| Titre | The morphosedimentary record of glacial to postglacial environmental changes in fjord-lake Mékinac and adjacent areas (southeastern Canadian Shield) |
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| Auteur | Trottier, A -P; Brouard, E; Lajeunesse, P; Normandeau, A |
| Source | Geomorphology vol. 376, 107565, 2020 p. 1-13, https://doi.org/10.1016/j.geomorph.2020.107565 |
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| Année | 2020 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20200035 |
| Éditeur | Elsevier B.V. |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1016/j.geomorph.2020.107565 |
| Media | papier; en ligne; numérique |
| Formats | pdf; html |
| Province | Québec |
| SNRC | 31I/15; 31P/02 |
| Région | Lake Mékinac; Du-Milieu River; Les Laurentides |
| Lat/Long OENS | -72.7500 -72.5000 47.2500 46.8833 |
| Sujets | antecedents glaciaires; glaciation; déglaciation; marges glaciaires; antécédents tectoniques; relèvement isostatique; secousses séismiques; milieu côtièr; bassins; fjords; eaux de surface; lacs;
paléoenvironnement; paléoclimats; levés géophysiques; levés acoustiques; bathymétrie; topographie; topographie glaciaire; dépôts glaciaires; dépôts proglaciaires; dépôts postglaciaires; dépôts de glissement de terrain; mouvement de masse; deltas;
Bouclier Canadien; Calotte glaciaire Laurentide; Flux de glace du Saint Laurent; sédiments alluviaux; géologie marine; géologie des dépôts meubles/géomorphologie; sédimentologie; stratigraphie; géologie de l'environnement; géophysique; Nature et
environnement; Sciences et technologie; Phanérozoïque; Cénozoïque; Quaternaire |
| Illustrations | cartes de localisation; cartes géolscientiques généralisées; images géophysiques; tableaux; profils; profils géophysiques; coupes schématiques transversales |
| Diffusé | 2020 12 09 |
| Résumé | (disponible en anglais seulement)
Fjords can transition from marine embayments to lacustrine waterbodies under glacio-isostatic change following their deglaciation. However, little is known on
how a transition from fjord to lake is influenced by glacial dynamics and how it influences sedimentation in and around the basin. Here, we analyse swath bathymetry imagery and subbottom profiles pri in Lake Mékinac (southern Québec) as well as
glacial landforms from LiDAR imagery around the lake to document the evolution of a fjord basin into a lacustrine body during the transition from the Late Pleistocene to the Holocene. These analyses helped refine local glacial history and show that
the study area was probably under the up-ice reach of the St. Lawrence Ice Stream during full glacial conditions. The mapping of moraines in and around Lake Mékinac shows that deglaciation of the study area was marked by stabilization of the
ice-margin during the Mars-Batiscan Event, which is traditionally correlated to the climate deterioration at the end of the Younger Dryas. The architecture of acoustic facies in the lake indicates a transition from glacial conditions (U1), to
proglacial-paraglacial (U2) and to postglacial conditions (U3). The bottom of Lake Mékinac also contains multiple mass movement deposits related to progradation of the Du-Milieu River delta and probably to late-Holocene earthquakes. The acoustic
architecture of sediments within the lake indicates that the sedimentation regime was most dependant on the sediment input regime and that the transition from fjord to lake did not significantly influence sedimentation during deglaciation of the
watershed. Further work on dating the mass movement deposits that characterise the sediment architecture should provide a better assessment of natural hazard associated with seismological events. |
| Sommaire | (Résumé en langage clair et simple, non publié)
L'étude de la transition d'un fjord marin à un environnement lacustre donne un aperçu de la géométrie de la marge glaciaire, de la dynamique des
glaces, de l'ajustement glacio-isostatique et de l'activité des pentes paraglaciaires du sud du Québec. |
| GEOSCAN ID | 326021 |
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