverse faults.