关键词: 南海, 珠江口盆地, 下第三系, 海平面变化, 深水扇系统, 层序地层学, 油气资源

Abstract: Plenty of well data and 2D seismic data obtained from the shallow-water shelf region were used to identify six tertiary sequences from 21million to 10.5 million years before present with the sequence stratigraphic analysis. The deep-water fans were figured out in corresponding lowstand system tracts. The deep-water fan of every sequence was overlapped in Baiyun Depression. Micropaleontologic quantitative analysis for 60 exploration wells demonstrated that there were six times of tertiary sea level change from 21 million to 10.5 million years before present, which is consistent with the regulation of global tertiary sea level change. Periodic sea level falling, abundant sediment supply from the Paleo-Pearl River and long-term thermal subsidence of Baiyun Depression in Pearl River Mouth Basin resulted in the slope deep-water environment, which is the key factor for development of deep-water fan system of the Pearl River in the South China Sea. The deep-water slope deposition system in the northern South China Sea is similar to the deep-water deposition systems in the Atlantic deep-water petroleum exploration hotspots. They are both located in the passive continental margin and own long-term thermal subsidence and abundant supply from large paleo-river. Recent discovery of a large natural gas field in the northern slope of Baiyun Depression demonstrates its great resource potential in the huge lacustrine source kitchen in the Eogene of Baiyun Depression. The multi-period deep-water fans vertically superposed on the source rock will become the key fields for petroleum exploration.

Key words: South China Sea, Pearl River Mouth Basin, Eogene, sea level change, deep-water fan system, sequence stratigraphy, petroleum resources