关于山谷冰川冰-岩界面地貌过程与冰川动力耦合模式——以中天山冰川为例

An Observation and Discussion on the Physical Processes at Ice-Rock Interface

对冰川侵蚀形态的观测与分析得知：（１）冰川槽谷中冰川擦痕的大小和密度在中心较大，鲸背岩出现在冰川槽谷的中部，羊背石发育在槽谷两侧。因此，可以将槽谷分为强烈磨蚀的中部和弱磨蚀而强拔蚀的两侧。（２）冰坎的纵剖面上，迎冰面可见鲸背岩、羊背石以及倾角２０°的剪切裂隙；背冰面以拔蚀为主，见倾角４０°的张性裂隙。沿冰川槽谷纵向，剪切裂隙出现在压缩部位，张裂隙出现在伸张部位。它反映出冷底冰川的动力特性与冰床基岩的受力机制的一致性。

It was found that: (1) Striae are larger and more closely spaced at the centers of U-shaped valleys, but decrease towards the sides. Whale backs occur near the middle of U-shaped valleys, whereas roches moutonnees are found along the valley sides. Thus a U-shaped valley can be divided into a highly abraded center part and weakly abraded but highly quarried side parts. (2) On the longtitudinal section of cross-walls, there are roches moutonnees, whale backs, and highly abraded shear fissures with an angle below 20° on the stoss side . On the lee side, extension fissures with an angle larger than 40° to the horizontal surface appear. Along a U-shaped valley longtitudinal shear fissures appear on the compression sites and extension fissures appear on the tension site. This phenomenon reflects the fact that the glacier and the bed have very uniform mechanical properties. That is to say, where the glacier forms shear faces, shear fissures appear on the underlying bed. and when the glacier forms extension faces, tension fissures appear on the underlying bed and when the glacier forms extension faces, tension fissures appear on the bed. This obviously shows that cold-based glaciers have unique movement characteristics which are not possessed by the other transporting agents, because the freezing-based glacier may tend to merge into an organic whole with the underlying bed.