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TitreCompositional changes in deglacial red mud event beds off the Laurentian Channel reveal source mixing, grain-size partitioning and ice retreat
AuteurLeng, W; von Dobeneck, T; Just, J; Govin, A; St-Onge, G; Piper, D J W
SourceQuaternary Science Reviews vol. 215, 2019 p. 98-115, https://doi.org/10.1016/j.quascirev.2019.04.031
Année2019
Séries alt.Ressources naturelles Canada, Contribution externe 20180365
ÉditeurElsevier BV
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1016/j.quascirev.2019.04.031
Mediapapier; en ligne; numérique
Formatspdf (Adobe® Reader®)
ProvinceTerre-Neuve-et-Labrador; Nouvelle-Écosse; Nouveau-Brunswick; Île-du-Prince-Édouard; Québec; Région extracotière de l'est
SNRC1; 2; 10; 11; 12; 20; 21; 22
Lat/Long OENS -72.0000 -52.0000 52.0000 43.0000
Sujetsmarges continentales; plate-forme continentale; talus continental; antecedents glaciaires; nappes glaciaires; déglaciation; retrait de la glace; antecedents de sedimentation; sédiments marins; boues; débris; couches rouges; moraines; lithologie des galets; origine; régions émettrices; repartition granulométrique; géochimie des éléments majeurs; propriétés magnétiques; magnetite; hématite; transport des sediments; dispersion des sédiments; profils de dispersion; dispersion géochimique; distribution des éléments; distribution minérale; modèles; échantillons carrotés; géologie du substratum rocheux; lithologie; analyses stratigraphiques; corrélations stratigraphiques; Calotte glaciaire Laurentide; Bouclier Canadien; Province Appalachienne; sédiments glaciomarins; géologie marine; géologie des dépôts meubles/géomorphologie; géochimie; minéralogie; stratigraphie; Phanérozoïque; Cénozoïque; Quaternaire
Illustrationsgeoscientific sketch maps; bar graphs; plots; profiles; geophysical images; frequency distribution diagrams; tables; 3-D diagrams; ternary diagrams; models
ProgrammeGéo-risques marins, Géoscience pour la sécurité publique
Diffusé2019 05 23
Résumé(disponible en anglais seulement)
Between 22 and 17 cal ka BP, five large meltwater events from within the Laurentian Channel Ice Stream deposited mud beds meters thick across a large area of the Laurentian Fan and adjacent continental slopes. This study determines the sources of these event beds and relates them to the glaciological evolution of the retreating Laurentian Ice Stream. We analyzed major element and magnetic mineral contents of these event beds and compare them with a new collection of 80 source reference samples from the Gulf of St. Lawrence area. Element ratios suggest a steady compositional change from older to younger outburst event beds, while element-specific offsets from reference sample compositions indicate grain-size and mineral/element partitioning during suspension transport. Their magnetic properties place event beds on the source mixing trend of four reference samples groups, which represent two magnetite-rich sources (Canadian Shield and/or Southern Newfoundland) and two hematite-rich sources (Appalachian red beds). Using a deterministic linear source mixing model based on IRM100mT, HIRM and Ca%, we find that the earlier two outburst events had higher contributions from granitic and calcareous sources than the later three events. Combining materials, timing and scenarios of the outburst events with ice-sheet retreat and ice-stream dynamics, we argue that the subglacial sediment depocenter of the earlier two event beds was located in the lower Laurentian Channel while that of the later three events was upstream from Cabot Strait.
Résumé(Résumé en langage clair et simple, non publié)
Cette étude identifie les sources changeantes de dépôts de boue très épais dans les eaux profondes au large de la Nouvelle-Écosse. Le dépôt rapide de ces lits les rend particulièrement vulnérables aux glissements de terrain sous-marins.
GEOSCAN ID313532