关键词: 托克逊凹陷, 科牙依凹陷, 油气勘探前景, 前侏罗系, 吐-哈盆地

Abstract: It is obvious that there are no Upper Permian and Lower Triassic in the Toksum Depression and Keyayi Depression in the western Turpan-Hami Basin,and has an angular discordance between Middle Carboniferous,Lower Permian and Middle Triassic.In the period of Carboniferous and Early Permian, vocanic activity was strong with high geotemperature.During Middle Triassic,a extend lake appeared in Toksum and Keyayi areas.The hydrocarbon generating center was in Keyayi area in which the good source rocks were developed.The fan delta reserviors were developed in littoral-shallow lake in Toksum Depression,the oil derived from Middle Triassic is mainly come from Keyayi area.In the later Triassic,the depocenter had been migrated to middle and southern Toksum Depression where littoral-shallow lake facies were developed.The Indosinian movement and early Yanshanian movement are tectonic thermal events which play an important role in the maturity of source rock.The northern-western Toksum Depression has fairly good oil exploring prospect because it is near hydrocarbon generating center,and physical property of fan delta sandbodies has been improved in lately tectonic movements,and the period of hydrocarbon generating is close to that trap structures forming as well as it is situated in the place where fractures developed.Pre-Jurassic in Keyayi Depression has perfect formative conditions of oil-accumulation,but has poor conservative conditions.

Key words: Toksum Depression, Keyayi Depression, oil-gas exploring prospect, Turpan-Hami Basin