Cenozoic tectonic evolution of the East China Sea Shelf Basin and its coupling relationships with the Pacific Plate subduction

Abstract

The East China Sea Shelf Basin is one of the Mesozoic-Cenozoic basins located in the edge of eastern China continent whose formation and evolution are closely related to the subduction of the Pacific Plate. However, the underlying correlations between the tectonic evolution of the East China Sea Shelf Basin and the Pacific Plate subduction (65 Ma to present) remain poorly understood. In this paper, the basin is divided into western and eastern depression groups to further study its tectonic evolution. In combination with the characteristics of Pacific Plate subduction, this paper performs a coupling analysis of the basin evolution regarding its migration direction and evolution rate. The results of balanced section and deformation rate analyses reveal that the East China Sea Shelf Basin experienced different regional activities during the Cenozoic, which could be summarized as four geologic periods and three tectonic evolution stages. In this interpretation, it is recognized that tectonic activity occurred in the western depression group and then shifted to depocenters of the eastern group. In contrast, the Pacific Plate subducted westwards beneath the Eurasian Plate over the same geologic time span. Surprisingly, a slightly negative correlation between the intensity of the tectonic deformation of the East China Sea Shelf Basin and the subduction rate of the Pacific Plate is demonstrated when the subduction rate is no more than 75 mm/a. However, the basin deformation intensity increases with the plate subduction rate after 75 mm/a. The results of this work have implications for explaining the major role that the subduction of the Pacific Plate played in the formation and evolution of the eastern China basins.