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TitleRegional stagnation of the western Keewatin ice sheet and the significance of meltwater corridors and eskers, northern Canada
 
AuthorSharpe, D R; Lesemann, J -E; Knight, R DORCID logo; Kjarsgaard, B AORCID logo
SourceCanadian Journal of Earth Sciences vol. 58, issue 10, 2021 p. 1-22, https://doi.org/10.1139/cjes-2020-0136 Open Access logo Open Access
Image
Year2021
Alt SeriesNatural Resources Canada, Contribution Series 20200745
PublisherCanadian Science Publishing
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf; html
ProvinceNunavut
NTS65L; 65M; 66D; 75I; 75J; 75K; 75L; 75M; 75N; 75O; 75P; 76A; 76B; 76C; 76D
AreaSnap Lake; Great Slave Lake; Dubawnt Lake; Lac de Gras
Lat/Long WENS-112.0000 -102.0000 65.0000 62.0000
Subjectssurficial geology/geomorphology; geophysics; Nature and Environment; Science and Technology; glacial history; glaciation; deglaciation; ice flow; glacial erosion; depositional history; glacial deposits; tills; glacial landforms; glacial features; eskers; meltwater channels; drumlins; glacial scours; lag deposits; boulders; moraines; ice margins; ice retreat; paleodrainage; clasts; provenance; ice thickness; models; remote sensing; satellite imagery; Laurentide Ice Sheet; Keewatin Sector; East Arm Flow Tract; Keewatin Ice Divide; McAlpine Moraine; Chantrey Moraine; ArcticDEM; subglacial meltwater corridors; glaciofluvial terraced sediments; Digital elevation data
Illustrationsgeoscientific sketch maps; photographs; satellite images; digital elevation models; schematic models; schematic cross-sections; block diagrams; schematic representations
ProgramGEM2: Geo-mapping for Energy and Minerals GEM Synthesis
Released2021 04 07
AbstractThe 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 (~100-200 km), relatively wide (~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.
Summary(Plain Language Summary, not published)
Glacial landscape of western Keewatin region, northern Canada are primarily erosional rather than depositional landscapes. Scoured surfaces and a network of long meltwater corridors indicate extensive meltwater floods that removed sediment from the landscape. Despite considerable sediment erosion along long meltwater corridors, moraines and ice-marginal deposits are rare on the Keewatin landscape. Hence, step-wise retreat and dated deglaciation margins require revision. It is proposed that deglaciation of the Keewatin Sector of the Laurentide Ice Sheet was likely controlled by regional stagnation (melt down). These findings raise fundamental questions about how ice sheets melted, and how they are represented within numerical ice sheet models, and, how mineral exploration may be affected.
GEOSCAN ID328104

 
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