Glacial landforms of extreme size in the Keewatin sector of the Laurentide Ice Sheet
Glacial landforms of extreme size in the Keewatin sector of the Laurentide Ice Sheet
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劳伦泰冰盖基瓦廷区的巨大冰川地貌
DOI：
10.1016/j.quascirev.2010.04.010
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发表时间：
2010
影响因子：
4
通讯作者：
J. Kleman
中科院分区：
文献类型：
--
作者：
S. Greenwood;J. Kleman
这里确定了Laurentide冰盖Keewatin区的“巨型”冰川地貌组合。大直到“带”或“脊”，明显只有在卫星图像和下面的鼓，凹槽和肋冰碛，包括已知的区域冰川地貌记录，形成广泛的和连贯的模式，整个Keewatin地区。根据遥感图像绘制的地形图和山脊线图可绘制出超过2，500种不同地形的总体图，这些地形的平均长度为100公里，宽度为1.5公里。通过对它们的形态学和形态计量学特征、空间排列和格局的分析，并与冰川地貌类型的类似物和参考种群进行比较，我们解释了三个不同成因的形态群。其中两个是目前已知的地貌类型的例子：i）一组严重叠印，即非原始的，大规模的冰川线理，从Keewatin地区的心脏向北流入毛德皇后湾; ii）一个350公里长的冰碛带，被后来的冰流路径所覆盖，可能与最后一次冰消期之前冰盖的终端位置有关。第三组，包括大量的Keewatin人口，不适合任何现有的冰川地貌类别。在这里，我们报告了一个重大的新发现：冰川下的底形，一个超大规模的，横向于古冰流方向。大规模的横向底形以前没有任何古（或当代）冰盖的报道。在Keewatin的肋状冰碛人口密切的空间整合表明了类似的成因模式。Keewatin地貌表明，有一个基本的横向组织，直到在一个规模超出了传统的横向底形（棱状冰碛），并与尚未未知的影响，我们了解冰下过程和冰床耦合。
Assemblages of glacial landforms of a ‘mega-scale’ are here identified in the Keewatin sector of the Laurentide Ice Sheet. Large till ‘belts’ or ‘ridges’, apparent only on satellite imagery and lying beneath the drumlins, flutes and ribbed moraine which comprise the known regional glacial landform record, form extensive and coherent patterns throughout the Keewatin region. Planform and crestline mapping from remotely sensed imagery yields a mapped population of >2500 individual landforms, whose dimensions are on average ∼10 km long and ∼1.5 km wide. Based on analysis of their morphology and morphometry, their spatial arrangement and pattern, and comparison with analogues and reference populations of glacial landform types, we interpret three morphological groups of different genetic origin. Two of these are examples of currently known landform types: i) a set of heavily overprinted, i.e. non-pristine, mega-scale glacial lineations, feeding from the heart of the Keewatin region north into Queen Maud Gulf; and ii) a 350 km long moraine zone, overrun by later ice flow paths, and likely associated with the terminal position of an ice sheet prior to the final deglacial episode. A third group, comprising a significant number of the Keewatin population, does not fit any existing category of glacial landforms. Here we report a major new finding: subglacial bedforms, of a mega-scale, transverse to the palaeo-ice flow direction. Mega-scale transverse bedforms have not been previously reported from any palaeo-(or contemporary) ice sheet. Close spatial integration with the ribbed moraine population in Keewatin suggests a similar mode of genesis. The Keewatin landforms indicate there is a fundamental transverse organisation of till at a scale beyond that of conventional transverse bedforms (ribbed moraine), and with as yet unknown implications for our understanding of subglacial processes and ice-bed coupling.
影响因子：
4
作者：
Clark, Chris D.;Hughes, Anna L. C.;Ng, Felix S. L.
通讯作者：
Ng, Felix S. L.