The Structural Styles And Petroleum Distribution In Bachu Area Of Tarim Basin

The main purpose of this paper is to discuss the characteristics ofunconformities, tectonic framework, fault and trap styles, evolution history,the relationship between tectonics and hydrocarbon and favorable prospects andtargets of Bachu faulted-uplift in Tarim Basin.Based on the studies of predecessors, we have divided the filled strataof Bachu-uplift into 6 firstorder stockwerkes and 21 secondorder stockwerkesmostly according to the uncomformities, the stratigraphic distribution, thedepositional sequence and reflection characteristic in the seismic profile ofBachu area.The tectonic framework of Bachu area presented as "west-eastdifferentiation and north-south dissimilitude". The uplift developed faultswith three aligements. On the longitudinal section, the deep fault systems aremore developed than the shallow fault systems. The west fault systems are moredeveloped than the east fault systems from the plane view. The NW faults piledup on the NW and NWW faults, and incised the NW faults. They formed later thanNW ones. On the whole, the tectonic framework has the characteristic of "theearly action was more intense than the late action and the degree of inversionis strong in the west but weak in the east".The structural styles were systematically studied. The faults weredominated by basement involved type. Different fault system and differentfaulted segments of the same fault had defferent structural styles anddifferent activity ages.The paper also studied the evolution based on the studies of structuralstyles. The uplift was an inherited palaeohigh evolved from Sinian Period andhas the same evolutional characteristic with Katake uplift in period ofpre-Mesozoic. In early Caledonian, middle Caledonian and late Hercynian, itwas a low uplift zone. The most important deformational event happened in lateYanshan movement and Himalayan movement.The fault movements were both inherited and anagenetic. Most of the faultsformed in middle Caledonian, late Caledonian, Hercynian and Himalayan.The zone evaluation of Bachu uplift was carried out according to the aboveanalysis. Three structural belts including Bashituo-Yasongdi fault zone, southof Kangtakumu-Selibuya fault zone and Tumuxiuke fault zone are the best zonefor exploration activity.