Mesozoic-paleozoic Tectonic Evolution In The South Yellow Sea Basin And The Comparative Analysis With Sichuan Basin

The South Yellow Sea basin locates in the Lower Yangtze region, and has a wide range of Mesozoic-Paleozoic marine strata with large thickness. The Mesozoic-Paleozoic marine strata in South Yellow Sea basin is the focus of this thesis. According the collected seismic profiles and drilling data, coupled with the formation and drilling data of the northern Jiangsu area, the thesis summarized the development and distribution of Mesozoic-Paleozoic marine strata in the South Yellow Sea Basin and divided the marine strata into up marine structural layer and down marine structural layer.Summarizes According to the Basin Seismic Profiles, the thesis summarized the fracture characteristics of the South Yellow Sea and different tectonic style in different tectonic movement under the fracture characteristics of the formation,such as the of the South Yellow Sea Basin extensional tectonic style, extrusion tectonic style and the style of inversion structures and inversion style. Based on all the Geophysical data, the thesis made a detailed exposition of the total tectonic evolution of the South Yellow Sea Basin, and there are8periods in marine sedimentary period before Indo movement and terrestrial sedimentary period after Indo movement and7different prototype basin evolution stages:Z2—O、S—D、C—T2、T3—J1-2、J3—K1、K2—E、N—Q, and the basin has experienced a steady deposition to gradually collage, oscillating migration, pleated squeeze off collision orogeny pressure conversion and strike-slip subsidence, extensional fault block. The south sea basin in Paleozoic is primarily the stable platform deposition stage, which experienced early foreland, post-extrusion, pull-apart period and rift, depression basin period in Late Mesozoic and Cenozoic. In this thesis, the tectonic background and strata features in various evolutionary phases were analyzed and summarized.The thesis take the south yellow sea basin and Sichuan basin as example,which locates in upper Yangtze region. The marine strata and tectonic evolution of the two regions were compared and the source rock, reservoir, seal and other conditions of hydrocarbon accumulation are described and compared in the two regions. Based on this,1draw a conclusion that the largest difference is the influence of the Pacific tectonic domain since the Mesozoic,the south yellow sea in the east got a huge transformation and serious destruction of marine strata, resulting in the destruction of the oil and gas reservoir storage conditions, while the Sichuan basin in the west has more complete Mesozoic and Cenozoic strata with a better reservoir storage condition. In comparison, the evolution of the Paleozoic marine deposits in the two regions is much the same, developing the similar s reservoir storage condition. According to the comparison with Sichuan basin,which have had breakthrough in oil and gas exploration, coupled with the tectonic evolution and accumulation conditions in south yellow sea, the thesis analyzed and forecasted the next oil and gas exploration prospects and the possible combination of accumulation mode, which provide the basis for the next South Yellow Sea region oil and gas prospect evaluation, follow-up exploration t and the geological development in south yellow sea and make China’s future energy development has an important practical value.