Determination of alteration facies using the normative mineral alteration index: Selbaie Cu–Zn deposit, northern Abitibi greenstone belt, Canada
Bibliographic record
Abstract
The Selbaie Cu–Zn deposit is located in the northeastern portion of the northern Archean Abitibi volcanic belt. It is one of the most important base metal deposits in Canada. It includes stratiform pyrite levels in the volcanites and shallow-water sediments, stockworks in a rhyodacitic breccia, and a copper-rich vein, in a caldera context. The study of the regional alteration distribution is based on a database of more than 2300 chemical sample analyses using the NORMAT normative mineral alteration index. This method allows independent analysis of the numerous lithologic variations in the Selbaie district. Five facies are distinguished in a vast sodium-depleted zone, from the core to the periphery of the hydrothermal system: chlorite–pyrophyllite in the mineralized zones, chlorite–sericite, sericite, sericite–orthoclase and orthoclase at the periphery. The carbonates also show zoning, with ankerite–dolomite at the periphery and siderite–magnesite at the core. With NORMAT, it is possible to highlight overprinted alterations. The zoning observed at Selbaie corresponds to the overprinting of a system showing sulphide ore and acid-type epithermal deposit characteristics, with abundant pyrophyllite, very likely related to a deeper porphyritic system
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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 | 0.003 | 0.003 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".