Najat Bhiry (Regular member)
David Didier (Regular member)
Introduction: Paraglacial and postglacial processes have left a sedimentological and morphological heritage in Arctic regions such as Nunavik, northern Québec (Canada) that is still visible today. The general pattern of deglaciation in this region is relatively well-known, but additional studies are needed to establish correlations in all regions of Nunavik. This is the case in southeastern Ungava Bay, which has been the subject of very few studies related to deglaciation and postglacial dynamics. Currently, it is difficult to establish a regional chronostratigraphic model of deglaciation. Although the role of regional topography on the ice margin retreat has been demonstrated in many regions of Nunavik, the influence of the Torngat Mountains in southeastern Ungava Bay is poorly documented.Objectives: The main objective of this project is to develop a model of ice retreat in southeastern Ungava Bay based on the study of paraglacial and postglacial landforms and deposits. Three specific objectives are targeted: 1.To identify the geomorphological landforms attributed to glacier retreat, such as fluvioglacial landforms (eskers, drumlins, ice-contact deltas, kames, etc.) and proglacial landforms (kettles, meltwater channels, moraines, outwash plains, breaded streams, etc.). 2.To identify geomorphological landforms associated with the Iberville marine transgression and regression (deltas, marine terraces, uplifted shores, washout limits, etc.) 3.To study the stratigraphy of the deposits that build these landforms, to reconstruct their sedimentary environments and to validate the geomorphological analyses. Study sites: The study region includes southeastern Ungava Bay (Nunavik) and incorporates the middle and downstream valleys of the George and Koroc rivers. It also includes the Inuit village of Kangiqsualujjuaq and part of the Kuururjuaq National Park, which runs along the Koroc River basin from the foothills of the Torngat Mountains. The region is at the confluence of three natural regions: the coast of Ungava Bay to the northwest, the George River Plateau to the west, and the foothills of the Torngat Mountains to the east. The region is part of the southeastern Churchill Province, which includes highly metamorphic rocks, a phenomenon attributed to the Torngat orogeny. The landscape is mostly bare, as it is in the herbaceous Arctic tundra bioclimate; the vegetation is dominated by grass, moss and lichen.Material and methods: Stratigraphic sections at the mouth of the George River were analysed in the summer of 2022 and sampled for analytical analyses. Additional sections along major rivers will be studied in summer 2023. A geomorphological analysis of the forms attributed to the retreat of the glacier and the transgression and regression of the Iberville Sea will be performed using aerial photographs and satellite imagery. The identified landforms will be mapped using ESRI ArcGIS pro software. The results will then be validated by fieldwork in July 2023 and selected sites will be examined prior to sampling for sedimentological (particle size, magnetic susceptibility) and chronological analysis.References: Daigneault, R-A. et Bouchard, M. A. 2004. Les écoulements et le transport glaciaires dans la partie septentrionale du Nunavik (Québec). Canadian Journal of Earth Sciences 41 (8) : 919-938. Daigneault, R-A. 2008. Géologie du Quaternaire du nord de la péninsule d’Ungava, Québec. Commission géologique du Canada, bulletin 533. 115 p. Lajeunesse, P. et Allard, M. 2003. Late Quaternary deglaciation, glaciomarine sedimentation and glacioisostatic recovery in the Rivière Nastapoka, eastern Hudson Bay, northeastern Québec. Géographie physique et Quaternaire 57 (1): 65-83.
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