关键词: 南海北部, 珠江口盆地, 白云凹陷, 珠海组, 三角洲沉积体系, 陆架坡折

Abstract: The drilling data, geophysical data in the north part of Baiyun Depression and ODP files were used to well-seismic analysis, strata correlation and seismic stratigraphic interpretation. The results showed that Baiyun Depression was in the continental shelf in the late Oligocene from 32.0 Ma to 23.8 Ma before present. The large-scale shallow-water continental delta sandstone and mudstone inter-bedding deposits of Zhuhai Formation were developed around Baiyun Depression, which is different from half-deep or deep water fine deposit since 23.8 Ma. At the same time, the upper surface (at 23.8Ma) and lower surface (at 32.0Ma) of Zhuhai Formation are two large unconformities created by two times of large-scale structural movement in the South China Sea and the transferring interfaces of sedimentary-tectonic-climate conditions. During deposition period of Zhuhai Formation, the continental-shelf slope break migrated from north to south till to the southern uplift belt in the Pearl River Mouth Basin, and the large progradational delta depositional systems was clesely correlative with the extensive regression of relative sea level changes in the late Oligocene. Zhuhai Formation in Baiyun Depression has good shallow marine delta reservoir-seal combination conditions, which is significant for petroleum exploration in deepwater area of Baiyun Depression.

Key words: north part of South China Sea, Pearl River Mouth Basin, Baiyun Depression, Zhuhai Formation, delta deposit system, continental shelf slope break