Modelling North American palaeo-subglacial lakes and their meltwater drainage pathways
Modelling North American palaeo-subglacial lakes and their meltwater drainage pathways
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模拟北美古冰下湖泊及其融水排水路径
DOI：
10.1016/j.epsl.2013.04.017
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发表时间：
2013
影响因子：
5.3
通讯作者：
Livingstone S
中科院分区：
文献类型：
--
作者：
Livingstone S
本文对上一次冰期北美冰盖下的古冰下湖泊及其排泄途径进行了预测。我们利用当前地形和海底测深的数据，以及来自数据校准的冰川模型的冰面和地面地形的高程模型来计算冰盖床的水力势面。考虑到具体的冰面海拔高度只能从模型输出中得知，因此包含很大的不确定性，我们利用许多这样的输出来检查冰层下湖泊可能出现在海床上的什么地方。我们的分析证明了冰下湖泊形成的可能性，特别是在前科迪勒兰冰盖之下；沿劳伦蒂德冰盖和科迪勒兰冰盖之间的缝合带；在哈德逊湾；在加拿大群岛的大湖盆地和深海沟。在最后一次冰川盛期，我们认为至少有1000平方公里的融水可能储存在冰川以下。随着冰盖和冰床的演变，冰下湖泊反复形成和排空，特别是在哈德逊湾和劳伦蒂河和科迪勒兰冰盖之间的缝合带，那里的湖泊以宽而浅(<；10米深)为特点。相比之下，科迪勒兰冰盖的特点是深度(高达∼90米)和持久的湖泊成因。值得注意的是，无论模型或模型运行如何，预测的冰下湖泊的分布和模式都是相似的，这表明结果是稳健的。冰川下融水排水有两种，一种是稳定的网络，通常与强大的地形控制有关，另一种是经历了相当大的活力的错综复杂的网络，包括反复捕获融水网络。这些湖泊可能性预测可以有效地形成详细的实地和远程调查的目标，我们假设和探索许多以前被解释为来自冰缘湖泊的沉积物和溢洪道可能来自它们的冰下表亲。
This paper presents predictions of palaeo-subglacial lakes and their drainage pathways beneath the North American Ice Sheet during the last glaciation. We utilise data on the current topography and seafloor bathymetry, and elevation models of the ice- and ground-surface topography from data-calibrated glaciological modelling to calculate the hydraulic potential surface at the ice-sheets bed. Given that specific ice-surface elevations are only known from modelled outputs, and thus contain significant uncertainty, we utilise many such outputs to examine where on the bed that subglacial lakes are likely to have occurred. Our analysis demonstrates the potential for subglacial lake genesis, particularly beneath the former Cordilleran Ice Sheet; along the suture zone between the Laurentide and Cordilleran ice sheets; in Hudson Bay; in the Great Lake basins and deep trenches of the Canadian Archipelago. During the Last Glacial Maximum we suggest that at least 1000 km3of meltwater could have been stored subglacially. As the ice-sheet and the bed evolved subglacial lakes repeatedly formed and emptied, particularly in Hudson Bay and the suture zone between the Laurentide and Cordilleran ice sheets where lakes were characteristically broad and shallow (<10 m deep). In contrast, the Cordilleran Ice Sheet was characterised by deep (up to ∼90 m) and persistent lake genesis. Significantly, similar distributions and modes of predicted subglacial lakes are obtained irrespective of the model or model run, which suggests the results are robust. Subglacial meltwater drainage varied between stable networks, typically associated with strong topographic controls, and convoluted networks that underwent considerable dynamism, including repeated meltwater network capture. These lake likelihood predictions could usefully form targets for detailed field and remote investigations and we hypothesise and explore the potential that numerous deposits and spillways previously interpreted as arising from ice-marginal lakes may have emanated from their subglacial cousins.
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