Glacial-Marine Sedimentation, Canadian Polar Margin, North of Axel Heiberg Island
Sediment cores, taken at depths of 140 to 300 m across the northwestern shelf of Axel Heiberg Island (82° N), record the deposition of sediments under perennial sea ice. Five sedimentary fades are recognized: (A) soft pebbly-sandy-mud with dropstone structures; (B) bioturbated silty muds; (C) wispy-...
| Published in: | Géographie physique et Quaternaire |
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| Main Authors: | , |
| Format: | Text |
| Language: | English |
| Published: |
Les Presses de l'Université de Montréal
1991
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| Subjects: | |
| Online Access: | http://id.erudit.org/iderudit/032861ar https://doi.org/10.7202/032861ar |
| Summary: | Sediment cores, taken at depths of 140 to 300 m across the northwestern shelf of Axel Heiberg Island (82° N), record the deposition of sediments under perennial sea ice. Five sedimentary fades are recognized: (A) soft pebbly-sandy-mud with dropstone structures; (B) bioturbated silty muds; (C) wispy-laminated silty clay/clay; (D) laminated sands/silts and mud; (E) firm pebbly-sandy-mud with chaotic pebble fabrics. Other sediments include terrestrial bedrock of Paleogene Eureka Sound Group, and a younger Tertiary deposit, possibly the Beaufort Formation. Ages range from 1530 ± 60 BP (Fades A) to 9950 ± 80 BP (Fades D). Sedimentation rates vary as follows: - 0.8 cm ka-1, Fades B; 4 cm ka"\ Fades A; 90 cm ka-1, Fades C; 134 cm ka~', Fades D. The sedimentation history, as interpreted from the sedimentology, palynology and foraminiferal results, suggests intervals of more continuous ice cover, with a reduced influx of coarse ice-rafted detritus, alternating with more open water conditions, and high sediment input from meltwater and/or floating icebergs. Only marine sediments overlie Neogene bedrock in the cores. The absence of diamictons at the core sites suggests that grounded ice perhaps never occupied this part of the Axel Heiberg Island shelf. The interpreted history of sedimentation generally corresponds to the land-based record from Ellesmere Island, but differs significantly from marine-based studies in more southern latitudes. L'étude des carottes de sédiments recueillies à des profondeurs de 140 à 300 m sur la plate-forme de l'île Axel-Heiberg (82° N) renseigne sur la mise en place des sédiments sous une glace de mer pérenne. Elle révèle cinq faciès sédimen-taires: (A) boue sablo-caillouteuse avec structures de cailloux de délestage; (B) boues silteuses bioturbées; (C) lamines en mèches d'argile et d'argile silteuse; (D) sables et silts laminés et boue; (E) boue sablo-caillouteuse compacte. Les carottes renferment aussi des sédiments du substratum du Groupe de Eureka Sound du Paléogène et un dépôt tertiaire ... |
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