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TitreComposition of volcanic rocks dredged from the Alpha Ridge, Arctic Ocean
AuteurWilliamson, M -C; Oakey, G N; Hamilton, P B; Jackson, S E; Lawley, C J M; MacDonald, D J; Kellett, D A; Weis, D; Carey, R J; Wilton, D H C; Petts, D C; Massey, E A; Harris, J R
SourceICAM VIII: 8th International Conference on Arctic Margins, abstract volume; .
Séries alt.Ressources naturelles Canada, Contribution externe 20180081
RéunionICAM VIII: 8th International Conference on Arctic Margins; Stockholm; SE; juin 11-14, 2018
Documentlivre
Lang.anglais
Mediaen ligne; numérique
ProgrammePreparation of a submission for an extended continental shelf in the Atlantic and Arctic Oceans under UNCLOS, Délimitation du plateau continental du Canada en vertu de la Convention des Nations Unies sur le droit de la mer (UNCLOS)
Résumé(disponible en anglais seulement)
In August 2016, a collaborative Canada-Sweden Polar Expedition under Canada's UNCLOS (United Nations Convention on Law of the Sea) Program dredged approximately 100 kg of volcanic rocks from the Alpha Ridge. The samples consist of volcanic breccia, carbonate rocks, and a single fragment of fossilized plant material. Here, we report the results of laboratory studies on the sample of volcanic breccia.
The lapilli tuff consists of vitric lapilli clasts, angular lithic clasts of fine-grained, sparsely porphyritic basaltic lava, relict crystals of feldspar and olivine pseudomorphs. Vesicles are flattened and lined with zeolites. The vitric fragments consist of sideromelane glass overprinted by abundant plagioclase microlites. Texturally, these lapilli display a fresh glassy core surrounded by Fe- and Ti-rich zones and a palagonite rim. Major and trace element analyses of glassy cores indicate remarkably uniform, mildly alkaline basaltic compositions. Together with the dominance of glassy vitric clasts in the tuff, this feature suggests a primary eruption-fed origin during a single volcanic event. In contrast, angular clasts of basaltic lava show distinctive geochemical signatures indicating a cognate origin.
Detailed work on the volcanic glass confirms that it is suitable for isotopic studies, 40Ar/39Ar geochronology and an analysis of glass volatiles. To our knowledge, the size and pristine state of the dredged sample of lapilli tuff are unique, allowing our team to carry out the first comprehensive study of a single eruptive event preserved in the volcanic record of the Alpha Ridge.
Résumé(Résumé en langage clair et simple, non publié)
En 2016, la Commission géologique du Canada a prélevé des échantillons de roches par dragage du fond marin aux abords du mont sous-marin Fedotov, sur la crête de la dorsale Alpha, dans l'océan Arctique. Dans cette présentation, nous décrivons les nouvelles données obtenues sur des échantillons de brèche volcanique en soulignant les résultats d`études géochimiques. En plus des résultats de laboratoire, nous proposons une interprétation préliminaire du style d'éruption des roches volcaniques échantillonnées sur la crête de la dorsale Alpha.
GEOSCAN ID308291