| Titre | Evidence for a Neoarchean to earliest-Paleoproterozoic mantle metasomatic event prior to formation of the Mesoproterozoic-age Strange Lake REE deposit, Newfoundland and Labrador, and Quebec,
Canada |
| Télécharger | Téléchargements |
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| Licence | Veuillez noter que la Licence du gouvernement
ouvert - Canada remplace toutes les licences antérieures. |
| Auteur | Mohammadi, N; Corrigan, D ; Sappin, A -A; Rayner, N |
| Source | Commission géologique du Canada, Présentation scientifique 143, 2022, 23p., https://doi.org/10.4095/330866  Accès ouvert |
| Image |  |
| Année | 2022 |
| Éditeur | Ressources naturelles Canada |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.4095/330866 |
| Media | numérique; en ligne |
| Formats | pdf |
| Province | Terre-Neuve-et-Labrador; Québec |
| SNRC | 24A; 24B; 24G; 24H |
| Région | Strange Lake |
| Lat/Long OENS | -68.0000 -64.0000 58.0000 56.0000 |
| Sujets | manteau terrestre; gisements métasomatiques; terres rares; Archéen; Province de Churchill ; géochimie; Protérozoïque; Précambrien |
| Illustrations | photographies; cartes de localisation; diagrammes schématiques; graphiques; photomicrographies |
| Programme | Initiative géoscientifique ciblée (IGC-6) Systèmes minéralisés |
| Diffusé | 2022 10 12 |
| Résumé | (disponible en anglais seulement)
A complete suite of bulk major- and trace-elements measurements combined with macroscopic/microscopic observations and mineralogy guided by scanning electron
microscope-energy dispersive spectrometry (SEM-EDS) analyses were applied on Nekuashu (2.55 Ga) and Pelland (2.32 Ga) intrusions in northern Canada, near the Strange Lake rare earth elements (REE) deposit, to evaluate their magmatic evolution and
possible relations to the Mesoproterozoic Strange Lake Peralkaline Complex (SLPC). These Neoarchean to earliest-Paleoproterozoic intrusions, part of the Core Zone in southeastern Churchill Province, comprise mainly hypersolvus suites, including
hornblendite, gabbro, monzogabbro/monzodiorite, monzonite, syenite/augite-syenite, granodiorite, and mafic diabase/dyke. However, the linkage of the suites and their petrogenesis are poorly understood. Geochemical evidence suggests a combination of
'intra-crustal multi-stage differentiation', mainly controlled by fractional crystallization (to generate mafic to felsic suites), and 'accumulation' (to form hornblendite suite) was involved in the evolution history of this system. Our model
proposes that hornblendite and mafic to felsic intrusive rocks of both intrusions share a similar basaltic parent magma, generated from melting of a hydrous metasomatized mantle source that triggered an initial REE and incompatible element enrichment
that prepared the ground for the subsequent enrichment in the SLPC. Geochemical signature of the hornblendite suite is consistent with a cumulate origin and its formation during the early stages of the magma evolution, however, the remaining suites
were mainly controlled by 'continued fractional crystallization' processes, producing more evolved suites: gabbronorite/hornblende-gabbro ? monzogabbro/monzodiorite ? monzonite ? syenite/augite-syenite. In this proposed model, the hydrous
mantle-derived basaltic magma was partly solidified to form the mafic suites (gabbronorite/hornblende-gabbro) by early-stage plagioclase-pyroxene-amphibole fractionation in the deep crust while settling of the early crystallized hornblende
(+pyroxene) led to the formation of the hornblendite cumulates. The subsequent fractionation of plagioclase, pyroxene, and amphibole from the residual melt produced the more intermediate suites of monzogabbro/monzodiorite. The evolved magma ascended
upward into the shallow crust to form monzonite by K-feldspar fractionation. The residual melt then intruded at shallower depth to form syenite/augite-syenite with abundant microcline crystals. The granodiorite suite was probably generated from lower
crustal melts associated with the mafic end members. Later mafic diabase/dykes were likely generated by further partial melting of the same source at depth that were injected into the other suites. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Dans le cadre de cette étude, nous avons examiné deux complexes plutoniques du nord du Canada (les intrusions Nekuashu et Pelland) et leur
association possible avec le gisement bien connu de Strange Lake, l'un des gisements de métaux rares les plus riches au monde. Les données chimiques et géochronologiques combinées ont démontré que les intrusions Nekuashu et Pelland ont été formées
suite à la fonte partielle d'une source mantellique métasomatisée et hydratée qui a conduit à un enrichissement initial en éléments des terres rares (ETR) et en éléments incompatibles préparant ainsi le terrain pour l'enrichissement ultérieur dans le
gisement de Strange Lake. De plus, nous avons démontré que ces deux intrusions présentaient également un potentiel intéressant pour l'exploration des ETR dans cette région. |
| GEOSCAN ID | 330866 |
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