Ice sheet-derived submarine groundwater discharge on Greenland's continental shelf
Ice sheet-derived submarine groundwater discharge on Greenland's continental shelf
复制标题
DOI：
10.1029/2011wr010536
复制
发表时间：
2011-07-28
影响因子：
5.4
通讯作者：
Dugan, Brandon
中科院分区：
文献类型：
--
作者：
DeFoor, Whitney;Person, Mark;Dugan, Brandon
在格陵兰东南部近海100公里的大陆架沉积物中发现了同位素轻（-1%至-8%三角洲O-18）和新鲜孔隙流体（300-520 mM Cl-），表明冰盖融水与海水的渗透和混合深度为260 m。这些地球化学异常可能与冰盖派生的海底地下水排放（SMGD）。我们提出了一个大陆规模的重建晚更新世的格陵兰东南部的水文地质有限元分析，结合冰盖负荷和溶质和同位素输运。结果表明，冰下渗透和SMGD是同一数量级，并高度依赖于陆上玄武岩的渗透性。模拟渗透和SMGD几乎翻了一番，在末次盛冰期，相比无冰条件。现今冰川引起的地下水排放大部分发生在陆地上。大陆架上的冰下渗透可能代表了过去最大冰期期间海水和融水的混合物。模拟SMGD在最近的间隔冰川退缩约4%的总冰盖融化。目前，SMGD的模拟速率约为当前估计熔化速率的11%。
Isotopically light (-1% to -8% delta O-18) and fresh pore fluids (300-520 mM Cl-) were found in continental shelf sediments up to 100 km offshore of southeastern (SE) Greenland, suggesting infiltration and mixing of ice sheet meltwater with seawater to depths of 260 m. These geochemical anomalies may be associated with ice sheet-derived submarine groundwater discharge (SMGD). We present a continental-scale reconstruction of the late Pleistocene hydrogeology of SE Greenland using finite element analysis that incorporates ice sheet loading and solute and isotope transport. Results indicate that subglacial infiltration and SMGD are of the same order of magnitude and are highly dependent on the permeability of the subaerial basalt. Simulated infiltration and SMGD almost doubled during the Last Glacial Maximum, compared to ice-free conditions. Much of the present-day glacially induced groundwater discharge occurs on land. Subice infiltration on the continental shelf likely represents a mixture of seawater and meltwater during past glacial maximums. Simulated SMGD during the most recent interval of glacial retreat is about 4% of the total ice sheet melting. At present, the simulated rate of SMGD is about 11% of the estimated current melting rate.