Geological structure of the large section in eastern China's sea areas and its constraint on comprehensive stratigraphic division

Based on the geophysical and geophysical data collected in recent years,the authors carried out the joint gravity- magnetic-seismic inversion in eastern China's sea areas and studied the characteristics of the basement and geological structure of each structural unit systematically. Constrained by the joint interpretation,the authors carried out the unified sea-land stratigraphic regionalization and predicted the favorable oil- bearing prospective areas of Mesozoic. The basement of the East China Sea shelf basin is composed of Proterozoic and Paleozoic strata,and 5 sets of tectonic layers are developed in the caprock. The south Yellow Sea basin having dual basement and caprock feature can be divided into 8 tectonic layers. The East China Sea shelf basin is dominated by the late Mesozoic Yanshanian transformation. The lower tectonic layer of the Yellow Sea basin is mainly characterized by extrusion deformation while the middle tectonic layer is mainly characterized by multiple structural styles formed by extension. The depth of the Moho surface is stable in the study area,which is usually about 30 km. The upper mantle is slightly elevated in the Wunansha-middle uplift. The Moho depth in the East China Sea shelf basin is generally deeper than that in the South Yellow Sea Basin—Sulu orogenic belt. Eastern China's sea areas and their adjacent areas can be divided into 2 first level stratigraphic regions (Eurasian),6 second level stratigraphic regions and 14 third level stratigraphic regions. The study of large cross- section stratigraphic structure reveals that the Mesozoic and Paleozoic strata are widely developed in south Yellow Sea and the East China Sea. The thick Meso-Paleozoic strata provide a rich material basis for oil and gas formation and accumulation.