"CAGE": a new uranium province, Nunavik, Quebec
Notice bibliographique
Résumé
The CAGE district was discovered during an exploration survey made in 2005 in Northern Québec, by Claude Caillat (AREVA) and Serge Genest (Omegalpha). The district is located in the northeastern Canadian Shield, at the eastern margin of Ungava Bay. The U showings are located in Paleoproterozoic metasedimentary rocks (Lake Harbour Group) that were deposited on a passive margin epicontinental platform setting. High-grade metamorphism with partial melting occurred during the Torngat collision (1.86–1.74 Ga). Several pegmatoid generations were injected into the metasedimentary rocks. The strongly differing structural, mineralogical and geochemical characteristics of each generation reflect derivation by partial melting from a variety of protoliths. The pegmatoid bodies are generally poorly mineralized in U, except for some located outside the CAGE district (e.g., Amaujaq). Two types of mineralization have been distinguished according to their geological setting, mineralogical, and geochemical characteristics, but both give the same age on uraninite (1790 ± 10 Ma). The first type is hosted by impure dolomitic marble (with phlogopite – olivine – K-feldspar) and skarnoids (diopside – tremolite – phlogopite – K-feldspar – scapolite), resulting from nearly isochemical metamorphism of impure dolomitic limestone or marl. The ore mineral is pure uraninite with REE patterns characterized by a decreasing fractionation from the LREE to HREE, with neutral or a slightly positive Eu anomaly and a low total REE. The uraninite is consistently associated with enriched Ba (Ba-rich K-feldspar and phlogopite, celsiane, kampfite, baryte), V (coulsonite Fe++V+++2O4, V-pyroxene), Zn(sphalerite), Pb (non-radiogenic galena), S-Cu (pyrite, pyrrhotite, chalcopyrite, chalcosite), As (arsenopyrite), Sb (ullmannite NiSSb) and Mo (molybdenite). The scapolite composition (40 < marialite % < 60) and kampfite [Ba12(Si11Al5)O31(CO3)8Cl5] suggest the influence of evaporitic fluids. Graphite is locally observed in the marble. Organic matter and/or sulphide minerals may have represented the initial U traps. The uraninite could have been present in the marble prior to metamorphism or it may have been introduced during metamorphism. The second type of U mineralization is hosted by calc-silicate rocks (skarnoids or primary skarns) located in the vicinity of pegmatoid injections in transtensional settings. The endoskarns are dominated by scapolite and the exoskarns by Fe-rich diopside. Newly formed tremolite, scapolite (20 < Marialite % < 70), phlogopite, and calcite in veins and vugs are spatially associated. The ore minerals are Th-rich uraninite and uranothorianite, characterized by high REE contents, a weak global fractionation, and a marked Eu anomaly. These are typical of magmatic uraninite, in particular that of the Rössing alaskite. Both uranium enrichment and the late vein minerals are seemingly related to expulsion of magmatic fluid from the latest pegmatites. This event corresponds to transtension near the end of the tectonic-magmatic cycle, also typical of the Rössing setting. U-enrichment in the CAGE province is interpreted to have started with the emplacement of U-rich high-K Archean granite in the basement. During the Paleoproterozoic, U was leached from the Archean granite and trapped in the reduced epicontinental platform sedimentary rocks. Partial melting of the metasedimentary rocks and possibly of the basement gneiss led to the formation of U-rich anatectic melts and fluids which were trapped in overlying marble, forming the second type of mineralization. The first type of mineralization may be of sedimentary or diagenetic origin with local remobilization by metamorphic fluids.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,002 |
| Études des sciences et des technologies | 0,005 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,008 | 0,001 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».