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  • 标题:Recumbent folding of divide arches in response to unsteady ice-divide migration
  • 本地全文:下载
  • 作者:H. Paul Jacobson ; Edwin D. Waddington
  • 期刊名称:Journal of Glaciology
  • 印刷版ISSN:0022-1430
  • 电子版ISSN:1727-5652
  • 出版年度:2005
  • 卷号:51
  • 期号:173
  • 页码:201-209
  • DOI:10.3189/172756505781829412
  • 出版社:Cambridge University Press
  • 摘要:Arches in stratigraphic layers directly under a flow divide (Raymond bumps) are predicted by models of steady ice-sheet flow, and have been observed in several ice domes. Here, we model the evolution of these layers when a formerly stationary divide migrates rapidly to a new position, then again becomes stationary, leaving the arched layers in a flank position. As they are then carried downstream with the flow, these abandoned arches can develop into recumbent folds. These folds can occur over a wide range of divide migration speeds. The shearing flow that produces these recumbent folds also distributes the folded layers over a wide distance downstream from the original divide location. If the divide offset is abrupt, ‘pre-cores’, or material lines comprising core-relative isochrones, can be used to quickly identify portions of an abandoned Raymond bump that would be overturned at any future ice-core site downstream. If, as appears to be the case in Greenland, the divide is never stable long enough to produce a mature arch, folds of this type would not occur. The most likely place to find such folds might be the flank of an ice ridge bounded by unsteady ice streams.
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