北天山博乐盆地南缘勒塔干褶皱晚第四纪构造变形

研究天山地区活动逆冲断裂、褶皱对于认识整个天山再生造山带的隆升和地震危险性评估具有重要意义。以天山北麓博乐盆地南缘库松木楔克断裂东段勒塔干褶皱为研究对象，通过无人机航拍提取高精度DEM和野外实地调查结果，将勒塔干背斜东部迪里克河附近的洪积扇分为5期，从新到老分别为T1、T2、T3、T4、T5。其中，T4洪积扇完整记录了褶皱的变形历史，其后翼褶皱陡坎高度为（8.1±0.6）m。自T4洪积扇废弃以来，勒塔干断层的滑移量为（33.0±2.6）m。T3洪积扇仅发育在迪里克河出水口处，即勒塔干背斜北侧，（16.9±0.2）m的断层陡坎高度揭示了自T3洪积扇废弃以来，控制背斜形成的逆断层发生了21.4～21.7 m的滑动。通过与相邻地区洪积扇期次进行对比，认为T4洪积扇的废弃年龄为（74.01±6.14）ka，勒塔干背斜下断坡晚第四纪滑动速率为（0.45±0.05）mm/a，勒塔干褶皱晚第四纪地壳缩短速率为（0.37±0.04）mm/a。

Late Quaternary Tectonic Deformation of the Latgan Fold in the Southern Margin of the Bole Basin,North Tianshan

The study of active thrust faults and thrust folds in the Tianshan ranges is of great significance for understanding the uplift characteristic and earthquake hazard for the Tianshan. This paper focuses on the Latgan fold in the eastern segment of the Kusongmuxieke fault on the southern margin of the Bole Basin in the North Tianshan. Based on the high-precision DEM extracted by drone aerial photography and field surveys, we divided the alluvial fans which developed along the Dilik River in the eastern part of the Latgan fold into five generations, T1-T5 from young to old. The alluvial fan T4 completely records the deformation history of the fold. The height of the fold scarp of T4 is 8.1±0.6 m. Since the abandonment of the T4 alluvial fan, the dip-slip offset of the Latgan fault is 33.0±2.6 m. The T3 alluvial fan is only developed at the outlet of the Dilik River, that is, on the north side of the Latgan anticline. The 21.4-21.7 m dip-slip offset can be derived from the 16.9±0.2 m fault scarp since the T3 alluvial fan was abandoned. By comparing with the alluvial fan in adjacent areas, we can determine the abandoned ages of the T4 alluvial fan is 74.01±6.14 ka. Based on the lower dip-slip offset and T4 alluvial fan abandonment ages, the late Quaternary slip rate of the Latgan anticline and crustal shorting are 0.45±0.05 mm/a and 0.37±0.04 mm/a, respectively.