The immature source rocks of oil in China's continental basins mainly formed in big lake basins influenced By transgression

small fault-subsided lake and gypsum lake basins. Corresponding source materials were algae

desMonollinite related to terrigenous plant

the soluble asphaltene and non-hydrocarbon organic matter preserved in gypSolyte environment. Bacterial action was favourable for organic matter to be inverted into immature oil

and thermal effect was an important condition for the formation of immature oil.