Evaluating the role of syn-thrusting sedimentation and interaction with frictional detachment in the structural evolution of the SW Tarim basin, NW China: Insights from analogue modeling

- Syn-thrusting sedimentation results in the deformation front shifting forwards.
- Thick syn-thrusting sedimentation can activate a potential frictional detachment.
- Thin syn-thrusting sedimentation favors development of backthrusts.
- Thick syn-thrusting sediments strongly control structural evolution in the SW Tarim.

The structural evolution of the fold-and-thrust belt in SW Tarim Basin, NW China is poorly understood as the region is covered by thick Pliocene-Quaternary conglomerate, which significantly decreases the quality of seismic images. We here improve the understanding of the thrust belt evolution with an investigation using analogue modeling on the deformation mechanism based on a case of real geological section, in which we focus on the impact of syn-thrusting sedimentation on the structural style and evolution. The results show that syn-thrusting sedimentation significantly increases the distance and rate of foreland propagation, resulting in a much broader fold-and-thrust belt. The modeling results also suggest that the fold-and-thrust belt exhibits different structural patterns under different syn-thrusting sedimentary conditions. In the case of thick syn-thrusting sediments, a frictional detachment layer of mudstone acts as décollement and the fold-and-thrust belt develops a duplex pattern in the hinterland. In the case of thin syn-thrusting deposits, the belt develops a pop-up structure with backthrusts in the foreland region which cut through the detachment layer. The striking similarity between the model with thick syn-thrusting sediments and the real geologic section implies that the overlying thick Pliocene-Quaternary sediments play a major role in shaping the structure pattern in the fold-and-thrust belt of SW Tarim Basin.