Evolution of the Laurentide and Innuitian ice sheets prior to the Last Glacial Maximum (115 ka to 25 ka)
Evolution of the Laurentide and Innuitian ice sheets prior to the Last Glacial Maximum (115 ka to 25 ka)
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DOI：
10.1016/j.earscirev.2021.103875
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发表时间：
2022-01-01
影响因子：
12.1
通讯作者：
Batchelor, Christine L.
中科院分区：
文献类型：
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作者：
Dalton, April S.;Stokes, Chris R.;Batchelor, Christine L.
劳伦蒂德冰盖是上一次冰川周期(-115ka至-10ka)期间增长和衰退的最大的全球冰块。尽管Laurentide(和邻近的Innuitian)冰盖对于推动全球平均海平面、长期地貌演变和大气环流模式的重大变化很重要，但由于在最后一次冰盛期(LGM；-25ka)之前零星保存了地层记录，以及对现有证据采取个案研究方法，其历史受到的限制很小。在这里，我们综合来自冰川区的现有地质年代学数据，连同已公布的地层和地貌数据，以及数值模拟输出，得出19个假设重建的Laurentide和Innutian冰盖，从115 ka到25 ka，间隔5 KYR，不确定性被量化，包括每个时间步的最佳、最小和最大冰范围估计。我们的工作表明，在115ka到25ka之间，北美的一些地区经历了多次冰盖快速增长和衰退的周期，而其他地区基本上保持无冰，其他地区则持续冰川。主要发现包括：(I)从115ka到80ka的Laurentide冰盖的增长和衰退；(Ii)-60ka的冰层显著积聚，几乎达到末次冰盖的程度；(Iii)北美冰层在-45ka可能急剧减少；(Iv)拉布拉多穹顶在-38ka的快速扩张；(V)从-35ka开始向末次冰盖逐渐增长。有些重建只是松散的限制，因此是投机性的(特别是在45ka之前)。然而，根据现有证据，这项工作代表了我们对Laurentide和Innuitian冰盖在最后一次冰川周期到LGM期间形成的最新理解。我们认为这些冰结构是一系列可测试的假设，供未来的工作解决和完善。这些结果对包括冰盖建模、古气候学和考古学在内的一系列学科的使用都很重要，并且可以通过数字方式获得。
The Laurentide Ice Sheet was the largest global ice mass to grow and decay during the last glacial cycle (-115 ka to-10 ka). Despite its importance for driving major changes in global mean sea level, long-term landscape evolution, and atmospheric circulation patterns, the history of the Laurentide (and neighbouring Innuitian) Ice Sheet is poorly constrained owing to sporadic preservation of stratigraphic records prior to the Last Glacial Maximum (LGM;-25 ka) and a case-study approach to the dating of available evidence. Here, we synthesize available geochronological data from the glaciated region, together with published stratigraphic and geomorphological data, as well as numerical modelling output, to derive 19 hypothesised reconstructions of the Laurentide and Innuitian ice sheets from 115 ka to 25 ka at 5-kyr intervals, with uncertainties quantified to include best, minimum, and maximum ice extent estimates at each time-step. Our work suggests that, between 115 ka and 25 ka, some areas of North America experienced multiple cycles of rapid ice sheet growth and decay, while others remained largely ice-free, and others were continuously glaciated. Key findings include: (i) the growth and recession of the Laurentide Ice Sheet from 115 ka through 80 ka; (ii) significant build-up of ice to almost LGM extent at-60 ka; (iii) a potentially dramatic reduction in North American ice at-45 ka; (iv) a rapid expansion of the Labrador Dome at-38 ka; and (v) gradual growth toward the LGM starting at-35 ka. Some reconstructions are only loosely constrained and are therefore speculative (especially prior to 45 ka). Nevertheless, this work represents our most up-to-date understanding of the build-up of the Laurentide and Innuitian ice sheets during the last glacial cycle to the LGM based on the available evidence. We consider these ice configurations as a series of testable hypotheses for future work to address and refine. These results are important for use across a range of disciplines including ice sheet modelling, palaeoclimatology and archaeology and are available digitally.