SANDBOX MODELING TEST FOR MESOZOIC BASINS IN SOUTHERN EAST CHINA SEA SHELF BASIN

The East China Sea Shelf Basin lies in the juncture of the Eurasian plate, the Pacific Plate and the Philippine Sea Plate, as a critical area in study of the global tectonic regime transformation event. Sandbox modeling is adopted in this paper to simulate the Mesozoic basin-mountain coupling and the evolution of the southern East China Sea Shelf Basin, which includes the Oujiang Sag, Yandang Low Uplift, Minjiang Sag, Taipei Low Uplift and Jilong Sag. It is found that the Mesozoic basin-forming process and the attributes of the East China Sea Shelf Basin are closely related to the subduction of the Izanagi Plate and the kinematics properties of the Offshore Fault associated with the subduction. It means, the tectonic evolution and basin-forming process of the Oujiang Sag, as a transpressional basin, is controlled by the kinematics property of the Offshore Fault. Away from the Offshore Fault, the Minjiang Sag and Jilong Sag, as extensional basins, are triggered by the retreat of subduction of the Pacific Plate. In Late Jurassic, according to the modeling data, the Offshore Fault was activated as a dextral transpressive fault, and the basin as a whole was a transpressive pull-apart basin associated with the subduction of the Pacific Plate. In the Late Jurassic-Early Cretaceous, the Offshore Fault switched into a sinistral strike-slip fault, inducing NW—SE-directed extension. Coevally, the properties of the Oujiang Sag, Minjiang Sag and Jilong Sag began their differential evolution. In the Early to Late Cretaceous, the Offshore Fault transformed into a dextral transpressional fault and in the Oujiang Sag there formed three sub-sags in left-stepping and en echelon pattern in geometry, which overlapped two proto-sub-sags in right stepping and en echelon pattern. Then the fault-controlled Yandang Low Uplift was formed, and separated by a NW—SE-striking fault, resulting in an en echelon and discrete geometry.