期刊
GEOPHYSICAL RESEARCH LETTERS
卷 46, 期 12, 页码 6673-6680出版社
AMER GEOPHYSICAL UNION
DOI: 10.1029/2019GL082304
关键词
esker; subglacial landforms; mathematical model; deglaciation
资金
- Marie Curie FP7 Career Integration Grant [PCIG13-GA-2013-618007]
- U.S. Polar Programs Grant [NSF-1643970]
- NASA [NNX16AJ95G]
- Vetlesen Foundation
- NASA [902571, NNX16AJ95G] Funding Source: Federal RePORTER
We develop a mathematical model for esker formation by the continuous deposition of sediments near the mouth of water-filled subglacial tunnels. We assume a retreating ice sheet margin and prescribe meltwater and sediment supply to a channelized subglacial drainage system. The hydrodynamic model for the subglacial channel has its cross section governed by wall melting, creep closure, and sediment deposition. Sediment-carrying capacity typically increases downstream, before decreasing rapidly near the margin, suggesting that most deposition occurs there. This can lead to choking near the margin, which is offset by enhanced melting to keep the channel open. The model shows that the deposition rate varies roughly quadratically with sediment supply and inversely with water flux. For given sediment supply, the model suggests esker formation is most prevalent in smaller channels. Larger ice sheet melt rates likely produce more closely spaced eskers, but with smaller cross sections.
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