Abstract: The Taricuo deep depression located in the northern depression of Cuoqin basin is a tectonic-composite basin formed under a compressive background. There developed two petroleum systems--one key petroleum system and one petroleum subsystem. With respect to the petroleum subsystem,the hydrocarbon-generating threshold depth is 3000~4200 m, the temperature for hydrocarbon- generating window is 100~140℃, and the key moment of hydrocarbon generation in petroleum subsystem is 65 Ma ago. Owing to complicated tectonie movements, the Taricuo deep depression might lack preservation conditions necessary for forming large-scale oil-gas pools,Cenozoic formation,which is well-preserved, will be the favorable target for oil-gas exploration.

Key words: Tibet, Cuoqin basin, petroleum system, source rock, reservoir, cap rock