Abstract: Erlian rift system consists of more than50fault-depressions, major source layer is in Bayanhua group of Lower Cretaceous.Subjected to same regional tectonic event, fault-depression group has similar structure evolution history, also independent sedimentary unit distinguished from each other.Post-rifting regional uplift resulted in low maturity of source rock, wide difference from each other.Comparison of regional geothermal fields, analysis of organic geochemistry exhibi ted thermal evolution characteristics of organic matter in each fault-depression, established hydrocarbon-generation model, summarized the extent of oil formation zone, hydrocarbon-generation potential of source rock in three different fault-depression of Erlian rift system.Furthermore, it is pointed out that Ⅰ -type fault-depression enriched in oil is the most favourable target for oil/gas exploration.

Key words: Erlian basin, Rift belt, Early Cretaceous, Hydrocarbon evolution, Organic matter, Oil and gas origin