Scale independence of till rheology
Scale independence of till rheology
复制标题
耕作流变学的规模独立性
作者：
S. Tulaczyk
摘要 到目前为止，可变形沉积物上的冰运动的冰川学模型中的冰碛流变学的表示主要集中在两种端元情况：（1）线性或轻度非线性的粘性流变学和（2）（接近）塑性流变学。大多数实验室和现场实验支持后一种模型。 Hindmarsh (1997) 和 Fowler (2002, 2003) 提出，实验结果代表了小冰块样本的行为（特征长度尺度约为 0.1 至 1 m），但冰块在长度尺度上表现出粘性，这与确定冰川和冰盖中的冰流速（~1 km 或更长）相关。对西南极洲惠兰斯冰流冰原上短暂加速事件的观测，提供了一个机会，将这个整合超过约 10-100 公里的耕地的原位流变学与在小型实验室样本和当地钻孔实验中确定的同一冰流下方的耕地的流变学进行比较。这一比较表明，惠兰斯冰流下方冰下碛物的流变性与规模无关。
Abstract Representation of till rheology in glaciological models of ice motion over deformable sediments has, until now, focused largely on two end-member cases: (1) linear, or mildly non-linear, viscous rheology and (2) (nearly) plastic rheology. Most laboratory and in situ experiments support the latter model. Hindmarsh (1997) and Fowler (2002, 2003) proposed that experimental results represent the behavior of small till samples (characteristic length scales of ~0.1 to ~1 m) but that till behaves viscously over length scales that are relevant to determination of ice-flow rates in glaciers and ice sheets (~1 km or more). Observations of short speed-up events on the ice plain of Whillans Ice Stream, West Antarctica, provide an opportunity to compare the in situ rheology of this till, integrated over ~10–100 km, with the rheology of till from beneath the same ice stream determined on small laboratory samples and in local borehole experiments. This comparison indicates that the rheology of the subglacial till beneath Whillans Ice Stream is independent of scale.