The Studying In Characters And Evolution Process Of Main Faults In Tarim Basin

Tarim basin has undergone many tectonic movements such as Caledonian, Hercynian, Indosinian - Yanshan and Himalayan movement, and developed many faults with different direction and different level, which are obviously directive in plane and layering in vertical. During evolution process, the number of fault grows from little to great; their activity gradually became stronger with configuration becoming complex. Finally they became the critical factor for the developing of the basin.The text has demonstrated that the fault development has undergone those movements: extensional movement in early Caledonian, thrust-motion from middle Caledonian to early Hercynian, rethrust-motion in late Hercynian, thrust-strike slip motion during Indosinian - Yanshan and thrust - decollement-strike slip in Himalayan. The fault's evolution ,which grew from unitary structure to dimensional structure, represents that there were many factors controlled the fault's evolution and resulted the complex features of fault today.Because of divergence in stress direction and property of several tectonic movements, the movements of faults in basin shows obvious multistage and inheriting. Among them, the fault of first or second degree show inhomogeneity and reversing in vertical and horizontal, some of them even have positive reversing and negative reversing. The faults in some part also had negative reversing during Himalayan movement.By interpreting of 20 basin crossed big profiles and 60 small profiles of Bachu, middle and north tarim, we first made out the fault system graph of early Caledonian in tarim. Through the distribution direction of fault, combining with periphery tectonic evolution as the background, the text found that there was a extensional stress ,whose direction is NE-SW, and concluded that the Aerjin fault may be the extensional down fault. Through research, the text proofs that the distribution of reef flat sediment was through the down fault, and drew the graph showing relation between fault and reef flat. Also, the text thought early down fault controlled Sinian and reef flat of Ordovician. The faults of middle Caledonian-early Hercynian were the product of reversing fault in early Caledonian. The reversing movement did not only cause the formalizing of uplift and depression in basin, but also controlled the distribution of paleo-uplifts and the development of later layers.The development of faults does not controlled the formation of local structure and traps, but also provided the passage for source rock and traps, because many oil gas field distributes through the faults. The multistage movement of faults causes the overriding of oil gas field in vertical. Being affected by faults, the hydrocarbon reservoir's accumulation also has character of multistage.