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Regional stagnation of the western Keewatin ice sheet and the significance of meltwater corridors and eskers, northern Canada
被引:9
|作者:
Sharpe, D. R.
[1
]
Lesemann, J-E
[2
]
Knight, R. D.
[1
]
Kjarsgaard, B. A.
[1
]
机构:
[1] Geol Survey Canada, 601 Booth St, Ottawa, ON K1A 0E8, Canada
[2] Vancouver Isl Univ, Dept Earth Sci, 900 Fifth St, Nanaimo, BC, Canada
关键词:
meltwater corridors;
eskers;
deglacial processes;
regional stagnation;
Keewatin;
Laurentide Ice Sheet;
SOUTH-CENTRAL ONTARIO;
TUNNEL VALLEYS;
SUBGLACIAL DRAINAGE;
GLACIAL GEOMORPHOLOGY;
HUMMOCK CORRIDORS;
OUTBURST FLOODS;
LAKE;
SEDIMENT;
SECTOR;
FLOW;
D O I:
10.1139/cjes-2020-0136
中图分类号:
P [天文学、地球科学];
学科分类号:
07 ;
摘要:
The glacial land system of western Keewatin region, northern Canada, consists of three significant events: (1) regional emplacement of subglacial sediments, mainly till; (2) landscape erosion with development of an integrated, anabranched network of meltwater drainage routes leading to meltwater corridors; and (3) deposition of an extensive array of eskers, and related landforms, within meltwater corridors. Integration of extensive field observations, mapping, and remotely sensed data allow us to link scoured bedrock and till surfaces, truncated drumlins, scour pits, glaciofluvial terraces, boulder lags, and a large-scale network of corridors, as part of regional meltwater erosion events. The network of long (similar to 100-200 km), relatively wide (similar to 1-3 km) meltwater corridors record confined subglacial erosion that scoured sediment (and bedrock) prior to glaciofluvial sedimentation (predominately eskers). Despite considerable sediment erosion along meltwater corridors, moraines and other ice-marginal deposits are rarely observed on the western Keewatin landscape. The absence of these features is inconsistent with deglacial models relying on step-wise active retreat of the ice margin. Instead, we propose that deglaciation of the western Keewatin sector of the Laurentide Ice Sheet was predominantly controlled by regional thinning and stagnation. These findings raise fundamental questions about deglacial patterns and processes and thus suggest that further evaluation and revision of existing models of deglacial chronology for this sector of the Laurentide Ice Sheet is needed.
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页码:1005 / 1026
页数:22
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