Controls on gold mineralization at the Onaman prospect, northwestern Ontario
Bibliographic record
Abstract
The Onaman property in northwestern Ontario hosts several unusual mesothermal gold occurrences, in which gold is associated with chalcopyrite. This study examines two showings with contrasting mineralization styles. The Ryne showing is underlain by intermediate to felsic metavolcaniclastic rocks, and features a brittle-ductile shear zone with disseminated low-grade gold mineralization, whereas the Hourglass showing contains high concentrations of gold disseminated in narrow felsic dykes. Mineralization proceeded with an initial stage of pyritization, which decreased aH2S and fO 2 of the fluid, while coeval carbonatization decreased the pH. These changes in physico-chemical parameters lead to the second mineralization stage, in which pyrite was replaced by arsenopyrite and pyrrhotite. Chalcopyrite and gold co-precipitated and both replaced pyrite. The decrease in aH2S, which reduced Au(HS)2- and Cu(HS)2- stabilities, was the principal control of gold and chalcopyrite deposition. The absence of copper in most mesothermal deposits is explained by the extreme solubility of this metal as a bisulfide complex, which prevents its precipitation as chalcopyrite. The rare occurrence of chalcopyrite at Onaman reflects unusually low solubility of copper due to the combined effects of an abnormally low initial pH of the fluid and a low fluid/rock ratio.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".