| Titre | Middle Wisconsinan marine shells near Repulse Bay, Nunavut, Canada: implications for MIS 3 ice-free conditions in northwest Hudson Bay |
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| Auteur | McMartin, I ;
Campbell, J; Dredge, L |
| Source | 20th Congress of the International Union for Quaternary Research (INQUA), online programme; 2019 p. 1  Accès ouvert |
| Liens | Online - En ligne
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| Image |  |
| Année | 2019 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20180359 |
| 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 (Adobe® Reader®) |
| Province | Nunavut |
| SNRC | 46E/14; 46E/15; 46E/16; 46F/13; 46K/04; 46K/05; 46L/01; 46L/02; 46L/03; 46L/06; 46L/07; 46L/08 |
| Région | Repulse Bay; Baie d'Hudson |
| Lat/Long OENS | -87.0167 -85.8833 66.4500 65.9167 |
| Sujets | antecedents glaciaires; glaciation; écoulement glaciaire; glaciation; retrait de la glace; marges glaciaires; Wisconsinien; submersion; régions émettrices; fossiles; datation radiométrique; datation au
radiocarbone; dépôts glaciaires; roches mères; modèles; Calotte glaciaire Laurentide; Basses-Terres de la Baie d'Hudson; tills fuselés, carbonatés; courants glaciaires; directions d'écoulement glaciaire; limites de glaciation; submersion, marine;
géologie des dépôts meubles/géomorphologie; paléontologie; géochronologie; Nature et environnement; Phanérozoïque; Cénozoïque; Quaternaire |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Synthèse de l'histoire glaciaire de la province de Rae |
| Diffusé | 2019 07 01 |
| Résumé | (disponible en anglais seulement)
Evidence suggesting reduction of the Laurentide Ice Sheet (LIS) during MIS 3 is widespread but the boundaries of the ice sheet and timing of the minimum ice
extent are still poorly constrained. The idea that the Middle Wisconsin was a period of significant glacial recession in the core area of the LIS has long been debated, and is still disputed today, particularly in the Hudson Bay Lowlands (HBL).
Radiocarbon dating of glacially transported marine molluscs in streamlined till south of Repulse Bay, Nunavut, Canada, provides new evidence for MIS 3 deglaciation in the northwest part of Hudson Bay. Middle Wisconsinan finite 14C ages on 8 mollusc
samples varying between 31.7 and 39.2 14C ka BP (~35.0 and 43.7 cal ka BP) indicate a marine event(s) for a minimum of ~8.7 cal ka. The fossiliferous calcareous till is derived from Paleozoic carbonates in proto-Roes Welcome Sound, and was deposited
by a topographically controlled ice stream stemming from the eastern end of the Keewatin Ice Divide. Our findings suggest prior ice-free conditions in the ice stream source area indicating significant glacial recession of the LIS margin during the
Middle Wisconsinan, much farther in the interior of the ice sheet than previously known. We propose here various possible configurations of ice limits during MIS 3 for the extended Repulse Bay region. The marine incursion possibly occurred as a
result of a calving bay developed from the north in the Gulf of Boothia-Committee Bay area following the recession and collapse of an ice stream which was re-activated after the MIS 3 marine episode(s), and maintained until deglaciation.
Alternatively, the development of a calving bay(s) from the east up Hudson Strait may have permitted deglaciation of Roes Welcome Sound and possibly other parts of Hudson Bay. Although these configurations of the LIS may not answer the recurring
question whether MIS 3 was a time when the HBL were ice free, they significantly contrast with recent paleo-ice sheet models that suggest full ice conditions in the Repulse Bay region and can therefore contribute to the debate and configuration of
the LIS during MIS 3. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Jusqu'alors inconnus, des sédiments glaciaires provenant d'une source lointaine et contenant de petits fragments de coquillages marins anciens
qui remontent à une époque d'avant le dernier maximum glaciaire ont été découverts près du village de Repulse Bay, au Nunavut central continental. Cette découverte a des implications pour l'histoire de la calotte laurentidienne parce qu'elle indique
la déglaciation partielle du coeur de l'Inlandsis durant le milieu d'une période glaciaire, et fournit de nouvelles connaissances géologiques sur la provenance des matériaux de surface. Ces matériaux sont utilisés pour retracer des débris minéralisés
à leurs sources dans le substratum rocheux dans des terrains anciennement couverts par les glaciers. Ce travail fait partie des activités Wager Bay Nord et Synthèse glaciaire dans le Rae à la Commission géologique du Canada, dans le cadre du
Programme en géocartographie de l'énergie et des minéraux (GEM1&2) de Ressources Naturelles Canada. |
| GEOSCAN ID | 313522 |
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