| Titre | Significance of glacial landsystems and process-form regimes in permafrost terrain: the Smoking Hills region of northwestern Arctic Canada |
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| Auteur | Smith, R ; Evans,
D; Gosse, J |
| Source | INQUA 2019: 20th Congress of the International Union for Quaternary Research, programme; O-5047, 2019 p. 1  Accès ouvert |
| Liens | Online - En ligne
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| Image |  |
| Année | 2019 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20180353 |
| Éditeur | International Union for Quaternary Research |
| Réunion | INQUA 2019: 20th Congress of the International Union for Quaternary Research; Dublin; IE; juillet 25-31, 2019 |
| Document | site Web |
| Lang. | anglais |
| Media | en ligne; numérique |
| Formats | html; pdf |
| SNRC | 97B; 97C |
| Région | Smoking Hills; Horton River |
| Lat/Long OENS | -128.0000 -126.0000 69.5000 68.5000 |
| Sujets | pergélisol; glace fossile; antecedents glaciaires; déformation; glissements de terrain; glissements; dépôts glaciaires; tills; topographie glaciaire; géologie des dépôts meubles/géomorphologie;
stratigraphie; Nature et environnement; Sciences et technologie; Phanérozoïque; Cénozoïque; Quaternaire |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Bassin de Sverdrup de l'ouest de l'Arctique |
| Diffusé | 2019 07 01 |
| Résumé | (disponible en anglais seulement)
In northern Canada, considerations of natural resource potential include not simply identification of a resource itself, but also an understanding of aspects of
engineering geology of surficial and shallow bedrock materials within formerly glaciated terrain, particularly in areas of ice-rich permafrost. Hence, understanding the landscape is not simply a surficial geology mapping exercise, but more an
integrated consideration of the evolution of the landsystem and the inherent process-form regimes. As part of the Geological Survey of Canada's GEM2 research program, this study examined the Smoking Hills region of northwestern Arctic Canada (~69°N;
127°W). While parts of this area were previously reported as unglaciated during the last (Late Wisconsinan) glaciation, new glaciological models and field studies argue that the entire region was glaciated, and that the study area was situated south
of the westward-flowing Amundsen Gulf Ice Stream. A unique older glacial stratigraphy (3-5 separate glaciations) is preserved in the region, for which an improved chronology based on cosmogenic nuclide burial dating and a stratigraphic
reinterpretation is being undertaken.
Regionally exposed bedrock and complex Quaternary stratigraphies located in incised valleys document a range of past glacial processes, and in particular extensive glaciotectonic deformation and entrainment of
poor to weakly-consolidated Cretaceous sedimentary bedrock. Glaciotectonic features include deformed intraclasts of coherent bedrock ranging from thin (<1 cm) stringers and blocks to large metre-scale boudins, cohesive bedrock rafts (metres to 10s of
metres thick) and acute to overturned fold structures ?100 m in vertical height. Extensive preglacial bedrock slumping along valleys likely contributed much of the entrained bedrock material, however, sections of deformed bedrock in valley walls also
clearly demonstrate regional-scale, thin-skinned glaciotectonic deformation. Southward directed, arcuate, en echelon ridges on either side of the Horton River valley in an area of thin (0-2 m), discontinuous till cover expose massive ice and ice-rich
debris that is interpreted as glacial thrusting of proglacial sediments, possibly buried glacial ice, and underlying bedrock. Elsewhere thick (up to 12 m) layers of buried glacial ice in valley bottoms suggests the potential for long-term
preservation and re-incorporation by subsequent glaciations. The ice-thrust ridges are amongst the only regional-scale surface landforms recognized in the area (i.e. no extensive fluting or drumlin fields), suggesting that while the presence of
patchy till cover indicates warm-based conditions, the thin-skinned tectonics and buried glacier ice, reflect localised basal freeze-on. Thicker tills within the complex stratigraphies of the buried valleys yield clast macrofabrics indicative of long
term ice flow from the east or northeast. The evolution of this landsystem signature likely requires transitory changes in glacier basal thermal regimes possibly in association with advance and retreat of the adjacent westward-flowing Amundsen Gulf
Ice Stream. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Cette étude présente les résultats des travaux sur le terrain entrepris par l¿activité GEM-2 Smoking Hills. Il met en évidence des aspects de
l¿histoire glaciaire de la région et les intègre dans une étude plus large du système terrestre global qui relie les processus glaciaires et géologiques aux formes de relief et à la stratigraphie identifiées. Celles-ci sont ensuite examinées dans le
contexte de la géologie technique et de la manière dont cela peut être appliqué à l'étude et à l'évaluation des environnements de pergélisol arctique glacié. Il est présenté à une conférence de pairs internationaux et à une session extraordinaire
consacrée aux avancées des systèmes paysagers glaciaires et périglaciaires et à leurs implications pour la géologie technique. |
| GEOSCAN ID | 313511 |
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