Major Unconformities and Sedimentary System Evolution in Pearl River Mouth Basin

Key words: 
• Pearl River Mouth Basin /
• unconformity /
• sedimentary system evolution /
• the shelf-margin delta

Abstract: Combined with the South China Sea spreading history, based on regional 2D seismic and drilling data, the paper focuses on the research of major unconformities, evolution of the Pearl River Mouth Basin and its controlling effect on the evolution of the Pearl River sedimentary system, aiming to provide support for the deep-water hydrocarbon exploration in the basin. Results show that:besides the basement, three major unconformity surfaces are recognized in the basin, i.e. breakup unconformity,slope-migrating unconformity and slope-gradient-jumped unconformity; according to the above three unconformities, the evolution of the Pearl River sedimentary system can be divided into four stages:rifting stage mainly develops depositional system of fluvial, lacustrine; fault-slope stage mainly develops shelf-margin delta(steep foreset);gentle-slope depression stage also develops shelf-margin delta (gentle foreset); steep-slope depression stage mainly develops delta-submarine canyon-submarine fan; the exploration of shelf-margin delta developed in faulted-slope stage and gentle-slope depression stage should focus along the shelf break; the exploration for delta-submarine canyon-submarine fan in steep-slope depression stage should adopt vertical exploration ideas, that is, searching for oil and gas perpendicular to the strike of the shelf break.