Salt-related Contractional Structure and Its Main Controlling Factors of Kelasu Structural Zone in Kuqa Depression: Insights from Physical and Numerical Experiments

Abstract

Salt-related contractional structures widely developed in the Kuqa depression of Tarim basin, northwest China, which have important influences on the hydrocarbon migration and accumulation. The Kuqa depression has the structural deformation feature of “whole compression, delamination deformation”. To investigate the mechanisms that govern the development of these structures, physical and numerical experiments are conducted. Similar material properties and boundary conditions were used in both modeling approaches. The simlation results show that the factors controlling salt-related structural deformation include mechanical stratigraphy, differential loading and boundary conditions. Salt bed play a significant role in the development of the contractional structures, adjusting the deformation of suprasalt bed and subsalt bed. In general, decollement anticline developed in suprasalt bed, then fold-accommodation faults developed in the process of progressive deformation. The subsalt bed deformation is controlled by high-angle basement-involved thrust on which's footwall shortcut thrusts developed. On the whole, the salt-related structural deformation has the dynamics feature of whole compression, where suprasalt bed, salt bed and subrasalt bed were all deformed. The large detachment fault is not observed in the experiments, which indicates that whole compression dynamic deformation model is reasonable to decipher the structural features of Kelasu structure zone in Kuqa depression.