Borehole measurements indicate hard bed conditions, Kangerlussuaq sector, western Greenland Ice Sheet
Borehole measurements indicate hard bed conditions, Kangerlussuaq sector, western Greenland Ice Sheet
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钻孔测量表明格陵兰冰盖西部康克鲁斯瓦克区的硬床条件
DOI：
10.1002/2017jf004201
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
U. H. Fischer
中科院分区：
文献类型：
--
作者：
J. Harper;N. Humphrey;T. Meierbachtol;J. Graly;U. H. Fischer
格陵兰冰盖的水文过程和滑动动力学与其河床的结构框架密切相关。因此，确定冰块是否位于相对没有岩石碎片的基岩上，厚的可变形的冰碛层，或一些中间组合，是理解冰盖对融水输入变化的反应的关键。在这里，我们报告直接观测的冰床界面沿着流线样带在西格陵兰冰盖消融区。我们的测量结果来自32个钻孔的网络，这些钻孔从冰缘附近的100米深到830米深，从终点上升46公里。我们在孔中进行了一系列实验和采样技术来调查床层条件。与格陵兰岛其他地方以前的地球物理和钻探研究表明，冰位于厚厚的沉积物层上相反，我们没有发现在Kangerlussuaq冰盖部分的床上有厚厚的沉积物覆盖的证据。我们的观察意味着，这一地区有一个相对干净和坚硬的床，这有利于由冰/基岩相互作用的基础液压系统。河床上缺乏沉积物覆盖可能是由于最近的冰川消退和冰盖这一部分的前进和/或侵蚀的变化速度和沉积物优先通过基岩槽。
The hydrological processes and sliding dynamics of the Greenland Ice Sheet are closely linked to the structural framework of its bed. Establishing whether the ice mass rests on bedrock relatively clear of rock debris, a thick deformable till layer, or some intermediate combination, is therefore key to understanding the ice sheet response to changes in meltwater inputs. Here we report on direct observations of the ice‐bed interface along a flow line transect in the ablation zone of the western Greenland Ice Sheet. Our measurements are derived from a network of 32 boreholes that vary from ~100 m deep near the ice margin to 830 m deep, 46 km upflow from the terminus. We performed a suite of experiments and sampling techniques in the holes to investigate the bed conditions. In contrast to previous geophysical and drilling studies elsewhere in Greenland which have suggested that the ice rests on a thick layer of sediment, we find no evidence for a thick sediment cover on the bed of the Kangerlussuaq sector of the ice sheet. Our observations imply that this area has a relatively clean and hard bed and that this facilitates a basal hydraulic system governed by ice/bedrock interactions. The lack of sediment cover on the bed could be due to recent deglaciation and advance of this sector of the ice sheet and/or variable rates of erosion and preferential routing of sediment through bedrock troughs.
影响因子：
18.3
作者：
Doyle, Samuel H.;Hubbard, Alun;Hubbard, Bryn
通讯作者：
Hubbard, Bryn