中文摘要：

喜马拉雅山珠穆朗玛峰-希夏邦马峰地区是青藏高原南部现代冰川集中发育区之一,古冰川遗迹亦十分丰富,是研究第四纪青藏高原冰川形成和演化的关键区,一直备受地貌和第四纪环境研究者的关注.应用原地宇宙核素10Be暴露年龄测试技术,对采自希夏邦马峰西北佩枯岗日拉曲谷地冰碛垄上的冰川漂砾进行年代学研究;结合冰川地貌分析方法,对古冰川平衡线高度（ELA）和气候特征进行探讨.结果表明：末次冰期时,拉曲谷地冰川扩张,发育了山麓冰川,拉曲Ⅰ冰川面积99.9 km2,平衡线海拔5 620 m;拉曲Ⅱ冰川面积97.6 km2,平衡线海拔5 600 m;与现代平衡线高度相比,拉曲Ⅰ和拉曲Ⅱ的平衡线分别下降380 m、400 m.拉曲在末次冰期存在多次冰进,拉曲Ⅰ的10Be暴露年龄在42.1～22.3 ka;拉曲Ⅱ的10Be暴露年龄在18.6～14.8 ka.根据地貌法恢复末次冰期拉曲Ⅰ平衡线高度的温度为-10.7℃,拉曲Ⅱ为-10.6℃,降水量分别为251～461 mm和261～480 mm,显示出当时雪线高度的温度状况和现代冰川雪线高度的温度状况接近,但是降水比现在少得多,冰川气候类型为亚大陆型,印度季风减弱带来的水气变少.

英文摘要：

Xixabangma-Qomolangma（Xixabangma-Everest） region is an intensively glaciation centre in monsoonal Himalayas,and relic glacial landforms are widely distributed in the glacial valley.Relatively well preserved geomorphic and sedimentary sequences make the region to be a key region for reconstructing Quaternary glaciations and environmental evolution in the Tibetan Plateau.Based on field geomorphologic surveying and 10Be terrestrial cosmogenic nuclide（TCN） exposure dating,Quaternary glacial events in the Laqu valley on the northern slopes of Mount Xixabangma are examined;the equilibrium line altitude（ELA） and their climatic implication are discussed.The glacier expanded down to pediment and became pediment glacier in Laqu Valley during the Last Glacial.The glacierized area was 99.9 km2 and the equilibrium line altitude was 5 620 m for Laqu I;the glacierized area was 97.6 km2 and the equilibrium line altitude was 5 600 m for Laqu II.Compared with the ELA at present,the equilibrium line altitude of Laqu I and Laqu II declined 380 m and 400 m,respectively.There were several glacial advances in the Laqu Valley during the Last Glacial,10Be exposure age is 42.1～22.3 ka for Laqu I,and 10Be exposure age is 18.6～14.8 ka for Laqu II.Based on geomorphologic methods,the climate at ELA of Laqu I and Laqu II were reconstructed,and the temperature was-10.7 ℃ and precipitation was 251～461 mm for Laqu I;the temperature was-10.6 ℃ and precipitation was 261～480 mm for Laqu II;the temperatures at the ELA are considerably close to that at present,but the precipitations are much less than that at present,showing the glacier belonged to sub-continental type during the Last Glacial with weak Indian Monsoon.