Along-strike structural variation in a salt-influenced fold and thrust belt: Analysis of the Kuqa depression

Abstract

The Kuqa depression is associated with complex salt structures. Variation in fold geometries and subsalt fault activities were investigated using parallel cross-sections to reveal detailed along-strike variations within the Keshen 5 segment and their controlling factors. Along-strike variations were identified in both suprasalt and subsalt units. Linkages, such as the location of a transfer zone, were apparent, while the distribution of variations above and below the salt layer were decoupled. The results indicate that the pre-existing salt wall is the key factor driving along-strike variations because it acts as a weak zone that influences deformation propagation. Suprasalt structural variation results in different sediment depths, which have a significant impact on subsalt fault activity. In the eastern segment, fault activity decreases from the hinterland to the basin. In contrast, owing to the pre-existing salt wall and deep sedimentation near the hinterland in the western segment, the fault beneath the salt wall is characterized by maximum displacement. This study reveals the connection between suprasalt and subsalt deformation and the role of that a salt diapir plays in along-strike structural evolution variations for the Keshen 5 segment of the Kuqa depression. These findings are relevant for understanding along-strike deformation propagation and structural variation in other fold and thrust systems.