Basement-Involved wedge-shaped Structure of Aqia Fault in Northern Magin of Bachu Uplift in Northwestern Tarim Basin, Northwest China

The Tarim Basin records the history of deposition and deformation affected by the Indian—Eurasia collision during the Cenozoic. The seismic data shows that the faulted rigid Bachu uplift, central Tarim, is a paleo-uplift covered by Quaternary deposits. NW-striking Aqia fault, Qiaolaimaiti fault and Salambulake syncline and anticline between them were developed on the north margin of the Bachu uplift, northward adjacent to Awati depression. Many seismic lines and well data show that the Aqia fault is a deep basement-involved, south-dipping thrust fault, and the shallow structures are both Qiaolaimaiti north-dipping thrust fault and Salambulake fold. The Aqia fault cuts through the Precambrian basement to the Middle Cambrian evaporates and its displacements decrease from west to east. Salambulake anticline is a fault—propagation fold controlled by the Qiaolaimaiti fault which develops from the main decollement layer of the Cambrian evaporates. The south-dipping basement-involved fault,north-dipping cover-detached fault and Salambulake anticline forms a typical wedge-shaped structure in profile and a triangular structural belt in map view. The Aqia fault and the Salambulake fold extend northwestwardly into the Kelpin thrust belt and forms the NW-striking surface structures superimposed by northeastern-striking deformation. The growth strata indicates that NW-striking wedge-shaped structure formed during Eocene to Miocene, which extends northwestwards into the Kelping thrust zone formed in the Quaternary.