南天山库玛拉克河出山口第四纪以来河谷变迁初探

Preliminary Study on Valley Variation in the Mountain Pass of Kumalake River of South Tianshan Mountain Since the Quaternary

综合分析库玛拉克河出山口地质构造发育历史、河床沉积特征,以及钻孔所揭露的河谷两岸古河床沉积高程特征、出山口以外阶地发育高程规律等地质地貌资料,并将结果与研究区岩溶发育规律进行对比后,确定了库玛拉克河谷的垂向演变特征,认为第四纪以来该河谷经历了七次稳定-下切旋回。利用各阶地沉积物的热释光测年分析结果,对河谷的下切速率进行了计算,表明在70～80ka之前河谷的下切速率最快,达到8.2m/ka。在河谷下切的过程中,河谷同时不断向左岸进行迁移。

The geological structure and sedimentary features of riverbed in the mountain pass of Kulamake River were used to in- vestigate the valley variation in the area. The analysis of tectonic development history, the characteristics of ancient riverbed sed- iment elevation based on the drill-hole data, and the terrace development elevation in the mountain pass were used to determine the stable-erosive periods of the riverbed since the Quaternary, which was compared with the karst development characteristics in the study area to identify the vertical valley variation. The results indicated that there are seven stable-erosive periods for the valley since the Quaternary. According to the thermoluminescence dating analysis on the terrace sediments, the erosive rate of the valley was calculated,which showed that the valley has the fastest erosive rate of 8.2 m/ka before the time period of 70 to 80 ka. In addition, the valley continued to move to left side of valley during the valley erosion process.