Tectonic Analysis on Aqia Fault Belt in the Western Tarim Basin

The Aqia fault belt,which occurs as the boundary of the Awati Sag and Bachu Fault-Uplift in the western Tarim Basin,is mainly made up of Aqia fault and Qiaolaimaiti fault.Based on seismic interpretation,it can be divided into three parts: the west,the middle and the east sections.The west section is a single basement-involved thrust fault which dips towards the Bachu Fault-Uplift.Comparatively,the middle section has a Y-shape tectonic style and begins to show the wedge-shaped thrust features,which develops not only the main Bachu-inclining fault mentioned above,but also a recoil fault with a reversed inclination.In the east section,the main Bachu-inclining fault stopped growing at Mid-Cambrian,with the displacement above completely absorbed by the Awati-inclining recoil fault,which finally forms the typical wedge-shaped thrust structures.A series of Quaternary normal faults have developed on the upper fault plate in the west and middle sections.According to the research,we conclude that there exist mainly two stages of fault tectonics in the Aqia fault belt: the deep basement-involved thrust fault zone and the shallow overlaid normal faults series.The former started to form 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 developed only in the west and middle sections of the Aqia fault belt.