| Titre | Glacial landforms and sediments (landsystem) of the Smoking Hills area, Northwest Territories, Canada: implications for regional Pliocene-Pleistocene Laurentide Ice Sheet dynamics |
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| Auteur | Evans, D J A; Smith, I R ; Gosse, J C; Galloway, J M |
| Source | Quaternary Science Reviews vol. 262, 106958, 2021 p. 1-50, https://doi.org/10.1016/j.quascirev.2021.106958  Accès ouvert |
| Année | 2021 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20200754 |
| Éditeur | Elsevier |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1016/j.quascirev.2021.106958 |
| Media | papier; en ligne; numérique |
| Formats | pdf; html |
| Province | Territoires du Nord-Ouest |
| SNRC | 97A/05; 97A/12; 97A/13; 97B/05; 97B/06; 97B/07; 97B/08; 97B/09; 97B/10; 97B/11; 97B/12; 97B/13; 97B/14; 97B/15; 97B/16; 97C; 97D/04; 97D/05; 97D/12; 97D/13; 97F; 107A/05; 107A/06; 107A/07; 107A/08; 107A/09;
107A/10; 107A/11; 107A/12; 107A/13; 107A/14; 107A/15; 107A/16; 107D; 107E |
| Région | Smoking Hills; Cape Bathurst; Parry Peninsula; Franklin Bay; Amundsen Gulf; Horton River |
| Lat/Long OENS | -132.0000 -123.0000 70.7500 68.2500 |
| Sujets | Pléistocène; Néogène; Pliocène; dépôts organiques; plaines d'inondation; terrasses; deltas; chenaux; dépôts glaciaires; topographie glaciaire; elements glaciaires; tills; moraines; rainures glaciaires;
écoulement glaciaire; lacs glaciaires; tectonites; graviers; eskers; chenaux d'eau de fonte; kames; kettles; buttes; antecedents glaciaires; Wisconsinien; glaciation; nappes glaciaires; marges glaciaires; déglaciation; retrait de la glace; stades
interglaciaires; pergélisol; fentes de glace; époques paléomagnétiques; interprétations paléomagnétiques; stratigraphie systématique; corrélations stratigraphiques; historique de l'enfouissement; tectonique glaciaire; formation de failles; failles,
chevauchement; déformation; sédimentation; déplacement des sédiments; datation radiométrique; datation au radiocarbone; paléogéographie; lithofaciès; Calotte glaciaire Laurentide; Formation de Beaufort ; Formation de Mason River ; sédiments
fluvioglaciaires; sédiments glaciolacustres; courants glaciaires; directions d'écoulement glaciaire; sédiments alluviaux; sédiments de cônes d'épandages proglaciaires; chenaux-déversoirs; géologie des dépôts meubles/géomorphologie; stratigraphie;
géophysique; sédimentologie; géologie structurale; géochronologie; géologie régional; géochimie; Nature et environnement; Sciences et technologie; Phanérozoïque; Cénozoïque; Quaternaire; Tertiaire; Mésozoïque; Crétacé |
| Illustrations | cartes de localisation; cartes géolscientiques généralisées; modèles altimétriques numériques; photographies; graphique à barres; diagrammes ternaires; diagrammes à secteurs; graphiques;
photographies aériennes; images satellitaires; croquis; coupes lithologiques; diagrammes stéréographiques tournant de wulff; coupes de corrélation; séries chronologiques; tableaux |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Smoking Hills, géologie tertiaire du territoire de l'ouest de l'Arctique |
| Programme | Programme du plateau continental polaire |
| Diffusé | 2021 06 02 |
| Résumé | (disponible en anglais seulement)
The Smoking Hills area in the western Canadian Arctic was purported to contain a regionally rare Quaternary stratigraphic section with multiple, local ice
cap-derived tills and a long chronology constrained by palaeomagnetic markers. We present a fundamental revision of previous glacial and magnetostratigraphic interpretations based on detailed sedimentological and structural analyses of the main
stratigraphic section and many new exposures, cosmogenic nuclide isochron burial dating, and a systematic reconstruction of the geomorphology and landscape evolution using a glacial landsystem approach. We demonstrate that the Smoking Hills area was
fully glaciated during the last (Wisconsinan) glaciation. Previously reported tills ascribed to multiple glaciations represent instead a complex facies sequence of glacitectonic thrust stacking of Laurentide Ice Sheet (LIS) sourced diamictons,
glacilacustrine and glacifluvial deposits, together with previously unidentified, poorly-consolidated Cretaceous bedrock rafts and deformed intraclasts. Much of this sedimentation and glacitectonic activity dates to the last (Wisconsinan) glaciation
and can be reconciled with a polythermal ice sheet marginal landsystem signature, wherein ice-cored moraine belts are developed over subglacial bedforms (flutings) arranged in discrete flowsets. The flowsets record the complex interaction of ice
streams nourished by ice flowing from three main sources: Great Bear Lake to the south, Amundsen Gulf (Franklin Bay) to the east and Liverpool Bay (Mackenzie Valley) to the southwest. Decoupling of the ice margins of these three ice sources gave rise
to interlobate ice-dammed lake development over the lower Horton River area during final deglaciation. A cosmogenic 26Al/10Be isochron burial age of 2.9 ± 0.3 Ma (1sigma, n = 4) from the lowermost glacial diamicton and glacitectonite sequence
provides evidence of perhaps the earliest continental glaciation of this region. This deposit postdates, or is perhaps a later re-advance of the same initial glaciation that produced widespread glacitectonic disturbance of bedrock in preglacial
valley networks and early glacifluvial and glacilacustrine deposits containing an ice wedge pseudomorph. Subsequent glaciations have largely removed or cannibalised pre-existing records to construct complex till and glacitectonite stacks that contain
reworked organics with non-finite radiocarbon ages. One site preserves buried 'old' glacier ice in which prominent ice wedges had formed during an interglacial permafrost phase and were then deformed down-flow by the LIS during the Wisconsinan
glaciation. |
| Sommaire | (Résumé en langage clair et simple, non publié)
This article summarizes new research on the glacial history of the Smoking Hills area in the Northwest Territories. It offers an important
review of previous glacial reconstructions and represents the first study to identify and date the oldest known continental glaciation in northwestern Canada (2.9 Ma). The article describes the preservation of "old" ice from the Ice Age buried at a
site pre-existing to the last ice age, which is important given the long-term stability of the permafrost in Canada's North. The present study proves that the region was completely icy during the last ice age, a hypothesis that has been debated for a
long time. Therefore, the present work will strengthen new models of past glacial dynamics, which is important in view of regional mineral dispersion studies. This work will also support ongoing research studying the rapid and extensive melting of
ice-rich permafrost and its impact on the acceleration of bedrock slide in the region. |
| GEOSCAN ID | 328125 |
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