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Near-constant retreat rate of a terrestrial margin of the Laurentide Ice Sheet during the last deglaciation
Geology ( IF 5.8 ) Pub Date : 2021-12-01 , DOI: 10.1130/g49081.1
Thomas V. Lowell 1 , Meredith A. Kelly 2 , Jennifer A. Howley 2 , Timothy G. Fisher 3 , Peter J. Barnett 4 , Roseanne Schwartz 5 , Susan R.H. Zimmerman 6 , Nathaniel Norris 1 , Andrew G.O. Malone 7
Affiliation  

The Laurentide Ice Sheet (LIS) was the largest ice sheet during the last glacial period. An accurate representation of its behavior during the last deglaciation is critical to understanding its influence on and response to a changing climate. We use 10Be dating and Bayesian modeling to track the recession of the southwest sector of the Labrador Dome of the LIS along an ∼500-km-long transect west of Lake Superior during the last deglaciation. This transect reflects terrestrial ice-margin retreat and crosses multiple moraine sets, with the southwestern part of the transect deglaciated by ca. 19 ka and the northeastern part deglaciated by ca. 10 ka. The predominant behavior of the ice margin during this interval is near-constant retreat with retreat rates varying between ∼59 m/a and 38 m/a. The moraine sets mark standstills and/or readvances that in total constitute only ∼17% of the retreat interval. The spatial and temporal pattern of ice-margin retreat tracked here differs from existing reconstructions that are based on using isochrons to define ice-margin positions. Acknowledging the uncertainties associated with the modeled ages of ice-margin retreat, we suggest that the overall retreat pattern is consistent with forcing by a gradual increase in Northern Hemisphere, high-latitude summer insolation. The pattern of ice-margin retreat is inconsistent with Greenland ice-core temperature records, and thus these records may not be suitable to drive models of the LIS.

中文翻译:

最后一次冰消期间劳伦泰德冰盖陆地边缘近乎恒定的退缩率

劳伦泰德冰盖 (LIS) 是末次冰期最大的冰盖。在最后一次冰消期期间准确描述其行为对于了解其对气候变化的影响和响应至关重要。我们使用 10Be 定年法和贝叶斯模型来跟踪上次冰消期间沿苏必利尔湖以西约 500 公里长的横断面的 LIS 拉布拉多圆顶西南部分的衰退。该断面反映了陆地冰缘退缩并穿过多个冰碛组,断面的西南部冰川消融约 19 ka 和东北部冰川消融约。10 卡。在此间隔期间,冰缘的主要行为是近乎恒定的后退,后退率在~59 m/a 和 38 m/a 之间变化。冰碛设置标志着静止和/或重新前进,总共仅占撤退间隔的 17%。这里跟踪的冰缘退缩的空间和时间模式不同于现有的基于使用等时线来定义冰缘位置的重建。承认与模拟的冰缘退缩年龄相关的不确定性,我们认为整体退缩模式与北半球高纬度夏季日照逐渐增加的强迫一致。冰缘退缩模式与格陵兰冰芯温度记录不一致,因此这些记录可能不适合驱动LIS模型。这里跟踪的冰缘退缩的空间和时间模式不同于现有的基于使用等时线来定义冰缘位置的重建。承认与模拟的冰缘退缩年龄相关的不确定性,我们认为整体退缩模式与北半球高纬度夏季日照逐渐增加的强迫一致。冰缘退缩模式与格陵兰冰芯温度记录不一致,因此这些记录可能不适合驱动LIS模型。这里跟踪的冰缘退缩的空间和时间模式不同于现有的基于使用等时线来定义冰缘位置的重建。承认与模拟的冰缘退缩年龄相关的不确定性,我们认为整体退缩模式与北半球高纬度夏季日照逐渐增加的强迫一致。冰缘退缩模式与格陵兰冰芯温度记录不一致,因此这些记录可能不适合驱动LIS模型。高纬度夏季日晒。冰缘退缩模式与格陵兰冰芯温度记录不一致,因此这些记录可能不适合驱动LIS模型。高纬度夏季日晒。冰缘退缩模式与格陵兰冰芯温度记录不一致,因此这些记录可能不适合驱动LIS模型。
更新日期:2021-11-23
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