| Titre | Comparative geochemistry of volcanic rocks dredged from the Alpha Ridge and HALIP volcanic-intrusive complexes, northern Ellesmere Island, Canadian Arctic |
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| Auteur | Williamson, M -C ;
Weis, D; Saumur, B; Kingsbury, C G; Kellett, D; Davis, B; Oakey, G; Shimeld, J; MacDonald, D; Jackson, S; Lawley, C; Petts, D; Abraham, A |
| Source | Chapman Conference: Large-scale Volcanism in the Arctic: The Role of the Mantle and Tectonics, abstracts; 2019 p. 74-75  Accès ouvert |
| Liens | Online - En ligne (complete volui\me - volume complet, PDF, 3.32 MB)
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| Image |  |
| Année | 2019 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20190138 |
| Éditeur | American Geophysical Union |
| Réunion | Chapman Conference: Large-scale Volcanism in the Arctic: The Role of the Mantle and Tectonics; Selfoss; IS; Octobre 13-18, 2019 |
| Document | livre |
| Lang. | anglais |
| Media | en ligne; numérique |
| Formats | pdf |
| Province | Nunavut |
| SNRC | 39E; 39F; 39G; 39H; 49E; 49F; 49G; 49H; 59E; 59F; 59G; 59H; 120; 340; 560 |
| Région | île d'Ellesmere; Heiberg Island; Canadian Arctic Islands |
| Lat/Long OENS | -96.0000 -52.0000 84.0000 78.0000 |
| Sujets | antécédents tectoniques; magmatisme; volcanisme; intrusions; filons rocheux; filons-couches; géologie du substratum rocheux; lithologie; roches ignées; roches volcaniques; coulées de lave; basaltes;
trachybasaltes; rhyolites; tufs volcaniques; volcanoclastique; roches intrusives; gabbros; datation radiométrique; datation argon-argon; etudes isotopiques; rapports strontium-strontium; néodyme; interprétations géophysiques; interprétations
magnétiques; Formation d'Isachsen ; Formation de Strand Fiord ; Formation d'Hassel ; géochimie; pétrologie ignée et métamorphique; géochronologie; géophysique; Sciences et technologie; Nature et environnement; Phanérozoïque; Mésozoïque;
Crétacé |
| Programme | Délimitation du plateau continental du Canada en vertu de la Convention des Nations Unies sur le droit de la mer (UNCLOS) |
| Diffusé | 2019 10 01 |
| Résumé | (disponible en anglais seulement)
The Canadian portion of the High Arctic Large Igneous Province (HALIP) ranges in age from ~125 to 80 Ma. On Axel Heiberg Island and northern Ellesmere Island,
the HALIP was emplaced episodically at several volcanic-intrusive complexes (VIC). Each VIC is characterized by a distinct eruptive style, narrow range of crystallization ages and geochemical signature. On Axel Heiberg Island (Type 1 VIC; ~120-95
Ma), tholeiitic lava flows and associated gabbroic sills and dykes of subalkaline affinity predominate. Type 1 VICs include the Surprise Fiord and Lightfoot River dyke swarms; Buchanan Lake sill complex; South Fiord and Middle Fiord complexes; and
lava flows in the Isachsen Formation and Strand Fiord Formation. On northern Ellesmere Island (Type 2 VIC; ~92-90 Ma) igneous rocks consist of olivine normative, mildly alkaline (transitional) ferrobasaltic lavas and gabbros (Tanquary Fiord and
Ekblaw Lake sills; Piper Pass intrusive complex; Wooton Igneous Complex; and lava flows in the Hassel Formation). The Hansen Point Rift Volcanics (HPRV; Type 3 VIC; ~80 Ma) consist of alkali olivine basalt, trachybasalt and rhyolite erupted from
volcanic centres and lava domes. The classification of HALIP rocks into VICs enables a comparison with volcanic rocks dredged from the Alpha Ridge (AR) under Canada's United Nations Convention on Law of the Sea (UNCLOS) Program. The samples consist
of lapilli tuff with vitric and lithic fragments. The juvenile clasts consist of mildly alkaline (transitional) basalt glass with abundant plagioclase microlites. The plagioclase microlites yielded a 90 Ma 40Ar/39Ar age. Cognate basalt clasts are
comagmatic volcanic rocks that were explosively broken and mixed with juvenile magma during eruption. A large basalt clast extracted from the AR lapilli tuff yielded 87Sr/86Sr of 0.703148 and epsilon-Nd of +7.24. The AR sample plots in the mantle
array and shows a close geochemical affinity with ferrogabbros of the Piper Pass intrusive complex and some Mg-rich basaltic lavas in the HPRV. This isotopic similarity suggests that the AR lapilli tuff is contemporaneous with VICs exposed on
northern Ellesmere Island. The Alpha Ridge and Type 2 VIC characteristically display high magnetic anomalies that could result from the emplacement of predominantly ferrobasaltic magmas in the interval 95-90 Ma. |
| Sommaire | (Résumé en langage clair et simple, non publié)
En août 2016, environ 100 kg de roches volcaniques ont été récupérées avec succès de la dorsale Alpha, dans l'océan Arctique, dans le cadre du
Programme de la marge continentale étendue du Canada (UNCLOS Programme). Les échantillons sont constitués de roches pyroclastiques (tuf à lapilli) mises en place lors d¿une éruption explosive. L'âge de ces roches correspond à celui des roches
volcaniques et intrusives de la grande province ignée de l¿Extrême-Arctique affleurant au nord de l'île d'Ellesmere. En comparant les données géochronologiques, géochimiques et minéralogiques, nous concluons que les roches ignées terrestres et
extracôtières proviennent de la même source mantéllique. |
| GEOSCAN ID | 314825 |
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