Faulting and folding on the margins of intermontane basins play important roles in accommodating the Cenozoic deformation of the Tian Shan, an intracontinental orogen in central Asia. In the eastern Tian Shan, the southern margin of the elongated Kumysh Basin is bounded by a NE dipping thrust fault, the Kumysh Fault. We report the first investigation of the slip rate of this fault, which is constrained at two sites by profiling the faulted topography and dating the abandoned alluvial fan surfaces. We obtained the topographic data using the satellite stereo imagery and dated geomorphic units using cosmogenic nuclide (¹⁰Be) exposure ages and optically stimulated luminescence methods. The results from Monte Carlo simulations of the data suggest an average dip‐slip rate of ~0.35 mm/yr on the Kumysh Fault since 50–60 ka. The “best fit” models indicate an increase after ~5 ka, which may be apparent or caused by the most recent earthquakes. Structural analysis of the displaced strata on a trench wall suggest at least 2.8 m dip offset caused by the late Holocene earthquakes, which is similar to the heights of fault scarps (1.8–2.9 m) on the second youngest alluvial fans (5.6–5.2 ka). Using the dip angle of ~25–40°, we estimate ~0.31 mm/yr shortening rate across the Kumysh Fault during the late Quaternary. By comparing our results with other estimates published in the easternmost Tian Shan, we suggest that deformation within intermontane basins may accommodate up to 50% of the total late Quaternary shortening rate between the Junggar and Tarim blocks, with only the remaining half accommodated by the main, range‐bounding thrusts.

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山区间盆地的主动冲断：天山东部的库米什断层

山地间盆地边缘的断层和褶皱在适应中亚大陆内造山带天山的新生代变形中起着重要作用。在天山东部，拉长的Kumysh盆地的南部边缘以NE倾覆逆冲断层Kumysh断层为界。我们报告了对该断层的滑动率的首次调查，该断层的滑动率在两个位置都受到限制，方法是对断层地形进行剖析，并对废弃的冲积扇面进行测年。我们使用卫星立体图像获得了地形数据，并使用了宇宙成因核素（¹⁰是）曝光年龄和光学激发的发光方法。蒙特卡罗模拟数据的结果表明，自50-60 ka以来，库米什断层的平均倾滑速率约为0.35 mm / yr。“最佳拟合”模型表明〜5 ka之后增加，这可能是明显的，也可能是由最近的地震引起的。对沟槽壁上位移层的结构分析表明，由全新世晚期地震引起的倾角偏移至少为2.8 m，这与第二年轻的冲积扇（5.6-5.2 ka）的断层陡峭高度（1.8-2.9 m）相似。 ）。使用约25–40°的倾角，我们估计第四纪晚期整个Kumysh断层的〜0.31 mm / yr缩短速率。通过将我们的结果与在最东端的天山发表的其他估算结果进行比较，