Patterns of ice recession and ice stream activity for the MIS 2 Laurentide Ice Sheet in Manitoba, Canada

IF 2.4 3区 地球科学 Q2 GEOGRAPHY, PHYSICAL
Boreas Pub Date : 2021-12-02 DOI:10.1111/bor.12571
Michelle S. Gauthier, Andy Breckenridge, Tyler J. Hodder
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引用次数: 4

Abstract

Reconstruction of deglacial ice margins provides insights into the demise of past ice sheets and ice-marginal lakes and helps to understand how former ice sheets responded to climate change. Here, we reconstruct deglacial Laurentide Ice Sheet margins across Manitoba (Canada), a dynamic region that in MIS 2 spanned from an inner core region of the Keewatin dome to the periphery of the ice sheet (~900 km north of the Last Glacial Maximum limit). The area was also overrun by ice flowing from both the Quebec-Labrador dome and the Hudson Bay Ice Saddle. The surficial landscape of Manitoba contains inherited relict and palimpsest glacial landscapes, which need to be separated from deglacial features. Ice-impounded glacial Lake Hind was present in southwest Manitoba at 13.0 cal. ka BP, meaning most of Manitoba was covered by ice at the start of the Younger Dryas. Northwest drainage of glacial Lake Agassiz in front of the Highrock Lake–Cree Lake moraine could have occurred near the end of the Younger Dryas, prior to 11.5 cal. ka BP, though the volume of the lake varies greatly depending on ice-margin reconstructions. Our interpretation is incompatible with the hypothesis that Lake Agassiz drainage to the Arctic Ocean triggered the Younger Dryas climatic cooling. Numerous ice streams developed across central and southern Manitoba during deglaciation, including the Souris, Red River, The Pas, Hayes and Quinn Lake. The dominant ice source was from the north early in deglaciation, switching to the northeast with growth of the Hudson Bay Ice Saddle and then back to the north again with demise of the saddle. The ice-margin ages are largely unconstrained, and thus we are unable to accurately assign climatic drivers to various ice stream events. Nonetheless, we record the development and demise of terrestrial ice streams over both hard-bed and soft-bed substrates.

Abstract Image

加拿大马尼托巴省MIS 2 Laurentide冰盖冰退缩和冰流活动模式
对冰原边缘的重建提供了对过去冰盖和冰边缘湖泊消亡的见解,并有助于了解以前的冰盖如何应对气候变化。在这里,我们重建了横跨加拿大马尼托巴省(Manitoba)的Laurentide冰原边缘,这是一个动态区域,在MIS 2中从Keewatin圆顶的内心区跨越到冰原的外围(末次冰期极大期以北约900公里)。该地区也被来自魁北克-拉布拉多圆顶和哈德逊湾冰鞍的冰所淹没。曼尼托巴的地表景观包含了继承下来的遗迹和重写的冰川景观,这些景观需要与冰川特征分开。在曼尼托巴西南部,因德湖冰川被冰冻结,温度为13.0卡。这意味着曼尼托巴省的大部分地区在新仙女木期开始时被冰覆盖。海洛克湖-克里湖冰碛前的冰川湖阿加西斯的西北排水可能发生在新仙女木期末期,也就是11.5 cal之前。尽管湖泊的体积因冰缘重建而变化很大。我们的解释与阿加西湖向北冰洋的排水引发新仙女木期气候变冷的假设不相容。在冰川消融期间,马尼托巴中部和南部形成了许多冰流,包括苏里斯河、红河、帕斯河、海耶斯湖和奎因湖。在消冰期早期,主要的冰源来自北方,随着哈德逊湾冰鞍的生长而转向东北,然后随着冰鞍的消失而再次回到北方。冰缘年龄在很大程度上是不受约束的,因此我们无法准确地将气候驱动因素分配给各种冰流事件。尽管如此,我们记录了陆地冰流在硬床和软床上的发展和消亡。
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来源期刊
Boreas
Boreas 地学-地球科学综合
CiteScore
5.90
自引率
4.50%
发文量
36
审稿时长
>12 weeks
期刊介绍: Boreas has been published since 1972. Articles of wide international interest from all branches of Quaternary research are published. Biological as well as non-biological aspects of the Quaternary environment, in both glaciated and non-glaciated areas, are dealt with: Climate, shore displacement, glacial features, landforms, sediments, organisms and their habitat, and stratigraphical and chronological relationships. Anticipated international interest, at least within a continent or a considerable part of it, is a main criterion for the acceptance of papers. Besides articles, short items like discussion contributions and book reviews are published.
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