The Canadian Malartic deposit: an example of oxidized, intrusion-related gold mineralization in the Abitibi greenstone belt, Québec, Canada
Notice bibliographique
Résumé
The Canadian Malartic deposit is Canada's largest producing gold mine, with a resource of 17.6 million ounces gold, and is an example of oxidized intrusion-related gold mineralization in the Archean Abitibi greenstone belt of Québec. The deposit hosts fine-grained, disseminated native gold and subordinate gold telluride minerals, which are accompanied by pyrite and minor fine-grained chalcopyrite, galena, sphalerite, hematite, molybdenite and a suite of Ag-Pb-Bi-bearing telluride minerals. Ore minerals occur in altered wall rock and early quartz-carbonate ± albite ± biotite veins, which are commonly surrounded by alteration haloes of K-feldspar-biotite ± calcite, and later veins of quartz-pyrite-calcite ± chlorite ± muscovite ± biotite. The gold mineralization is intimately associated with potassic alteration and associated carbonitization, and involved replacement of iron-bearing minerals in wall rock by pyrite. Mass changes reflect this alteration with nearly all altered rocks gaining K, Ca and S (almost entirely as pyrite). Barium, Cd, W, Pb, As, Sb, Bi and Mo underwent large mass gains, and Ag, Te and Au underwent extremely large mass gains. There was a mass loss of copper from nearly all the altered rocks. Isotopic ratios (δ18Ofluid of +5.15 to +9.77‰, δDfluid of -52.00 to -45.00‰, δ34Sfluid of -4.45 to +3.30‰ and small, positive ∆33S values) suggest a dominantly magmatic origin for the fluid and sulfur and a small contribution of sulfur from a sedimentary source. A dominantly magmatic source for the fluid is also suggested by the compositions of fluid inclusion leachates. Stable isotope and trace element geothermometers yield a temperature of ~475°C for the gold mineralization. A model is presented in which relatively oxidized (logƒO2 ~ -19), CO2- and sulfur-rich (∑aS > 0.1), auriferous fluids were exsolved from felsic to intermediate, alkaline to sub-alkaline magmas emplaced at mid-crustal levels. These fluids rose to higher levels where they interacted with more shallowly emplaced monzodiorite intrusions and clastic Pontiac Group metasedimentary rocks, and locally with mafic to ultramafic rocks of the Piché Group. Interaction with the porphyries and Pontiac Group metasediments buffered the fluids to near neutral pH, and interaction with the Piché Group rocks to higher pH and lower ƒO2 conditions. Ore deposition resulted from pyritization of the host rocks and oxidation of the ore fluid (due to mixing with meteoric waters), which reduced a(H2S) and caused destabilization of aqueous gold bisulphide species, leading to the precipitation of native gold and telluride minerals at ~475°C.This thesis provides a detailed description of the first clearly demonstrable example of a large oxidized intrusion-related gold system in the Archean Abitibi greenstone belt of Québec, and has considerably enhanced our understanding of the genesis of deposits of the type represented by Canadian Malartic. The study will aid in the exploration for similar deposits elsewhere, which could lead to the discovery and exploitation of other world class Archean oxidized intrusion-related gold deposits.
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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 | 0,002 | 0,004 |
| Études des sciences et des technologies | 0,004 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,004 | 0,000 |
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 ».