Formation and evolution of the Chinese marine basins

There are plenty of petroleum resources in the Chinese marine basins, which will be the potential exploration regions of petroleum in the 21st century. The formation and evolution of the Chinese marine basins have mainly undergone two major tectonic epochs and five tectonic evolution stages. The first major tectonic epoch is the early Paleozoic plate divergence and drifting epoch during which the marine basins were formed, and the second one is the late Paleozoic plate convergence and collision epoch during which the pre-existent marine basins were superimposed and modified. The five tectonic evolution stages include: (1) the drifting of micro-continental plates in Oceans and the formation of marine basins mainly filled with carbonate rocks during Proterozoic-Middle Carboniferous; (2) the northward collage and convergence of continental plates and the development of the paralic sedimentary basins during Late Carbon iferous-M idd le Triassic; (3) the tectonically stabilized stage after the plate collage and the superimposition of lacustrine basins controlled by the inland subsidence during Late Triassic-Early Cretaceous; (4) the stage of the inland deformation and successive deep burial, uplifting, erosion or breakage of marine basins influenced by the plate tectonic activities of Neo-Tethys Ocean and the West Pacific developed in Late Cretaceous-Paleocene; (5) the stage of the foreland compression and basin-range coupling in the margin of the marine basins caused by the collision between India and Eurasia Plates and its long-distance effect since Neocene. The process of the tectonic evolution has controlled the petroleum geologic characteristics of Chinese marine basins, and a material foundation for the formation of oil and gas reservoirs has been built up via the formation of Paleozoic marine basins, and the Mesozoic-Cenozoic tectonic superimposition and modification have controlled the key conditions of hydrocarbon accumulation and preservation. From the Late Proterozoic to the Early Paleozoic, the stratigraphic sequences of the deep-water shale and continental margin marine carbonate rocks in the ancient plate floating in the oceans have developed high-quality marine source rocks and reef-shoal reservoirs. In Late Paleozoic, the crustal plates converged and uplifted into continent and the paleouplifts in the intra-cratonic basins have become good reservoirs of hydrocarbon migration and accumulation, and paralic coal beds have formed regional cap rocks. The Mesozoic-Cenozoic tectonic stability has determined the preservation condition of the Paleozoic marine basins. The marine basins have Precambrian crystal basement, the tectonic activities are relatively stable and the basin modification is relatively faint, and the ancient reservoirs are fit for preservation, such as the Tarim Basin, Sichuan Basin and Ordos Basin. They are all potential regions for marine oil and gas to be explored.