Subglacial controls on the flow of Institute Ice Stream, West Antarctica
Subglacial controls on the flow of Institute Ice Stream, West Antarctica
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DOI：
10.1017/aog.2016.17
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发表时间：
2016-05
影响因子：
2.9
通讯作者：
M. Siegert;N. Ross;Jilu Li;D. Schroeder;D. Rippin;D. Ashmore;R. Bingham;P. Gogineni
中科院分区：
文献类型：
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作者：
M. Siegert;N. Ross;Jilu Li;D. Schroeder;D. Rippin;D. Ashmore;R. Bingham;P. Gogineni
摘要 研究所冰流 (IIS) 位于反向倾斜的河床上，向上游延伸超过 150 公里，进入深约 1.8 公里的罗宾冰下盆地，使其处于海洋冰盖不稳定的临界点。了解 IIS 漏洞的重点是接地线熔化的影响，预计该影响将在本世纪显着增加。冰流动力学的变化对于 IIS 的稳定性也很重要，但人们对此知之甚少。在这里，我们揭示了 IIS 的主干出现在三个离散的冰下特征交汇处的下游；一个大型“活跃”冰下湖、新发现的向薄弱基底沉积物区域的急剧过渡以及主要的构造裂谷。 IIS 干流的边界受到一侧沉积物的限制，并受到与邦根斯托克冰隆边界处的基底融化和冻结之间的过渡的限制。通过展示基底沉积物和水如何决定当今的 IIS 流量，我们揭示了这里冰盖的稳定性取决于这种不寻常的排列。
ABSTRACT The Institute Ice Stream (IIS) rests on a reverse-sloping bed, extending >150 km upstream into the ~1.8 km deep Robin Subglacial Basin, placing it at the threshold of marine ice-sheet instability. Understanding IIS vulnerability has focused on the effect of grounding-line melting, which is forecast to increase significantly this century. Changes to ice-flow dynamics are also important to IIS stability, yet little is known about them. Here we reveal that the trunk of the IIS occurs downstream of the intersection of three discrete subglacial features; a large ‘active’ subglacial lake, a newly-discovered sharp transition to a zone of weak basal sediments and a major tectonic rift. The border of IIS trunk flow is confined by the sediment on one side, and by a transition between basal melting and freezing at the border with the Bungenstock Ice Rise. By showing how basal sediment and water dictate present-day flow of IIS, we reveal that ice-sheet stability here is dependent on this unusual arrangement.