| Titre | Comparative geochemical and geophysical studies of volcanic rocks from the High Arctic Large Igneous Province (HALIP) and Alpha Ridge, Arctic Ocean |
| Auteur | Williamson, M C; Oakey, G N |
| Source | 2017 p. 1227, 1 pages |
| Liens | Online - En ligne (p.1227)
|
| Année | 2017 |
| Séries alt. | Secteur des sciences de la Terre, Contribution externe 20160451 |
| Éditeur | IAVCEI (International Association of Volcanology and Chemistry of the Earth's Interior) |a Portland, US (Portland, US) |
| Réunion | IAVCEI 2017 Scientific Assembly; Portland; US; août 14-18, 2017 |
| Document | publication en série |
| Lang. | anglais |
| Media | papier; en ligne; numérique |
| Formats | pdf |
| Province | Nunavut |
| SNRC | 59G; 59H; 560A; 560D; 49; 39; 340; 120 |
| Lat/Long OENS | -97.0000 -72.0000 84.0000 76.0000 |
| Sujets | basaltes; filons-couches; filons rocheux; coulées de lave; intrusions; roches ignées; anomalies magnétiques; picrites; rhyolites; géochimie des roches; assemblages de minéraux; gîtes minéralogiques;
potentiel minier; Bassin de Sverdrup ; Bassin d'Amerasia ; combustibles fossiles; géologie régional; minéraux métalliques; minéralogie; Crétacé |
| Programme | Preparation 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)
The Canadian portion of the High Arctic Large Igneous Province (HALIP), exposed on Axel Heiberg Island and northern Ellesmere Island, consists of continental
flood basalts, sills and dykes (~125-90 Ma); ferrobasaltic lava flows and associated intrusions (~92 Ma); and bimodal alkaline igneous rocks (~88-80 Ma). The HALIP magmatic event was triggered by tectonic rejuvenation of the Sverdrup Basin and the
opening of the Arctic Ocean in the Early Cretaceous. Offshore, the Alpha-Mendeleev Ridge Complex (AMRC) is a first-order physiographic and geological feature of the Amerasia Basin that is characterized by high amplitude "chaotic" magnetic anomalies
associated with large-scale regional magmatism. The approximate areal extent of the AMRC is ~1.3x106 km2, suggesting a total volume of igneous rocks of ~20x106 km3. The only dated volcanic rock sample recovered from the Alpha Ridge is ~89
Ma.
The Hansen Point Rift Volcanics (HPRV) consist of bimodal alkaline igneous rocks that were emplaced during the waning stages of the HALIP event. Previous studies have shown that lava flows consist of picritic basalt, alkali basalt,
trachyandesite, trachyte and peralkaline rhyolite erupted from central vents. Whole rock geochemical analyses acquired for this study suggest that high-MgO lava flows (8.5-13.3 wt.%) have FeO* values of 8.9-10.7 wt.%; TiO2 values of 1.2-2.4 wt.%;
are LREE-enriched (LaN/SmN: 3-5); and have low contents of HREE (e.g. Lu: 0.26-0.37). The most magnesian lava flow analysed so far is a ferropicrite with olivine (Fo84-87) and Ti-rich diopside phenocrysts set in a glassy matrix. This result is of
interest to us because ferropicrites of Phanerozoic age occur as low volume lava flows or thin dykes associated with continental flood basalt provinces. They typically show high values of MgO, FeO*, Ni and Cr; moderate values of SiO2, and low values
of Al2O3 and HREE, and are interpreted as Fe-rich melts generated from a mantle plume.
In August 2016, approximately 100 kg of volcanic rocks were successfully dredged from the Alpha Ridge during a collaborative Canada-Sweden Polar Expedition
under Canada¿s UNCLOS (United Nations Convention on Law of the Sea) Program. We present new mineralogical, geochemical and magnetic susceptibility data for the onshore HPRV and volcanic rocks dredged from the Alpha Ridge. The results highlight the
petrological significance of ferropicrites with implications for the magmatic evolution of the onshore HALIP and offshore AMRC. |
| Résumé | (Résumé en langage clair et simple, non publié)
En août 2016, environ 100 kg de roches volcaniques ont été récupérés avec succès de la chaîne Alpha, située dans l`océan Arctique, lors d¿une
expédition polaire Canada-Suède entreprise dans le cadre du Programme continental étendu du Canada. Nous présentons de nouvelles données minéralogiques, géochimiques et de susceptibilité magnétique pour les échantillons volcaniques de la chaîne
Alpha. Les résultats sont comparés avec les données obtenues pour les roches volcaniques du rift Hansen Point affleurant dans la partie nord de l'île d'Ellesmere au Nunavut. Cette étude géochimique comparative nous permet de mieux comprendre la
nature et l'origine de la chaîne Alpha, ainsi que les liens potentiels avec la Grande Province Ignée de l¿Extrême Arctique (HALIP). |
| GEOSCAN ID | 300227 |
|
|