Meso−Cenozoic deformation and dynamic mechanism of the ocean−continent transitional zone in the East China Sea

Continent-ocean transition zone (COT) is a key to better understanding the geodynamic process and its mechanism between ocean and continent and has long been one of the hot issues in geoscientific research. The Southern East China Sea Shelf Basin (SECSSB), Zhejiang, Fujian and Guangdong regions, located at the eastern South China Block, have suffered from the westward subduction of the Izanagi Plate and the Pacific Plate as well as the far-field effect of the collision of the Indian Plate and the Eurasian Plate since Mesozoic, and complete records on tectonic deformation and COT interaction in this period are preserved. Based on geological and geophysical data acquired over the last 10 years, synthesizing Meso-Cenozoic research results and making land-ocean correlation, this paper studied the Meso-Cenozoic tectonic deformation and dynamic mechanism of the SECSSB and its adjacent areas. Based on the field geological survey, this paper provides a summary of the Meso-Cenozoic tectonic deformation in the land area. 4 major regional unconformities and 4 main structural layers are recognized, in addition to the 6 tectomagmatic periods and 5 large regional faults which have great influence on the Meso- Cenozoic sedimentary evolution. Meanwhile, this paper also summarized the Meso- Cenozoic stratigraphic framework and recognized 5 types of tectonic styles and 12 tectonic combinations in the SECSSB. Faults mainly trend in NE−NNE except a few small ones trending in EW. Magmatic rocks were mainly formed during the Yanshanian and Himalayan periods and display a spatially regular migration from west to east. Numerical simulation results show that slow-stretching model is consistent with the Mesozoic tectonic setting and local water-bearing mantle melting of the region since plate subduction is believed the main reason for the formation of magmatic rocks in the study area. Based on the study mentioned above, we discussed in details the Meso-Cenozoic tectonic evolution and basin type in this paper.