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Abstract:
Enhanced knowledge of the Pamir salient formation can contribute to comprehending the tectonic evolution of Himalaya-Tibetan orogen. However, whether the Pamir salient formed along a linear or a curved southern Asian margin between the Tarim and Tajik cratons remains controversial. Likewise, the role of the two craton blocks during the evolution of the Pamir salient is unclear. Here we present three sandbox experiments exploring the effect of the geometry of the southern Asian margin, as well as the presence of Tarim and Tajik cratons. The results show that the highly curved shape of the Pamir salient, transpressional faults in its wings and strike-slip faults within its interior only form along a curved southern Asian margin. A westward-deflecting arcuate thrust wedge formed along the asymmetric curved southern Asian margin. Together with the Tarim craton and the Tajik craton, this wedge facilitated the westward transfer of materials in the Pamir, and resulted in the westward deflection of the velocity field in Pamir and the formation of the Tajik fold-thrust belt. The oblique slip of arcuate thrust wedge along the western edge of the Tarim craton generated the Kongur extensional system. Moreover, the Tarim and Tajik cratons concentrated deformation mainly along the non-cratonic continental margin and promoted the formation of transpressional faults surrounding the Pamir and the strike-slip faults within the Pamir.
