TECTONIC EVOLUTION AND OIL AND GAS POTENTIAL IN NORTHERN TARIM BASIN

The northern Tarim Basin has undergone 6 evolutionary phases since the middle Proterozoic:1)The development of Xinjiang paleoplate (Pt₂-∈₁); 2)The formation of the passive continental margin (∈₂-O₁); 3)The subduction of the Tarim paleoplate to the Yining-Middle Tianshan paleoplate (O₂-C₁); 4)The colliding foreland depression period(C₂-P); 5)The depression period of colliding predmount(T-N₁); 6)The colliding reactivated predmount depression(N₂-Q). The northern Tarim Basin can be subdivded into 2 tectonic parts: i.e. the northern Tarim uplift belt and the Kuche-baicheng thrust fold belt. The former is a high basement uplift in which Paleozoic strata was erosed seriously, and ancient buried hills and anticlines were well developed. It is the most promising zone owing to its bordering on the Manjiaer and Ku-che oil generation depressions.The latter consists of a double-deck structure, the upper is characterized by a series of thrust faults and folds in the Meso-Cenozoic strata; the lower is made up of the Paleozoic strata. The sedimentary formation of the passive continental margin overridden by the south Tianshan nappe is important source rocks. Besides the oil-bearing Meso-Cenozoic strata, it is expected that there are a great amount of Paleozoic gas resources in this zone.