The Matagami District, Abitibi Greenstone Belt, Canada: Volcanic Controls on Archean Volcanogenic Massive Sulfide Deposits Associated with Voluminous Felsic Volcanism
Bibliographic record
Abstract
Several volcanogenic massive sulfide (VMS) deposits have been mined in the Archean Matagami mining district (Abitibi subprovince, Quebec, Canada), but the volcanology of their host rocks has been little studied. Most VMS lenses are located along a stratigraphic marker known as the Key tuffite. Footwall rocks belong to the Watson Lake Group (tholeiitic dacite and rhyolite), whereas hanging-wall rocks belong to the Wabassee Group (tholeiitic basalt and tholeiitic to transitional andesite, with lesser tholeiitic felsic volcanic rocks). All felsic units of the South Flank are interpreted as lobe-hyaloclastite lava flows. For most felsic units, many such flows are juxtaposed and stacked. A significant proportion of the units is made up of fragmental rocks, especially at the top of the Watson Lake Group in some specific areas where the VMS deposits sit. Where hyaloclastite is well developed, conditions were favorable for subseafloor replacement-style VMS deposits, as is the case at Bracemac-McLeod, the currently producing mine. There, sheet-shaped ore lenses were emplaced under a capping unit, the massive core of a hanging-wall lobe-hyaloclastite flow. The proximal footwall chlorite alteration zone is subconcordant. Abundant hyaloclastite is also present at the 25 Mt Mattagami Lake deposit, and similar ore-forming conditions are inferred. In other places, fragmental rocks were less developed at the top of the Watson Lake rhyolite, and sulfides formed mounds on the sea floor, with a discordant chlorite pipe underneath. Therefore, several styles of VMS mineralization can be considered in a single mining district, even at a specific marker horizon, depending on the volcanic facies found in the host sequence.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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 teacher head, 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".