The Canadian Malartic deposit: an example of oxidized, intrusion-related gold mineralization in the Abitibi greenstone belt, Québec, Canada
Bibliographic record
Abstract
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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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.004 |
| Science and technology studies | 0.004 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".