Characteristics of Qimugen thrust nappe structure in the southwestern Tarim basin, Xinjiang, China, and its relationship with hydrocarbon

The Qimugen overthrust belt, located in the Qimugen sub-uplift between the Kashi sub-depression and Yecheng sub-depression, is composed of three thrust belts of smaller order subparallel to the basin margins, i.e. the Aratax overthrust belt, Kekeran Daban-Xigennazijilega overthrust belt and Kosrap overthrust belt. The three smaller overthrust belts thrust the Carboniferous-Permian over the Jurassic, Cretaceous and Tertiary and also the Devonian over the Carboniferous-Permian and thrust Proterozoic metamorphic rocks and Paleozoic granite over the Devonian and the Jurassic that unconformably overlies the Devonian. According to the superimposition relationships of the strata of the nappes and features of thrusts, the Qimugen overtbrust belt is an overthrust system characterized by south-directed evolution and piggyback propagation, in which strikeslip faults that play a role of lateral readjustment are developed. The principal faults in the overthrust system connect source rocks and reservoirs, and large anticlinal traps in the downthrown block of a nappe provide favorable sites for hydrocarbon accumulation. The rational disposition of migration and accumulation conditions offer good prospects for petroleum exploration in the area.