Laboratory Studies of the Physics of Debris Entrainment, Transport, and Deposition at the Bed of a Temperate Glacier

冰川底部的侵蚀、夹带和沉积过程控制着可用于冰下改造的碎屑的供应，因此，在次冰川雕刻地形的演变中发挥着重要作用。此外，冰下碎屑的变形直接影响许多冰川和冰盖的动态。尽管有强烈的动机研究浓缩碎片、冰和冰川床之间的相互作用物理，但还没有在控制良好的现实条件下进行实验室实验。我们提出了一系列实验，在这些实验中，将密切模拟温度冰川床上的条件。在一些实验中，岩层滑到了含有致密岩石颗粒的固定温带冰块下面。我们的目标将是模拟冰川磨损和碎片粉碎，并演示发生底部融化和碎片夹带的条件。到目前为止的实验表明，这些过程强烈地受到冰的渗透趋势的影响，并通过重新融化通过碎石流动。为了更好地理解这一过程，在其他实验中，将通过推动冰穿过三维球体阵列来理想化冰通过冰斗的重新关系。结果将与现有回归理论的预测进行比较，我们将通过包括溶质对温度梯度的重要影响来修正该理论。在这两个系列的实验中，所有相关的冰川变量都将被监测，包括冰层和床面温度、基础融化速度和有效压力。这些实验将填补冰川地质过程研究中的一个明显空白。

Processes of erosion, entrainment, and deposition at the beds of glaciers govern the supply of debris available for subglacial modification, and thus, play an important role in the evolution of subglacially sculpted topography. In addition, deformation of subglacial debris directly influences the dynamics of many glaciers and ice sheets. Despite the strong motivation for studying the physics of interactions between concentrated debris, ice, and glacier beds, no laboratory experiments under well controlled, realistic conditions have been conducted. We propose a series of experiments in which conditions at the bed of a temperature glacier will be closely simulated. In some experiments, a rock bed slid beneath a fixed block of temperate ice that contains dense arrays of rock particles. Our goals will be to simulate glacial abrasion and debris comminution, and to demonstrate the conditions under which basal melt-out and entrainment of debris occur. Experiments to date indicate that these processes are strongly affected by the tendency for ice to penetrate and flow through debris by regelation. To better understand this process regelation of ice through till will be idealized in other experiments by pushing ice through a three-dimensional array of spheres. Results will be compared with predictions of an existing regelation theory, which we will modify by including the important effect of solutes on thermal gradients. In both series of experiments, all pertinent glaciological variables will be monitored, including ice and bed temperature, basal melt rate, and effective pressure. These experiments will held fill a conspicuous void in the study of glacial geologic processes.