RELATION OF YANSHANIAN EXTRUSION TECTONICS TO THE FORMATION OF THE BOHAI BAY BASIN: NUMERICAL SIMULATION BASED ON FLAC^2D

The formation and evolution of the Meso-Cenozoic Bohai Bay Basin is closely related with the Paleo-Asian Ocean Tectonic Domain, the Pacific Tectonic Domain and the Tethys Tectonics Domain. Previous structural analysis revealed that extrusion tectonics is one of the significant regimes to the formation of the Bohai Bay Basin. However, its geodynamics is difficult to be separated from the dynamics of plate boundaries. Therefore, this paper focused on their relation between its geodynamics and the regional stress fields by simulation based on FLAC^2D. The calculated result indicates that the northeast part of the Jiaoliao Block escaped northeastward and the southwest part eastward during Mesozoic while the Bolu Block escaped southwestward, and all these processes contribute to the last configuration of the Bohai Bay Basin. The results also reveal that the Pacific Tectonic Domain plays the most important role for the basin. Simultaneously, the North China Craton rotated anticlockwise with the variation in regional stress fields during different structural evolutionary stages. This result is in accordance with the Yanshanian tectonic outline of the study area.