Tectono-sedimentary evolution of the Mesozoic in the southern East China Sea Shelf Basin and its bearing on petroleum exploration

The East China Sea Shelf Basin is located on the southeastern margin of the Eurasian Plate. Since Mesozoic, the formation and evolution of the basin are characterized by multiphase oceanic subduction of the Paleo-Pacific plate and superimposition of multistage tectonic systems. As the results, many questions, such as prototype of the basin, tectono-sedimentary evolution and hydrocarbon accumulation, have always remained in puzzle. Based on the latest seismic surveys and the drilling data from adjacent land areas, this paper is devoted to the key problems and exploration directions of the Mesozoic hydrocarbon accumulations, through sea-land correlation, establishment of Mesozoic sequence stratigraphy and remodeling of tectono-sedimentary evolution process. It is found that there are two super-sequences and seven seismic sequences in the Mesozoic in the basin. It was a passive continental margin before Late Triassic, an active continental margin depression in Late Triassic-Middle Jurassic, but a faulted basin on an active continental margin in Cretaceous. It is proposed that the basement of the basin in early stage was in NE direction which controls the framework of the Mesozoic basin and macroscopic hydrocarbon-bearing properties. Corresponding to the two-stages of tectonics, there are two sets of Mesozoic source-reservoir-caprock combinations. The Keelung movement, Yushan movement and Yandang movement dominated the formation and accumulation of early-stage oil and gas, while the Longjing movement contributed to the reform of oil and gas reservoirs. Inherited uplifts (slope), such as the Minjiang slope and the " uplifts in depressions” in the Taipei transitional zone, are the main petroleum exploration targets in the future to come.