The coastline of southeastern China is about 18,000 km (11,200 mi) in length, and its aggregate continental shelf area within 200-m (660-ft) water depth is well over 1 million km2 (390,000 mi2). Recent geophysical exploration and petroleum drilling records aid in understanding the geologic evolution of these petroliferous basins. Two types of tectonic basins are present on the continental shelf areas: (1) Bohai Gulf, South Yellow Sea, and Beibu Gulf are intraplate polyphase rift-depression basins, and (2) East China Sea, mouth of the Pearl River, and the Yingge Sea are epicontinental rift-depressions basins. Both types are believed to be of extensional origin. The severe convergence of the Indian plate with the Eurasia plate produced east-northeast-spreading of the South China Sea basin, which resulted in two triple junctions on its northern margins. The Pacific plate was subducted by downthrust beneath the Eurasia continental crust. The extension mechanism could be the rising of an upper mantle plume to produce two weak north-northeast-trending fracture zones. A series of intraplate and epicontinental riftdepression basins was formed.
The depositional models and sea level variations of these basins have been interpreted from drilling records and seismic profiles. They can be explained by the tectonoeustatic changes in sea level and Cenozoic climatic changes in China.