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TitleA GIS-based multi-proxy analysis of the evolution of subglacial dynamics in the Quebec-Labrador ice dome, northeastern Quebec, Canada
AuthorRice, J MORCID logo; Ross, MORCID logo; Paulen, R CORCID logo; Kelley, S E; Briner, J P
SourceEarth Surface Processes and Landforms 2020 p. 1-23, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20190357
Mediapaper; on-line; digital
File formatpdf; html
NTS23P/13; 23P/14; 23P/15; 23P/16
Lat/Long WENS -66.0000 -64.0000 56.0000 55.5000
Subjectssurficial geology/geomorphology; geochemistry; geophysics; Science and Technology; Nature and Environment; glacial history; glaciation; ice flow; ice sheets; modelling; glacial landforms; glacial deposits; tills; glacial features; glacial scours; glacial erosion; lakes; paleoenvironment; alteration; beryllium geochemistry; weathering; remote sensing; satellite imagery; geophysical interpretations; magnetic interpretations; bedrock geology; Laurentide Ice Sheet; Quebec-Labrador Ice Dome; till blanket; ice-flow directions; Geographic information systems; Geographic data; Classification; Phanerozoic; Cenozoic; Quaternary
Illustrationslocation maps; geoscientific sketch maps; digital elevation models; satellite images; photographs; flow diagrams; histograms; plots; tables
ProgramGEM2: Geo-mapping for Energy and Minerals Hudson/Ungava, Northeastern Quebec-Labrador, surficial geology
Released2020 07 17
AbstractThe glacial records of the inner-core regions of the Laurentide Ice Sheet (LIS) document complex, yet coherent patterns reflecting ice sheet change (e.g., ice-divide migration) providing unique insights into past glacial conditions. This study develops a conceptual model of subglacial dynamics evolution within a major ice-dispersal centre of the LIS in northeastern Quebec, Canada using a GIS-based analysis of the surficial geologic record. Multiple proxies of subglacial conditions (subglacial streamlined landforms, lake density and lake area over thin drift/bedrock), were analyzed through grid-overlay techniques and then classified based on different proxy variables ranging from highly mobile warm-based to immobile cold-based conditions. An additional proxy (till blanket) was used to identify areas of thick till deposition but with few proxies (few lake or landform metrics). Based on local ice-flow reconstructions, the most ‘relict’ glacial terrain zone (GTZ1) has warm-based conditions over 66% of its area and is remarkably well-preserved, suggesting laterally extensive warm-based conditions during the oldest identified ice-flow phase. This relict glacial terrain is partially overprinted by two subsequent ice-flow phases in spatially restricted zones in the northeast (73% warm-based), east-central (41% warm-based), and northwest (33% warm-based) of the study area. A zone of more sluggish conditions (only 3% warm-based) was identified in the highlands at the centre of the study area, characterized by thin till cover, few landforms, yet with large patches of relatively abundant small lakes, indicative of areal scouring. No clear evidence of sustained cold-based conditions (i.e., high chemical index of alteration values or high 10Be abundances) were found in the study area. These results suggest warm-based conditions (active erosion and/or deposition) were uniformly widespread during the earliest ice-flow phase, later becoming more spatially restricted with broader sluggish ice conditions. These spatially restricted regions of warm-based subglacial regimes were likely controlled by surrounding and down-flow ice streaming.
Summary(Plain Language Summary, not published)
A landscape analysis undertaken over a former ice-divide region, to examine glacial weather vigour, done as part of a PhD research project

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