Abstract:

The typical thrust-fold nappe structural belt occurred in the south margin of Jiuxi Basin is broad in scale,very complicated in structure and the evolution process is tortu-ous.The structures include thrust nappe which is mainly composed of Paleozoic Erathem and the fold nappe that is mainly made up of Meso-Cenozoic.The rule of its tectonic transports and emplacements is frontal imbrication. Based on the paleomagnetic and geological structure data of the structural belt,the belt has become a part of North China Plate since the beginning of Devonian,and it con-nected with Tarim Plate along Altun Fracture after Permian.The napping distance of the nappe structural belt has reached more than 200 km since Permian,of which about 100 kmwas done after Jurassic.In the course of its formation and development,the belt underwent NE-SW direc-tional tension from Z to O₂,NE-SW directional compression from O₃ to P,counterclock-wise rotation from T to J,and near SN directional compression after J.The nappe belt has controlled the range,basement shape,type of deposits and condi-tions for organic matter evolution and hydrocarbon preservation of the basin.Hydrocar-bon exploration areas thus can not be restricted in the front part of the nappe belt,but should also further extend into its inner part so as to discover oil pools in the nappe andthe overriding belt;hydrocarbon resources could not noly be found in Jurassic-Cretaceous Systems,but also in Permo-Carboniferous sediments.