Gold mineralization in the Archean Wawa Gold Corridor, Wawa, Ontario
Bibliographic record
Abstract
The Wawa Gold Corridor (WGC), located in the Michipicoten greenstone belt, comprises Au-bearing shear zones that crosscut the 2.75 Ga Jubilee Stock. Shear zones formed during protracted deformation (D1 – D3) and contain Au mineralization produced by two major events. The first comprises syn-deformation gold with arsenopyrite and pyrite in D1 – D2 schists and the second comprises post-deformation gold with Bi-Te minerals, chalcopyrite, and pyrite in carbonate ± riebeckite alteration rims around pyrite in D3 shear veins. Observations of porosity and inclusions in D1 arsenopyrite and D2 pyrite suggest that these sulfides underwent coupled dissolution-precipitation reactions (CDR). Based on trace-element analysis by laser-ablation inductively-coupled plasma mass spectrometry, it is evident that the replacement of Au-rich minerals by Au-poor minerals during CDR generated native gold from Au previously in solid-solution. Textural relationships amongst gold and Bi-Te minerals are consistent with precipitation from a Bi-rich polymetallic melt during the second gold event. The rare presence of riebeckite in the siderite-rich coronae that host Au-Bi-Te assemblages suggests that this event was associated with the emplacement of 1.0 Ga lamprophyre dikes. However, overlap in the δ34S values of pyrite in this event (0.4 – 2.4 ‰) with those of earlier pyrite (0.1 – 4.1 ‰) indicate recycling of pre-existing sulfide sulfur during the 1.0 Ga hydrothermal overprint. By comparing the Au contents of arsenopyrite (10s – 1,000s of ppm) to those of pyrite (<0.01 – 10s of ppm), it is determined that despite the textural and temporal variance with which gold occurs, almost all of the gold in the system originated as solid-solution Au in D1 arsenopyrite. This work therefore highlights the importance of discriminating between the introduction of new Au and the redistribution of existing Au within a deposit, an intricacy that can be resolved using mineral-chemical analysis and mass-balance calculations.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 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".