塔里木盆地西南部齐姆根逆冲推覆构造的特征及其与油气的关系

齐姆根逆冲推覆构造带位于喀什凹陷与叶城凹陷之间的齐姆根凸起上,由3个与盆地边缘大体平行的次级逆冲构造带组成,即阿尔塔什推覆构造带、科克然达坂-希根纳孜吉勒嘎推覆构造带、库斯拉甫推覆构造带。3个次级逆冲构造带分别将石炭系—二叠系推覆在侏罗系、白垩系及古近系—新近系之上,将泥盆系推覆在石炭系—二叠系之上,将元古宙变质岩及古生代花岗岩逆冲在泥盆系及泥盆系之上不整合覆盖的侏罗系之上。根据推覆体地层的叠置关系及逆冲断层的发育特征,齐姆根逆冲推覆构造带是由北向南演化的、后展式发展的逆冲推覆构造系统,其间发育横向调节的走滑断层。逆冲推覆体系的主体断裂沟通了源岩与储层,推覆体下盘发育的大型背斜圈闭为油气聚集提供了有利的场所,运聚条件的合理配置为该区油气勘探提供了良好的前景。

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 overthrust belt is an overthrust system characterized by south-directed evolution and piggyback propagation, in which strike-slip 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.