La moraine frontale de Sakami, Québec subarctique
The Sakami Moraine, 630 km long, forms the largest accumulation of unconsolidated material in subarctic Québec. It stretches between the southern tip of Lake Mistassini and the mouth of the Great Whale River, forming a semicircular arc centered in the middle of Québec. It is composed of glacio-fluvi...
| Published in: | Géographie physique et Quaternaire |
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| Format: | Text |
| Language: | French |
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Les Presses de l'Université de Montréal
1982
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| Online Access: | https://doi.org/10.7202/032469ar http://id.erudit.org/iderudit/032469ar |
| Summary: | The Sakami Moraine, 630 km long, forms the largest accumulation of unconsolidated material in subarctic Québec. It stretches between the southern tip of Lake Mistassini and the mouth of the Great Whale River, forming a semicircular arc centered in the middle of Québec. It is composed of glacio-fluvial and proglacial materials usually forming vast deltaic plains or large asymmetric ridges 8 km x 6 km x 40 m thick. The Sakami Moraine is a morpho-stratigraphic unit of prime importance in the déglaciation history of the James Bay hydrographie basin. It shows the position occupied by the eastward retreating New-Québec glacier when glacial Lake Ojibway drained and the Tyrrell Sea invaded the lowlands. It also demarcates two styles of ice retreat, one in contact with a deep lacustrine water body where a rapid ice front retreat was occurring mostly by icebergs calving from a locally floating ice margin, the other one in a subaerial environment or in contact with a shallower marine body where the melting of an ice margin resting on its bed was resulting in slower ablation. The Sakami Moraine was in its building phase 7900 14C years ago Avec ses quelque 630 km de longueur, la moraine frontale de Sakami constitue la forme glaciaire la plus importante du Québec subarctique. Elle s'étire entre le sud du lac Mistassini et l'embouchure de la grande rivière de la Baleine en décrivant un arc de cercle dont le point central est situé au centre du Québec. Elle se compose de matériaux fluvio-glaciaires et proglaciaires qui forment le plus souvent de vastes plaines deltaïques ou de longues crêtes dissymétriques dont les dimensions peuvent atteindre 8 km x 6 km x 40 m. La moraine de Sakami constitue une unité morpho-stratigraphique de première importance dans l'histoire de la déglaciation du bassin hydrographique de la baie James. Elle localise la position occupée par le glacier du Nouveau-Québec, qui se retirait vers l'est, lors du drainage du lac glaciaire Ojibway et de l'invasion de la mer de Tyrrell. Par cette position, elle ... |
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