Alley R B, Lawson D E, Larson G J, Evenson E B, Baker G S
Department of Geosciences and EMS Environment Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Nature. 2003 Aug 14;424(6950):758-60. doi: 10.1038/nature01839.
Glaciers often erode, transport and deposit sediment much more rapidly than nonglacial environments, with implications for the evolution of glaciated mountain belts and their associated sedimentary basins. But modelling such glacial processes is difficult, partly because stabilizing feedbacks similar to those operating in rivers have not been identified for glacial landscapes. Here we combine new and existing data of glacier morphology and the processes governing glacier evolution from diverse settings to reveal such stabilizing feedbacks. We find that the long profiles of beds of highly erosive glaciers tend towards steady-state angles opposed to and slightly more than 50 per cent steeper than the overlying ice-air surface slopes, and that additional subglacial deepening must be enabled by non-glacial processes. Climatic or glaciological perturbations of the ice-air surface slope can have large transient effects on glaciofluvial sediment flux and apparent glacial erosion rate.
冰川侵蚀、搬运和沉积沉积物的速度通常比非冰川环境快得多，这对冰川山脉带及其相关沉积盆地的演化具有重要意义。但是，对这种冰川过程进行建模很困难，部分原因是尚未在冰川地貌中识别出与河流中运行的类似的稳定反馈机制。在这里，我们结合了来自不同环境的冰川形态新数据和控制冰川演化的过程数据，以揭示这种稳定反馈机制。我们发现，高度侵蚀性冰川的床面纵剖面倾向于达到稳态角度，该角度与上覆冰-气表面坡度相反，且比其陡50%以上，并且额外的冰下加深作用必须由非冰川过程来实现。冰-气表面坡度的气候或冰川学扰动可能会对冰川河流沉积物通量和表观冰川侵蚀速率产生较大的瞬态影响。
