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TitreVolcanology and geochemistry of HALIP flood basalts, Axel Heiberg Island, Nunavut
AuteurWilliamson, M C; Saumur, B M; Evenchick, C A; Little, K J; Cousens, B L
Source 2017.
Année2017
Séries alt.Ressources naturelles Canada, Contribution externe 20170002
RéunionGeological Association of Canada-Mineralogical Association of Canada, Annual Meeting,14-18 May, 2017, Kingston, Ontario, Canada; Kingston; CA; mai 14-18, 2017
Lang.anglais
Mediapapier; en ligne; numérique
Référence reliéeCette publication est reliée à Williamson, M -C; Jackson, S E; Yang, Z; Venance, K; Hunt, P; (2018). Magma recharge and mixing processes in continental flood basalt reservoirs: evidence from melt inclusions in basalts from the High Arctic Large Igneous Province, Axel Heiberg Island, Nunavut, Commission géologique du Canada, Dossier public 8377
Formatspdf
ProvinceNunavut
SNRC560B; 69H
Sujetsbasaltes; volcanisme; coulées de lave; Bassin de Sverdrup ; géologie générale; géochimie
ProgrammeLIP de l'haut-Arctique de l'ouest de l'Arctique, GEM2 : La géocartographie de l'énergie et des minéraux
LiensOnline - En ligne
Résumé(disponible en anglais seulement)
Geochemical studies of continental flood basalts are often hindered by a lack of stratigraphic control in areas where sheet flows were emplaced over geologically short time intervals. The advantage of studying flood basalts in a basin setting is that the time-sequence of eruptions is well-defined, thus providing a robust stratigraphic framework for lithogeochemical studies.

Fieldwork in the Sverdrup Basin was carried out in 2015 and 2016 as part of the GEM 2-High Arctic Large Igneous Province (HALIP) research activity. A particular emphasis was placed on the stratigraphy, physical volcanology and geochemistry of flood basalts in the Strand Fiord Formation. Detailed investigations were carried out at two locations on western Axel Heiberg Island: along the south shore of Bunde Fiord, and near Plateau Lake, to the north of Strand Fiord.

Previous studies demonstrated that the ~ 95 Ma Strand Fiord Formation consists of sheet flows of uniformly basaltic composition displaying aa and pahoehoe textures. Fieldwork near Plateau Lake suggests a total thickness of 980 m at this locality. The 3-D exposure of ~500 m of section alongside a retreating glacier makes this an excellent opportunity to study the evolution of a flood basalt province. Invasive flows near the base of the succession consist of a chaotic mélange of basaltic lava and blocks of sandstone. These flows are overlain by a bed of shale containing volcanic bombs and discontinuous lenses of fine-grained sandstone that locally contain fiamme. Thick lava flows are characterized by grey, unoxidized flow tops and show structures such as basalt colonnades and entablatures. In contrast, volcanic successions near Bunde Fiord consist of lava flows separated by well-defined oxidized flow tops. A single bed of crystal tuff occurs near the base of the succession. The flows are uniformly of aa type, and lack the complex intraflow structures observed at Plateau Lake and in the type area at Strand Fiord.

Flood basalts in the Strand Fiord Formation should form a coherent petrogenetic series if individual sections were once part of a single basaltic plateau. A comparative geochemical study of lava flows in both areas suggests that most eruptions tapped steady-state magmas rising from a shallow reservoir. At Bunde Fiord, the mineralogy and geochemistry of lava flows show compelling evidence for episodic magma recharge and mixing processes consistent with periods of quiescence between eruptions. We propose a model for the emplacement of HALIP flood basalts that integrates field observations with the results of petrochemical studies.
Résumé(Résumé en langage clair et simple, non publié)
Cette publication décrit le résultat des activités de cartographie et d'échantillonnage du socle menées dans le cadre de l'activité GEM 2 HALIP. Les auteurs présentent la première étude détaillée du style éruptif dans la formation de Strand Fiord, dans la partie ouest de l'île Axel Heiberg. Les résultats incluent également des données d'éléments majeurs et en traces pour les coulées de lave basaltique échantillonnées dans la succession volcanique d'environ 1 km d'épaisseur. Les auteurs interprètent les tendances de la composition des basaltes de la formation Strand Fiord dans le contexte des autres résultats du projet HALIP. L`étude a des répercussions importantes ayant trait au potentiel économique du système magmatique HALIP dans cette région du Nunavut.
GEOSCAN ID300254