气候变化领域集成服务门户(CCPortal): Using a composite flow law to model deformation in the NEEM deep ice core, Greenland-Part 1: The role of grain size and grain size distribution on deformation of the upper 2207 m

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DOI	10.5194/tc-14-2429-2020
	Using a composite flow law to model deformation in the NEEM deep ice core, Greenland-Part 1: The role of grain size and grain size distribution on deformation of the upper 2207 m
	Kuiper E.-J.N.; Weikusat I.; De Bresser J.H.P.; Jansen D.; Pennock G.M.; Drury M.R.
发表日期	2020
ISSN	19940416
起始页码	2429
结束页码	2448
卷号	14 期号:7
英文摘要	The effect of grain size on strain rate of ice in the upper 2207m in the North Greenland Eemian Ice Drilling (NEEM) deep ice core was investigated using a rheological model based on the composite flow law of Goldsby and Kohlstedt (1997, 2001). The grain size was described by both a mean grain size and a grain size distribution, which allowed the strain rate to be calculated using two different model end-members: (i) the microscale constant stress model where each grain deforms by the same stress and (ii) the microscale constant strain rate model where each grain deforms by the same strain rate. The model results predict that grainsize-sensitive flow produces almost all of the deformation in the upper 2207m of the NEEM ice core, while dislocation creep hardly contributes to deformation. The difference in calculated strain rate between the two model end-members is relatively small. The predicted strain rate in the fine-grained Glacial ice (that is, ice deposited during the last Glacial maximum at depths of 1419 to 2207 m) varies strongly within this depth range and, furthermore, is about 4 5 times higher than in the coarser-grained Holocene ice (0 1419 m). Two peaks in strain rate are predicted at about 1980 and 2100m depth. The prediction that grain-size-sensitive creep is the fastest process is inconsistent with the microstructures in the Holocene age ice, indicating that the rate of dislocation creep is underestimated in the model. The occurrence of recrystallization processes in the polar ice that did not occur in the experiments may account for this discrepancy. The prediction of the composite flow law model is consistent with microstructures in the Glacial ice, suggesting that fine-grained layers in the Glacial ice may act as internal preferential sliding zones in the Greenland ice sheet. © 2020 Author(s).
英文关键词	composite; grain size; GRIP; ice core; size distribution
语种	英语
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202132
作者单位	Faculty of Earth Science, Utrecht University, TA Utrecht, 3508, Netherlands; Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, 27570, Germany; Department of Geosciences, Eberhard Karls University Tübingen, Tübingen, 72074, Germany
推荐引用方式 GB/T 7714	Kuiper E.-J.N.,Weikusat I.,De Bresser J.H.P.,et al. Using a composite flow law to model deformation in the NEEM deep ice core, Greenland-Part 1: The role of grain size and grain size distribution on deformation of the upper 2207 m[J],2020,14(7).
APA	Kuiper E.-J.N.,Weikusat I.,De Bresser J.H.P.,Jansen D.,Pennock G.M.,&Drury M.R..(2020).Using a composite flow law to model deformation in the NEEM deep ice core, Greenland-Part 1: The role of grain size and grain size distribution on deformation of the upper 2207 m.Cryosphere,14(7).
MLA	Kuiper E.-J.N.,et al."Using a composite flow law to model deformation in the NEEM deep ice core, Greenland-Part 1: The role of grain size and grain size distribution on deformation of the upper 2207 m".Cryosphere 14.7(2020).