塔里木盆地吐木休克构造带断裂构造分析

吐木休克断裂位于塔里木盆地西部,是一条大型基底卷入型断裂构造带,构成塔里木盆地次级构造单元阿瓦提凹陷和巴楚断隆的分界。根据系统的地震资料解释,可以将吐木休克断裂分为西段、中段和东段3部分,各段构造特征有所差异。西段,为单一的基底卷入型高角度逆冲断层,倾向巴楚断隆; 中段,除倾向巴楚断隆的主冲断层外,倾向相反的反冲断层越来越清晰,楔状冲断构造的轮廓逐渐显现出来。同时,在断层上盘还发育第四纪正断层; 东段,倾向巴楚断隆的主冲断层,向上断至中寒武统,未断开中寒武统以上的地层,其冲断位移量完全为倾向阿瓦提凹陷的反冲断层所吸收,形成典型的楔状冲断构造。根据地震资料解释,认为吐木休克断裂带主要存在两期断裂构造:深部高角度基底卷入型逆冲断裂带和其上叠加的浅部正断层。前者形成于库车组沉积前,在库车组沉积期间持续活动,并在新近纪晚期定型; 后者是本次研究首次发现的,形成于第四纪早中期,仅发育在吐木休克断裂带的中部。

Tectonic analysis on Tumuxiuke fault belt in the western Tarim Basin

The Tumuxiuke fault belt,which locates in the western Tarim Basin,is a large-scale basement-involved fault zone and forms the boundary between the Awati Sag and Bachu fault-uplift(sub tectonic units of Tarim Basin).Based on systematic interpretation on seismic data,three sections of different tectonic features can be divided:the west,the middle and the east section.In the west section,there only develops a basement-involved high-angle thrust fault which dips towards the Bachu fault-uplift; while in the middle section,besides the main Bachu-inclining fault mentioned above,a reversed-inclination recoil fault becomes increasingly clear and gradually draws the outline of wedge-shaped thrust structures.Meantime,on the upper plate of the recoil fault,a series of Quaternary normal faults develop; however,in the east section,the Bachu-inclining main fault has its top stopped at Mid-Cambrian,while the unbroken strata above Mid-Cambrian have their thrust displacement completely absorbed by the Awati-inclining recoil fault,which finally make up of the typical wedge-shaped thrust structures.According to the seismic interpretation,we conclude that mainly two generations of fault tectonics exist in the Tumuxiuke fault belt:the deeper high-angle basement-involved thrust fault zone and the shallower overlaid normal faults.The former formed in early Neogene and finally stabilized in Late Neogene; the latter is a new discovery in this paper which formed in the Early-Middle Quaternary and it only developed in the middle section of the Tumuxiuke fault belt..