Abstract:

Controlled by the expansion mechanism with nearly north-south direction，basins or depressions in South China Sea are mostly NE-SW extending, with three in the north and the other three in the south. The depressions parallel each other, and the ones in the center are wider than the ones around the margins.There are three basin types(pull-apart type, strike-slip type and extrusion type) that are divided into ten sub-types; In Cenozoic, there are four important regional tectonic movements that are diachroneity certainly, and develop three disrupt unconformities(between Early Oligocene and Late Oligocene, between Paleocene and Neogene, between Middle Miocene and Late Miocene), the era of disrupt unconformity is new gradually from east to west. Effected by the tectonic movement and sea-level change, the South China Sea develops three types of source rocks that are the lacustrine facies, the transitional facies and the terrigenous marine facies. From the north and south sides to the central basin, the source rock type gradually transit from the lacustrine and transitional facies to the terrigenous marine facies. From east to west, the layer of main source rock is gradually new(from Eocene and Oligocene to Oligocene and Miocene). The source rocks distribution is closely related to the disrupt unconformities, the earlier of the disrupt unconformity(between Early Oligocene and Late Oligocene),the main resource rocks form earlier(Eocene lacustrine facies source rocks) in basin. Otherwise, the later of the disrupt unconformity(between Middle Miocene and Late Miocene),the main resource rocks form later(Oligocene and Miocene transitional facies and terrigenous marine facies source rocks) in basin.

Key words: tectonic stages, basin type, disrupt unconformity, source rock, petroleum gas, South China Sea