The South China Sea is unique among the marginal seas of the Western Pacific. The study of the geological and structural characteristics of this basin are important for understanding the movements of the Eurasian, Indochina, and Pacific plates and the history of interaction between them. The modern passive continental margin in the northern South China Sea has been developed by the overlapping of the massive basement structures of Mesozoic age with rifting valleys of late Mesozoic to early Cenozoic age. Superimposed over these older structures are younger structures related to the mid-Cenozoic sea floor spreading of this region. Since this basin underwent short-term spreading, many of the older structural features in this region are well preserved. In this sense, the Sout China Sea is different from typical passive continental margins in terms of structural framework, geothermal history, sedimentation, and other geologic characteristics. Because of these differences, the northern South China Sea Basin is called a para-passive continental margin. The unique history of this basin, in combination with fluvial sedimentation systems from the Chinese continent, has formed multilayer and multitype conditions favorable for generation and accumulation of hydrocarbons (e.g., Pearl River Mouth). The exploration results obtained in the past ten years have led to discoveries of three large oil and gas fields, some medium and small oil and gas fields, and many petroliferous structures. These discoveries prove that this offshore area has great hydrocarbon pote tial.

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