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Abstract:
Constraining the Cenozoic uplift of Tian Shan is important for assessing the impact of the India-Asia collision to Central Asia. Here we estimate the uplift history of the Bogda Shan, northeastern Tian Shan, using a thermo-kinematic model which is constrained by previously reported apatite fission-track thermochronological data. By assuming that the growth of the mountain range propagates towards the basin as a classic critical wedge model, we show that the observed variation in the cooling ages on the mountain flank can be used to provide constraints on the timing and rate of the deformation along a series of south dipping thrust faults, which all root on a low-angle décollement. Inverse modeling confirms previous findings from thermal history models that the Cenozoic uplift in the Bogda Shan initiated during the Paleogene, no later than ~40 Ma. Since the early Miocene (~23 Ma), locus of uplift has expanded to the current southern margin of the Junggar Basin. Our kinematic model of the deformation of the Bogda Shan suggests a temporal stability in the shortening rate of the northeastern Tian Shan over the period of the India-Asia collision during the late Cenozoic.
