Antarctic Subglacial Aquatic Environments
Antarctic Subglacial Aquatic Environments
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南极冰下水生环境
DOI：
10.1029/2010gm000940
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
Bentley M
中科院分区：
文献类型：
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作者：
Bentley M
资助的南极大陆冰下深湖钻探计划的发展意味着，从地球最大冰盖下孤立和未开发的水生环境中恢复第一批沉积物的前景迫在眉睫。在这里，我们展示了这些沉积物是如何在过去的冰盖配置，古环境变化，并在深，暗，冷设置冰下湖泊的生命存在的信息的潜在档案。我们回顾什么是已知的冰下湖泊沉积物的物理特性，间接从现代和前冰下湖泊的远程地球物理调查和直接从前冰下湖泊出现在南极冰盖的边缘和其他地方的陆地环境的沉积物取样。我们表明，平均沉积速率在冰下湖泊可以从接近零到每年几毫米，在冰下湖泊沉积序列的厚度范围从几厘米到几百米。控制沉积速率和沉积厚度的最重要因素可能是区域基底水系输送的含沙水量。间歇性湖泊排放也可能对某些沉积层序产生重大影响。我们的审查和以前记录的湖沼学和冰川学过程的基础上，我们提出了一个概念模型的冰下湖泊沉积，我们适用于湖沃斯托克，埃尔斯沃思和Whillans。我们讨论了可能的沉积物的物理特性的影响，设计取芯技术和分析程序的选择，以检查冰下湖泊沉积物样品。
The development of funded programs to drill into deep continental Antarctic subglacial lakes means that there is an imminent prospect of retrieving the first sediments from isolated and unexplored aquatic environments beneath Earth’s largest ice sheet. Here we demonstrate how these sediments are potential archives of information on past ice sheet configurations, paleoenvironmental change, and the presence of life in the deep, dark, and cold setting of subglacial lakes. We review what is known about the physical characteristics of subglacial lake sediments, indirectly from remote geophysical surveys of modern and former subglacial lakes and directly from sampling of sediments in former subglacial lakes emerging at the margin of the Antarctic ice sheet and terrestrial settings elsewhere. We show that mean sedimentation rates in subglacial lakes can vary from near zero to several millimeters per year and that the thickness of sedimentary sequences in subglacial lakes ranges from a few centimeters to several hundred meters. The most important control on sedimentation rate and sediment thickness is likely to be the amount of sediment-laden water delivered by regional basal water systems. Episodic lake discharge will also likely have a significant impact on some sedimentary sequences. On the basis of our review and previously documented limnological and glaciological processes, we propose a conceptual model of subglacial lake sedimentation that we apply to lakes Vostok, Ellsworth, and Whillans. We discuss the implications of the likely sediment physical characteristics for designing coring technologies and for the choice of analytical procedures to examine sediment samples from subglacial lakes.