西秦岭迭山西北部冰川地貌分布及其特征

Distribution and Features of Glacial Landforms in the Northwest of the Die Shan,West Qinling Mountains

迭山西北部位于青藏高原的东缘,属西秦岭山脉的西段.在海拔3 700m以上保存有类型较为齐全的冰蚀地形(冰斗、刃脊、U形谷、悬谷、粒雪盆、鲸背岩与基岩磨光面等)与冰碛地形(侧碛垄与终碛垄).采用野外考察、遥感影像解译与填图等方法对该区的冰川地貌分布及其特征进行了探讨.基于研究区冰川地形分布与特征,结合青藏高原现代的抬升速率、邻近山地冰川地形的年代学资料以及其他古环境研究成果进行综合分析得出:该区的古冰川发育于末次冰期,末次冰期最盛期是其最主要的形成期.冰川最盛时面积约38km2,为具有暖底性质的冰帽冰川.

The northwest of the Die shan, as the western segment of the Qinling Mountains, is located in the eastern margin of the Qinghai-Xizang Plateau. Glacial erosional and depositional landforms, including cirques, U-shaped valleys, hanging valleys, palaeo-firn basins, whaleback rocks, polished bedrocks, and lateral and end moraines are well preserved in this mountainous area above 3 700 m a.s.l. Remote-sensing techniques and field mapping were applied to study the distribution and features of glacial landforms in this area. Based on the distribution and features of glacial landforms, considering the present uplift speed of the Qinghai-Xizang Plateau, the available dating data of the glacial landforms in the Dalijia Mountain and the data of the palaeoenvironment in the neighboring areas, the glacial landforms are considered to be formed in the last glacial cycle, especially during the Last Glacial Maximum. The ancient glacier was an ice cap with a maximum area of about 38 km2. Abundant whaleback rocks that present at about 4 200 m a.s.l. indicate that the ancient ice cap had a warm bottom.