Tectonic Evolution Series of the Niaoshan Structure Belt in the Bachu Uplift,Tarim Basin,and Its Significance in Hydrocarbon Exploration

Niaoshan structure belt,located at the junctional zone between the southwest Depression of Tarim Basin,and Bachu Uplift,and to the western margin of the Hetianhe gas field,is an important structure unit within the Tarim Basin.By using the drilling data and seismic profiles,the Niaoshan structure belt can be divided into three sub-structures: the main Niaoshan structure,the east Niaoshan structure,and the north Niaoshan structure.Eight tectonic evolution stages can be divided based on the unconformity data and analysis of the balanced section.The major Niaoshan structure used to be part of the Mazhatage structure and separated from it because of rip-up fault-the east Niaoshan fault-resulted from differential stress.The north Niaoshan fault was developed within Niaoshan,Mazhatage and Gudongshan under the influence of late Himalayan movement at the late Holocene Epoch.Therefore,the Niaoshan structure has good petroleum geological conditions,with the east Niaoshan structure as the most potential zone;the main Niaoshan structure is also a potential target for oil exploration.