Characteristics and deformation mechanism of salt-related structures in the western Kuqa depression, Tarim basin: Insights from scaled sandbox modeling

•Compressive salt structures in Kuqa basin are analyzed using scaled sandbox models.•The variable salt basin width results in differential salt-related structures.•Early passive diapir controls the later compressive deformation.•A long-distance allochthonous salt sheet is evolved from early passive diapir.

Three scaled analog (sandbox) models are constructed to simulate the evolution of thick-skinned shortening on broad and narrow salt basins. These models simulate the evolution of the Cenozoic salt (salt-related) structures in the westernmost Kuqa salt-bearing depression (Quele area), Tarim basin. The formation mechanism and the controlling factors of structural deformation in this area are investigated and discussed systematically. Model results show that the variable depositional width of the salt basin has a major controlling influence on the differential structural deformation in different longitudinal segmentations from east (broad) to west (narrow) in the western Kuqa depression (Quele area). Model results also demonstrate that the early salt structure (salt diapir) has an important controlling role on the subsequent compressional structural deformation. The pre-existing thin overburden Quele diapir, which acts as a stress concentration zone during the subsequent shortening, is deformed to the Quele salt nappe. On the basis of the model results, it is suggested that the formation of the long-distance Quele allochthonous salt sheet is related with the pre-existing Quele diapir, which displaces up paralleling the hanging wall and flows to the surface during the subsequent shortening.