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TitreSub-bottom profiling and coring of sub-basins along the lower French River, Ontario: insights into depositional environments within the North Bay outlet
AuteurBrooks, G R; Medioli, B E
SourceJournal of Paleolimnology vol. 47, 2012 p. 447-467,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20080597
Documentpublication en série
Mediapapier; en ligne; numérique
SNRC31L/04; 31L/05; 31L/06; 41I/01; 41I/02
Lat/Long OENS-81.2500 -79.0000 46.5000 45.7500
SujetsHolocène; bassins; analyse du bassin; lacs; sédiments de fond; épaisseur des sediments lacustres; sediments lacustres; carottes de sediments lacustres; dépôts lacustres; milieux lacustres; milieu hydrologique; Bassin d'Huron ; Changement climatique; hydrogéologie; géologie de l'environnement; Cénozoïque
Illustrationslocation maps; stratigraphic columns; tables; profiles; photographs
ProgrammeÉtudes paléo-environnementales sur les changements climatiques, Géosciences de changements climatiques
ProgrammeRenforcer la résilience face aux changements climatiques
Résumé(disponible en anglais seulement)
Sub-bottom profiling was conducted at eight sub-basins within the lower French River area, Ontario, to investigate deposits preserved within the ancient North Bay outlet. Ten cores were collected that targeted the four depositional acoustic facies identified in the sub-bottom profiling records. The rhythmically laminated/bedded glaciolacustrine deposits of facies I are interpreted to have aggraded within glacial Lake Algonquin and its associated recessional lakes that persisted between 13,000 and 11,300 cal BP (*11,100 and 9,900 BP). The majority of the facies II, III and IV lacustrine deposits accumulated between about 9,500 cal BP (*8,500 BP) and the mid-Holocene, based on radiocarbondated organic materials. These deposits represent sedimentation within a 'large' lake during the late portion of the Mattawa-Stanley phase, and the Nipissing transgression, Nipissing Great Lakes and post-Nipissing recession phases of lake levels. Two sets of organic-rich sand beds are preserved within facies II deposits and reveal that the large lake lacustrine depositional environment was interrupted during the late Mattawa-Stanley phase between 9,500 - 9,300 and 9,000 - 8,400 cal BP (*8,500 - 8,300 and *8,000 - 7,600 BP), when the water surface of Lake Hough fell below the outlet threshold and the lake basin became hydrologically closed. Pre- 9,500 cal BP (*8,500 BP), the early and middle portions of the Mattawa-Stanley phase were dominated by erosion, as reflected by an unconformity at the base of facies II that occurs widely in the subbasins and the general lack of preserved deposits for these intervals in the cores. This erosion is attributed to wave action and fluvial scouring within the outlet mouth during the early and mid-Stanley-Hough low stages and relates specifically to the period when the flowing portion of the North Bay outlet was situated over the lower French River area. This study reveals that the majority of the post-glacial deposits accumulated after the outlet threshold had shifted permanently eastwards and the lower French River area was inundated under the multiple phases of the large lake occupying the Nipissing Lowlands and Georgian- Huron basins, extending well into the mid-Holocene. The occurrence of deposits marking two closed-basin intervals during the late Stanley-Hough stage are well preserved locally within the lacustrine depositional sequence, but identifying earlier closed-basin intervals from the French River stratigraphy is hindered by the lack of preserved pre-9,500 cal BP (*8,500 BP) post-glacial deposits.