滇西北山地末次冰期冰川发育及其基本特征

对滇西北海拔4 000~4 500 m 山地的第四纪冰川发育和平衡线高度进行了研究. 结果表明: 古冰川发育主要依托海拔4 000~4 300 m的夷平面，早中期发育小型的冰帽以及流入四周谷地的山谷冰川，晚期主要发育规模较小的冰斗冰川. 冰川主要发育期为末次冰期，古冰川平衡线、山体最高峰以及夷平面的高度显示，冰川发育所依托的夷平面在末次冰期时超过古平衡线，二者差值为50~400 m，为冰川发生提供了良好的地形与地势条件. 冰川规模演化表明，滇西北地区多处山地MIS 3中期的冰川规模大于末次冰盛期（LGM），可能与MIS 3中期较强南亚季风带来较丰富的降水有关. 古气候研究资料以及研究区的冰期系列表明，滇西北海拔4 000~4 500 m山地末次冰期的冰川作用是构造和气候相耦合的结果.

Features of the glaciation during the Last Glaciation in northwestern Yunnan Province

Investigation of Quaternary glaciation in the mountains in northwestern Yunnan Province, ranging from 4 000 to 4 500 m a.s.l., indicates that the glaciation mainly depended on the planation surface from 4 000 to 4 300 m a.s.l. Glaciers were small ice caps and valley glaciers during the early and middle stages, and limited cirque glaciers during the late stage of the Last Glaciation. Glacial advance mainly took place during the Last Glaciation. Analyzing the equilibrium line altitudes in the Last Glaciation, summits of the mountains and the planation surface altitudes indicates that the planation surfaces, on which glaciers in the Last Glaciation depended, were 50-400 m higher than ELA. The altitude between 4 000 and 4 500 m provided the beneficial height for the glaciers development. Analyzing the evolution of glacial extent shows that the glacial extent during the middle of MIS 3 was larger than that in the Last Glaciation Maximum (LGM). It is believed that the glacial advance during the MIS 3 was due to both plentiful precipitation and low temperature. Data of paleo-temperature and paleo-precipitation and Quaternary glaciation investigation reveal that the Last Glaciation was resulted from climate change and tectonic movement.