摘要
The deepwater area of the northern South China Sea underwent multistage rifting in Paleogene and came into depression stage in Neogene.Lacustrine and transitional source rocks were formed mainly in the rifting period,while marine source rocks developed mainly in the depression stage.The transitional source rock is one of major source rocks in the deepwater area of the northern South China Sea.Oil and gas found in the northern South China Sea are mainly generated from transitional source rocks of Yacheng Formation and Enping Formation,while Zhuhai Formation marine source rock makes an important contribution to oil in the deepwater area of the Zhu II Depression.Natural gas in the Qiongdongnan deepwater area is a typical coal-type gas generated from Yacheng Formation humic source rock,but gas in the ZhuⅡ Depression of the Pearl River Mouth Basin is neither a typical coal-type gas nor an oil-type gas,instead it is a transitional gas generated from Enping Formation humic-sapropel source rock.