塔里木盆地西部巴楚断隆南界断裂带的主要特征 和构造演化

塔里木西部巴楚断隆的南界断裂带晚中生代开始形成,内部结构十分复杂。在逐条介绍各断裂特征的基础上综述了该断裂带的主要几何学和运动学特征。该断裂带经历了白垩纪、中新(—上新)世和更新(—全新)世3期重大的冲断,前者与巴楚断隆北界断裂的演化不同步,后两者则与北界断裂带同步发育。白垩纪、更新(—全新)世的向北冲断与西昆仑山前褶皱冲断系的向北扩展有关,中新(—上新)世的向南(西)冲断受南天山褶皱冲断系向南扩展的制约。这3期冲断都伴有剪切变换构造发育,尤其是白垩纪的北西向右行走滑断裂,在造就南界断裂带的分段性和复杂面貌中起了重要作用。

Main features and structural evolution of southern boundary fractural zone of the Bachu fault-rise in western Tarim Basin

The Bachu fault-rise is a sub-order tectonic unit of the Tarim Basin, and its southern boundary, created since Late Mesozoic, is a complicated fractural zone. Based on a brief introduction to each fault, this paper synthetically described main geometric and kinematic characteristics of the southern boundary fractural zone. The fractural zone experienced three major thrusting events, which occurred in Cretaceous, Miocene (-Pliocene) and Pleistocene (-Holocene) respectively. The Cretaceous thrusting was developed only along the southern boundary, and the northern boundary, such as the Tumxuk fracture, acted as a boundary between the Bachu fault-rise and the Awati sag in Jurassic-Cretaceous, instead of thrusting. The Cenozoic thrusting events synchronously occurred along both the southern and northern boundary fractural zones of the Bachu fault-rise. An analysis of basin-orogenesis coupling reveals that the northward thrusting in Cretaceous and Pleistocene (-Holocene) should have been related to northward expansion of the foreland fold-and-thrust belt of West Kunlun, while the south(west)ward thrusting in Miocene (-Pliocene) might have been coupled with southward expansion of the South Tianshan fold-and-thrust belt. All of the three generations of thrusting were accompanied by the shearing fractures, which made up a transfer zone in the thrusting system. The Cretaceous NW-trending dextral strike-slipping fractures played an important role in the segmentation and complication of the southern boundary fractural zone of the Bachu fault-rise.