STRUCTURAL ANALYSIS AND HYDROCARBON FORMATION HISTORY OF WUSHI-WENSU AREA IN THE MID-SOUTH TIANSHAN FORELAND THRUST BELT
南天山前陆冲断带中段乌什-温宿地区构造分析与油气成藏

The Wushi-Wensu area is an important transfer zone of the southern Tianshan foreland thrust belt, and has large oil and gas resources. Using outcrop, remote satellite pictures, seismic profiles and gravity data, we built a structural model of this area, restored it's evolutionary history, and further discussed it's gas and oil formation process. The results show that the structural style transforms laterally, and the area is comprised of two units. The northern part, Wushi sag, is a contractive fault depression, while the southern part, Wensu uplift, is a paleo-uplift controlled by basement-involved reverse faults. The main deformation occurred during late Oligocene to early Miocene and Pliocene to Quaternary, caused 13~21 km horizontal shortening with 14%~20% shortening rate and average shortening speeds of 0.56~0.9 mm/a. There are abundant traps, which are controlled by the evolutionary history of the Northern margin of the Tarim basin. The traps in the Wensu uplift formed earlier, and the traps in the Wushi sag formed later. The difference in trap evolution controlled the reservoir formation.