摘要
阿尔泰山喀纳斯河流域在第四纪期间发生过多次冰川进退,丰富的侵蚀与堆积地貌为区域地貌演化过程分析提供了重要依据,同时,该区的第四纪冰川作用对全球环境变化研究具有重要的科学意义。通过对喀纳斯湖口以下主谷内古冰川地貌的实地考察,测定不同地段多级U型谷底（台地）的海拔高度以及冰川漂砾的上限与分布位置,并对主谷内不同地段不同期次的冰碛物进行电子自旋共振（ESR）测年,研究发生在主谷内的古冰川作用系列、规模及演化过程。结果表明：喀纳斯湖到驼颈湾地区的谷地中主要发生过4次冰川作用,时代分别对应中梁贛冰期（MIS12）、MIS8/10、倒数第二次冰期（MIS6）以及末次冰期。末次冰期冰川作用又可细分为3个阶段,分别对应MIS4、MIS3中期与MIS2;根据三级U型谷的分布特征推断,古冰川作用规模呈现渐次变小的规律,自冰川站至下游接近冰川末端,中梁贛冰期时冰川厚度达50～395 m,覆盖范围包括主谷及两侧的山梁和支谷,延伸的长度和宽度都最大,MIS8/10以及倒二冰期时的厚度分别在102～199 m和88～269 m之间,冰川末端到达驼颈湾附近;鸭泽湖附近坡地上保存完好的多级台地,说明发生在河谷内的古冰川活性大,流动性和连续性较强,具有温冰川的性质;喀纳斯主谷有明显的不对称性,与局部小气候和地形对冰川的发育影响有关。
Multiple glacial advances/retreats have occurred in Kanas region of the Altay Mountains. Glacial erosive and accumulative landforms are not only very important for the analysis of the regional geomorphological process but also meaningful for the research on global change. According to the field investigation on the Quaternary geomorphology in the lower part of the Kanas Lake outlet in the main valley, this paper measured the altitude of multiple level U- shaped valley in different regions and confirmed the highest limit of glacial boulders and their spatial distribution. Using the electron spin resonance（ESR） method, we dated the glacial tills of the different moraines preserved along the main valley. Results of the glacial sequences, extent and glacial geomorphological process showed that four glacial advances occurred the lower part of the Kanas valley. Compared with the previous research results, these glaciations can be assigned as the Zhonglianggan glaciation, corresponding to the marine isotope stage 12（MIS12）, MIS8/10 glaciation, Penultimate glaciation（MIS6）, and the last glacial cycle（LGC）. LGC glacial advance can be further divided into three stages which correspond to MIS 4, 3, and 2. Based on the distribution of the three level U-shaped valleys, we concluded that the extent of glaciers decreased with time. The thickness of the glacier during Zhonglianggan glaciation was 50-395 m from the Glacial Station to the end of the glacier, and the length and width are also the largest at that time. The three- dimension extent showed that the glaciers were distributed in the main valley and on both sides of the ridges. The thickness was 102- 199 m and 88- 269 m during the MIS8/10 and the Penultimate glaciation, and the glacier reached near Tuojingwan. Well persevered multiple level U- shaped valley bottom on the eastern slope of the main valley near the region of Yazehu Lake indicated that the Quaternary glaciers have the warm glacier features such as strong activities, flowability and continuity. Clear asymmetry that occurred in the Kanas main valley showed that the development of the glacial valley was affected by regional climate and topography.
出处
《地理学报》
EI
CSCD
北大核心
2015年第5期739-750,共12页
Acta Geographica Sinica
基金
国家自然科学基金项目(41271093
41230743
40971010)~~
关键词
阿尔泰山
喀纳斯河谷
晚第四纪
冰期系列
地貌过程
Altay Mountains
Kanas river valley
late Quaternary
glacial sequence
geomophological process
