| Titre | Petrography, geochemistry and geochronology of the REE-mineralized Fox Harbour Volcanic Belt, southeastern Labrador |
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| Auteur | Magyarosi, Z; Rayner, N |
| Source | Newfoundland and Labrador Department of Industry, Energy and Technology, Geological Survey, Current Research 23-1, 2023 p. 1-29 |
| Liens | Online - En ligne
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| Image |  |
| Année | 2023 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20220619 |
| Éditeur | Newfoundland and Labrador Department of Industry, Energy and Technology |
| Document | publication en série |
| Lang. | anglais |
| Media | papier; numérique; en ligne |
| Formats | pdf |
| Province | Terre-Neuve-et-Labrador |
| SNRC | 13A; 13B/01; 13B/02; 13B/07; 13B/08; 13B/09; 13B/10; 13B/15; 13B/16; 13G/01; 13G/02; 13G/07; 13G/08; 13G/09; 13G/10; 13G/15; 13G/16; 13H |
| Région | Fox Harbour; Port Hope Simpson; St. Lewis |
| Lat/Long OENS | -59.0000 -56.0000 54.0000 52.0000 |
| Sujets | analyses de la roche, éléments de terres rares; terres rares; pétrographie; alcalinité; Province de Grenville; géochimie; géochronologie; minéralogie; Protérozoïque |
| Illustrations | cartes de localisation; tableaux; croquis géologiques; photomicrographies; graphiques |
| Programme | Initiative géoscientifique ciblée (IGC-6) Systèmes minéralisés |
| Diffusé | 2023 03 11 |
| Résumé | (disponible en anglais seulement)
The Fox Harbour Volcanic Belt (FHVB) in the Grenville Province of southeastern Labrador is one of several Mesoproterozoic peralkaline complexes hosting
rareearthelement (REE) mineralization, such as the Strange Lake and Flowers River complexes, and the Red Wine Intrusive Suite. The FHVB is ~64 km long, ranging in thickness from 50 m in the east to 3 km in the west, and contains three mineralized
belts running parallel to each other. The main rock types are peralkaline volcanic rocks (pantellerite, comendite, and pantelleritic and comenditic trachyte), which host the REE mineralization, nonperalkaline rhyolite and mafic volcanic rocks. The
main minerals in the pantellerite and comendite are quartz, Kfeldspar, albite, allanite, magnetite, zircon, titanite and less than 10% biotite and calcic-sodic amphibole and/or pyroxene. Pantelleritic and comenditic trachyte are composed of albite,
~30% calcic-sodic pyroxene and amphibole, biotite, Kfeldspar, zircon and allanite. The REE minerals identified in this study include allanite, fergusonite, locally REEtitanite, rare britholite and two unidentified phases. They crystallized late and
occur with zircon, magnetite, titanite, local apatite and mafic minerals. Geochronology of four samples from the Deep Fox deposit in the eastern part of the FHVB indicate that the rocks crystallized ca. 1300 Ma and were subjected to Grenvillian
metamorphism ca. 1050 Ma. Nonperalkaline rhyolite returned an igneous crystallization age of 1269 ± 9.5 Ma overprinted by a metamorphic age of 1031 ± 15 Ma. Comendite returned an igneous crystallization age of 1314 ± 12 Ma and pantellerite returned a
metamorphic age of 1065 ± 8.2 Ma. A sample from a leucogabbro located north of the FHVB returned an igneous crystallization age of ca. 1300 Ma overprinted by a metamorphic age of 1038 } 29 Ma. The FHVB is bimodal. The felsic rocks are peralkaline to
metaluminous, Atype rhyolites and trachytes. Mineralization is hosted in the most strongly fractionated rocks characterized by the highest REE, highfieldstrength element (HFSE: Zr, Hf, U, Th) and Fe contents, with the Zr content up to 26 361 ppm. The
lightrareearth element (LREE) and heavyrareearth element (HREE) enrichments are 100 to 20 000 times higher and 10 to 1000 times higher than the chondrite concentrations, respectively. The east FHVB (EFHVB) has higher concentrations of LREEs than the
west FHVB (WFHVB), similar concentrations of HREEs, but the HREE/LREE ratio is higher in the WFHVB. Parts of the FHVB underwent Na loss and K metasomatism resulting in their apparent metaluminous nature. The results of this study highlight the
complex evolution (magmatic, hydrothermal and metamorphic) of the FHVB and associated REE mineralization and challenges some aspects of the current models for this type of deposit, such as the lack of significant REE mineralization in peralkaline
extrusive rocks and the increase in degree of fractionation over time. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Ce rapport résume la pétrographie, la géochimie et la géochronologie des roches de la ceinture volcanique de Fox Harbour dans la région de Port
Hope Simpson - St. Lewis, au sud-est du Labrador, associées à une minéralisation d'éléments de terres rares (ETR). Il fait partie d'un projet pluriannuel financé par la Commission géologique de Terre-Neuve-et-Labrador (GSNL) et la Commission
géologique du Canada (CGC) dans le cadre du programme de l'Initiative géoscientifique ciblée (IGC). |
| GEOSCAN ID | 331531 |
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