Abstract: The Kekeya fold-and-thrust belt (Kekeya FTB) at the front of the West Kunlun Range underwent multiple phases of
tectonic deformation and reworking during the Caledonian, Indosinian, and Himalayan periods. Unraveling the mechanisms of superimposed deformation in the southwestern Tarim Basin could provide crucial constraints for seismic interpretation and structural modeling. This study systematically investigates the two-phase superimposed deformation of the Kekeya FTB using analogue modeling. We designed experimental series with varying décollement configurations to evaluate the effects of tectonic superposition, décollement rheology, and Cenozoic syntectonic growth strata. The main conclusions are: (1) Syntectonic growth strata facilitate the propagation of deformation toward the foreland by inhibiting the surface breakthrough of deep-seated faults. This process enhances the decoupling effect of shallow décollements, allowing for more efficient strain transmission to the distal foreland; (2) Second-phase faults exhibit strong structural inheritance, preferentially reactivating pre-existing first-phase faults; (3)
Comparisons between experimental results and geological cross-sections demonstrate that a coupled model involving a deep brittle and shallow ductile décollement under two-phase compression accurately reproduces the structural geometry of the Kekeya FTB. This deformation results in a stratified architecture comprising a deep basement imbricate fan system and a shallow passive-roof thin-skinned system. 

Key words: West Kunlun piedmont, Kekeya FTB, superimposed deformation, analogue modeling, décollement