西南天山乌什北山高山峡谷地貌形成过程

THE LANDFORM FORMATION PROCESS OF ALPINE-GORGE IN BEISHAN,WUSHI COUNTY,SOUTHWESTERN TIANSHAN

地貌演化过程受大地构造及其规律的控制。本文通过对西南天山乌什北山地区滚滚铁列克河第四纪沉积和侵蚀地貌的观测,结合已发表的地层年代学研究,恢复了中更新世和全新世两期侵蚀地貌演化过程。中更新世地貌切割深度达1870 m以上,远远大于全新世50 m的地貌切割深度,认为该地区的高山峡谷地貌形成于中更新世。西南天山普遍发育的中更新世褶皱冲断构造,造成山体快速大幅隆升,是乌什北山高山峡谷地貌形成的主因。褶皱冲断构造向盆地方向扩展,导致山体向盆地方向隆升幅度减小,揭示了乌什北山地貌演化的空间规律。西南天山第四纪构造隆升过程与地貌演化之间存在密切关系。

The geomorphological evolutionisbasically influenced by the tectonic and its regular pattern. Based on the observation of Quaternary deposit and erosional landform of Gunguntielieke river valley in Beishan, Wushi County, Southwest Tianshan, combing with the published stratigraphic chronology, the evolution of erosive geomorphic in Middle Pleistocene and Holocene are reproduced. In Middle Pleistocene, the geomorphological cutting depth is more than 1870 m, which is much deeper than 50 m in Holocene and it is believed that the alpine- gorge in this area was formed in Middle Pleistocene. Generally developed Middle Pleistocene fold thrust structure in Southwest Tianshan, resulting in the rapid and substantial mountainuplift, is the main cause of the alpine-gorge geomorphology in Beishan. The fold thrust structures extended to the basin, which led to the decrease of amplitude of the uplift of the mountain to the basin. It reveals the spatial regularity of the geomorphological evolution in Beishan. There is a close relationship between the process of Quaternary tectonic uplift and geomorphological evolution in Southwest Tianshanmountainaccording to this stuty.