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TitreDeglaciation and ice shelf development at the northeast margin of the Laurentide Ice Sheet during the Younger Dryas chronozone
AuteurFurze, M F A; Pienkowski, A J; McNeely, M A; Bennett, R; Cage, A G
SourceBoreas 2017, 26 pages, https://doi.org/10.1111/bor.12265
Année2017
Séries alt.Secteur des sciences de la Terre, Contribution externe 20160266
ÉditeurJohn Wiley & Sons Ltd.
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1111/bor.12265
Mediapapier; en ligne; numérique
Formatspdf
ProvinceRégion extracotière du nord; Nunavut
SNRC48C; 48D; 48E; 48F
Lat/Long OENS -90.0000 -75.0000 75.0000 72.0000
Sujetsglaciation; déglaciation; transport par radeaux de glace; biostratigraphie; lithofaciès; mouvement de masse; courants glaciaires
Illustrationslocation maps; geological sketch maps; lithologic logs; tables; graphs; schematic diagrams
ProgrammeRisques géo marines, Géoscience pour la sécurité publique
Résumé(disponible en anglais seulement)
Core 2011804-0010 from the intersection of Lancaster Sound and Baffin Bay provides important insights into deglacial timing and style at the marine margin of the NE Laurentide Ice Sheet. Spanning 13.0-10.7 cal ka BP and investigated for ice-rafted debris (IRD), calcareous microfossils, and biogeochemistry (biogenic silica, total organic carbon), the record shows a lithofacies progression from proximal
grounding line to distal calving margin sub-ice shelf environments to open glacimarine deposition; a sequence consistent with records described from Antarctic ice shelves. IRD initially reflects input from northern Baffin Island via an Admiralty Inlet trunk glacier to eastward-streaming ice in Lancaster Sound. This is succeeded by the increasing importance of Bylot Island sources following ice shelf break-up.
Foraminiferal faunas are dominated by characteristic ice-proximal glacimarine benthics (Cassidulina reniforme, Elphidium excavatum f. clavata), complemented by advected Atlantic water (Cassidulina neoteretis, Neogloboquadrina pachyderma) and enhanced current indicators (Lobatula lobatula). The biostratigraphy, coupled with biogeochemistry, further supports the ice shelf model, with advection of sparse faunas beneath the ice shelf, followed by increased productivity under open glacimarine conditions.
Results imply the existence of grounded ice in eastern Lancaster Sound at and following the Last Glacial Maximum, and consequently along northern Bylot Island. Initial float-off of grounded ice occurred >13.0 cal ka BP, followed by a persistent extensive glacial ice shelf stabilizing the retreating margin of the Laurentide Ice Sheet in eastern Lancaster Sound until ~12.2 cal ka BP. Absent Holocene deposits and the site's proximity to tidewater glacial sediment sources and 20th century earthquake foci 23 suggest loss of the upper record due to mass sediment transport, potentially due to Holocene seismic activity. Collectively, this study represents the first marine evidence for deglacial ice shelves in the eastern Northwest Passage, with implications for deglacial dynamics, ice sheet stability, and ice-ocean interactions in this complex archipelago setting.
Résumé(Résumé en langage clair et simple, non publié)
Le présent document porte sur de nouvelles interprétations et la chronologie des processus de déglaciation dans l'est du détroit de Lancaster et la baie de Baffin. Vraisemblablement, 'instabilité du talus expliquerait l'absence de sédiments récents (moins de 10 000 ans) observée dans les échantillons de carottes analysés en vue du présent rapport.
GEOSCAN ID299424