四川西南部小相岭东坡更新世冰川地貌与冰川沉积特征的初步研究

A preliminary research of Geomorphological and Depositional Features of Pleistocene Glaciations in the East Slope of Xiaoxianling Mountain in the Southwest of Sichuan Province

该地更新世冰川地貌类型有三级冰斗,槽谷、角峰、刃脊、4—6道侧碛堤、2—3道终碛垅等。冰碛成分全部来自冰川作用区,组构不发育。冰碛中砂含量较高,粉砂含量较少。电镜观察到石英砂上有压坑、“阶步”和擦痕。不同时代冰碛物的化学元素迁移不很明显。伊利石是冰碛中的主要粘土矿物。

There exist three steps of cirques, troughs, four to six lines of lateral moraines, pyramids aretes and end moraines, etc. The first step of cirques have an average altitude of 4150 m a.s.L The second step 3980 m and the third 3710 m a.s.L The lateral moraines near hillslope are larger, higher and older than those away from valleys. In the same valley, lateral moraine on the north side of hills has a larger scale and reach a lower position than those on the south side of hills. The third step of cirques and the lateral moraines near hillslope which have a weathered layer in their surfaces represent earlier stage of Pleistocene glaciation. The other steps of cirques and other lateral moraines represent later stage of Pleistocene glaciation. The gavels in the tills all came from the bedrocks in the glaciation area and their frabrics are not well-developed. The tills contain more sand and less silt. On the curves of grainsize distribution, main peaks occur in 0-1(?) and the second peaks occur in 2-3(?). There are typical surface textures on the glacial quatz sands, such as compressed pits , striations and 'steps' . Leaching of silicon and the accumulation of iron and aluminium are not obvious and illite is the main clay mineral.