| Titre | New constraints on the age, geochemistry, and environmental impact of High Arctic Large Igneous Province magmatism: tracing the extension of the Alpha Ridge onto Ellesmere Island, Canada |
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| Auteur | Naber, T V; Grasby, S E ; Cuthbertson, J P; Rayner, N; Tegner, C |
| Source | Geological Society of America Bulletin 2020 p. 1-17, https://doi.org/10.1130/B35792.1  Accès ouvert |
| Année | 2020 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20200346 |
| Éditeur | Geological Society of America |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1130/B35792.1 |
| Media | papier; en ligne; numérique |
| Formats | pdf; xlsx (Microsoft® Excel®) |
| Province | Nunavut |
| SNRC | 340F/07; 340F/08; 340F/09; 340F/10 |
| Région | Hansen Point; île d'Ellesmere; Canadian Arctic Archipelago; Petersen Bay; Océan Arctique |
| Lat/Long OENS | -83.0000 -81.0000 82.6667 82.3333 |
| Sujets | marges continentales; antécédents tectoniques; magmatisme; mise en place; cristallisation; échantillons globaux; analyses géochimiques; géochimie des éléments en trace; géochimie des éléments majeurs;
analyses minéralogiques; pétrographie; datation radiométrique; datation au uranium-plomb; interprétations géophysiques; interprétations magnétiques; anomalies magnétiques; géologie du substratum rocheux; lithologie; roches ignées; tholéiites;
dolérites; roches volcaniques; basaltes; rhyolites; andésites; dacites; roches intrusives; syenites; intrusions; filons rocheux; corrélation; nomenclature; stratotypes; Formation de Strand Fiord ; Bassin de Franklin ; Bassin de Sverdrup ;
géochronologie; géochimie; minéralogie; tectonique; Nature et environnement; Sciences et technologie; Phanérozoïque; Mésozoïque; Crétacé |
| Illustrations | cartes de localisation; cartes géolscientiques généralisées; coupes stratigraphiques transversales; échelles stratigraphiques; corrélations stratigraphiques; photographies; graphiques; tableaux;
photomicrographies; diagrammes Concordia |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Terrane Pearya, Ellesmere nord de l'ouest de l'Arctique |
| Diffusé | 2020 12 16 |
| Résumé | (disponible en anglais seulement)
The High Arctic Large Igneous Province (HALIP) represents extensive Cretaceous magmatism throughout the circum-Arctic borderlands and within the Arctic Ocean
(e.g., the Alpha-Mendeleev Ridge). Recent aeromagnetic data shows anomalies that extend from the Alpha Ridge onto the northern coast of Ellesmere Island, Nunavut, Canada. To test this linkage we present new bulk rock major and trace element
geochemistry, and mineral compositions for clinopyroxene, plagioclase, and olivine of basaltic dykes and sheets and rhyolitic lavas for the stratotype section at Hansen Point, which coincides geographically with the magnetic anomaly at northern
Ellesmere Island. New U-Pb chronology is also presented.
The basaltic and basaltic-andesite dykes and sheets at Hansen Point are all evolved with 5.5-2.5 wt% MgO, 48.3-57.0 wt% SiO2, and have light rare-earth element enriched patterns. They
classify as tholeiites and in Th/Yb vs. Nb/Yb space they define a trend extending from the mantle array toward upper continental crust. This trend, also including a rhyolite lava, can be modeled successfully by assimilation and fractional
crystallization. The U-Pb data for a dacite sample, that is cut by basaltic dykes at Hansen Point, yields a crystallization age of 95.5 ± 1.0 Ma, and also shows crustal inheritance. The chronology and the geochemistry of the Hansen Point samples are
correlative with the basaltic lavas, sills, and dykes of the Strand Fiord Formation on Axel Heiberg Island, Nunavut, Canada. In contrast, a new U-Pb age for an alkaline syenite at Audhild Bay is significantly younger at 79.5 ± 0.5 Ma, and correlative
to alkaline basalts and rhyolites from other locations of northern Ellesmere Island (Audhild Bay, Philips Inlet, and Yelverton Bay West; 83-73 Ma). We propose these volcanic occurrences be referred to collectively as the Audhild Bay alkaline suite
(ABAS). In this revised nomenclature, the rocks of Hansen Point stratotype and other tholeiitic rocks are ascribed to the Hansen Point tholeiitic suite (HPTS) that was emplaced at 97-93 Ma. We suggest this subdivision into suites replace the
collective term Hansen Point volcanic complex.
The few dredge samples of alkali basalt available from the top of the Alpha Ridge are akin to ABAS in terms of geochemistry. Our revised dates also suggest that the HPTS and Strand Fiord Formation
volcanic rocks may be the hypothesized subaerial large igneous province eruption that drove the Cretaceous Ocean Anoxic Event 2. |
| Sommaire | (Résumé en langage clair et simple, non publié)
L'article présente de nouvelles données et interprétations sur la géochimie et l'âge des roches volcaniques du Crétacé exposées sur la pointe
Hansen, sur l'île d'Ellesmere, au Nunavut, dans le Haut-Arctique canadien. La géochimie et l'âge de ces roches volcaniques sont comparés à ceux d'autres parties de la grande province ignée de l'extrême Arctique, y compris la chaîne Alpha. Ces
informations contribuent aux recherches nécessaires pour définir les limites territoriales dans les eaux internationales. |
| GEOSCAN ID | 327034 |
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