Thick-skinned Contractional Salt Structures in the Kuqa Depression, the Northern Tarim Basin: Constraints from Physical Experiments

Thick-skinned contractional salt structures are widely developed in the western Kuqa depression,northern Tarim basin.To understand the mechanisms that govern the development of these structures,physical experiments are conducted and the results show that they are largely governed by the activities of basement faults and the forming of paleo-uplifts and basement slopes.The model materials in this study are dry sand,vaseline and plasticene(or hard foam),simulating the suprasalt,salt,and subsalt layers respectively.The experiments show that,due to the activities of basement faults and the forming of the paleo-uplifts,salt bodies usually accumulate and thicken significantly on the middle top of the paleo-uplifts which are constrained by the pre-exiting boundary faults.The development of large-scale thrust faults and salt nappes is favored by the basement slops with larger dips.The experiments also conclude that differential structural deformation could occur between the subsalt and suprasalt layers because of the presence of salt layers.Their geometries and the locations of structural highs are different,despite of the great similarities in the uplifted areas.The pierced salt diapir is not observed in the experiments,which indicates that the contractional shortening does not effectively accelerate the development of the salt diapir.