Glacier-Bed Landforms of the Prairie Region of North America
Glacier-Bed Landforms of the Prairie Region of North America
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北美草原地区的冰川床地貌
DOI：
10.1017/s0022143000030161
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发表时间：
1979
影响因子：
3.4
通讯作者：
L. Andriashek
中科院分区：
文献类型：
--
作者：
S. Moran;L. Clayton;R. Hooke;M. M. Fenton;L. Andriashek
摘要 在更新世大陆冰盖床层或附近形成的两种主要地形广泛分布于加拿大和美国的草原地区。这些是（1）冰川逆冲块和源洼地和（2）流线型地形。冰川逆冲地形在冰川被冻结到基底的地方形成，并且升高的孔隙水压力将基底的剪切强度降低到小于冰川所施加的值。冰盖边缘带由冻床带组成，部分宽度不超过2～3公里，其中冰川逆冲块体较大，呈棱角状。从该区域向上的冰川，推力块通常较小且平滑。流线型地形始于已知冰缘位置后方 2 至 3 公里处，并向冰川上方延伸数十公里。流线型地形以两种方式形成：（1）由于次边缘解冻层区域的基底滑动而导致的基底侵蚀；（2）侵蚀平滑，伴随着在冲断块的背风处安置耕耘物，在冲断块沉积并随后暴露于解冻床条件下，这是由于冰川的进一步推进。该论文已被接受在未来一期的《冰川学杂志》上全文发表。
Abstract Two major types of terrain that formed at or near the bed of Pleistocene continental ice sheets are widespread throughout the prairie region of Canada and the United States. These are (1) glacial-thrust blocks and source depressions and (2) streamlined terrain. Glacial-thrust terrain formed where the glacier was frozen to the substrate and where elevated pore-water pressure decreased the shear strength of the substrate to a value less than that applied by the glacier. The marginal zone of ice sheets consisted of a frozen-bed zone, no more than 2 to 3 km wide in places, within which glacial-thrust blocks are large and angular. Up-glacier from this zone the thrust blocks are generally smaller and smoothed. Streamlined terrain begins 2 to 3 km behind known ice-margin positions and extends tens of kilometres up-glacier. Streamlined terrain formed in two ways: (1) erosion of the substrate as a consequence of basal sliding in the sub-marginal thawed-bed zone and (2) erosional smoothing accompanied by emplacement of till in the lee of thrust blocks where they were deposited and subsequently exposed to thawed-bed conditions as a result of further advance of the glacier. This paper has been accepted for publication in full in a future issue of the Journal of Glaciology.