Abstract:The subsalt structural geometry in front of the north structural belt is quite different in eastern and western segments of the Kuqa depression. The subsalt structure is composed of an imbricate thrusting belt in the Kelasu structure of the western segment, while it is a faulted anticline in the Dongqiu structure of the eastern segment. In this paper, based on seismic interpretation, five discrete element models are designed to explore the influence of pre- existing faults, syntectonic sedimentation and properties of salt layer on the structural geometry and evolution of fold- and- thrust belts, as well as the causes behind the different structural features of the eastern and western segments in the Kuqa depression. The simulation results show that the deformations of units above and below the salt layer are decoupled. A pre- existing fault can affect the deformation propagation, causing the differences in subsalt wedge shape, fault numbers and suprasalt structural geometry. Syntectonic sedimentation could enhance the deformation decorrelation above and below the salt layer, while a stronger salt property decreases it. Comparing the simulation results with the structural features of the eastern and western segments in the Kuqa depression, we suggest that a pre- existing fault could be the controlling factor of the structural variations between eastern and western segments. In the eastern Kuqa depression, the location of pre- existing fault first deforms, forming the Dongqiu fault and the Dongqiu anticline above it. Besides, the pre- existing fault absorbs most of the shortening, and prevents the deformation from propagating forward, thus causing an out of sequence deformation propagation. In the western Kuqa depression, with no interruption from pre- existing fault, the deformation of subsalt units sequentially propagates forward and forms an imbricate thrusting belt.