Abstract:

Southern Yellow Sea is the main body of Lower Yangtze plate. From shallowly buried continental strata to deeply buried marine strata, a breakthrough in oil and gas exploration can not be still obtained through many years work，and the exploration and understanding level are low. Fully combining with the achievements and understanding in the continental area of Lower Yangze plate and being based on seismic and drilling data in the Southern Yellow Sea, the Longtan Formation, the Dalong Formation of Permian period and the Qinglong Formation of Triassic period are divided into six sedimentary systems in the Southern Yellow Sea, which are fluvial, delta, tidal flat, open platform, limited platform and shelf, whose features of each sedimentary system were analysed. On the basis of seismic reflection characteristics, four types of seismic facies were recognized and the sedimentologic meaning of each seismic facies was studied. Combining with wells sedimentary facies and seismic facies, the sedimentary systems distribution characteristics were sculptured. Longtan Formation, Dalong Formation and Qinglong Formation share the similar sedimentary environment characteristics that the northwestern area has a deeper water depth than the southeastern area. Study area experienced twice larger-scale transgression to regression cycles, which formed the base-level oscillating texture in stratigraphic records. With the base-level changes, typical sedimentary evolution sequence formed, which is that tidal clastic rocks and coal bed combination changes to shelf shale, and up to open and restricted carbonation flatform combination from the bottom up.

Key words: Lower Yangtze plate, the Southern Yellow Sea, sedimentary system, seismic facies, sedimentary evolution