Chemical imprint of highly metamorphosed volcanic-hosted hydrothermal alterations in the La Romaine Supracrustal Belt, eastern Grenville Province, Quebec
Bibliographic record
Abstract
The La Romaine Supracrustal Belt and the southeastern end of the Wakeham Group in the eastern Grenville Province, Canada, host a series of Pinwarian, 1.50 Ga felsic-dominated volcanic centres metamorphosed at amphibolite to granulite facies during the Grenville orogeny. The centres are interpreted as being related to the emergence of rhyolitic domes in shallow-marine intra-arc basins within the active Pinwarian continental magmatic arc. High-grade metamorphosed hydrothermal alteration zones are intimately associated with pyroclastic deposits composing these volcanic centres and an overlying composite amphibolite unit. They comprise layers of rhyolitic metatuff bearing networks of aluminous nodules and veins, migmatized garnetbiotitesillimanite gneiss with well-preserved volcanic fragments, and mottled quartzcordierite gneiss with textures similar to those of vuggy silica facies. Alteration zones of ironstone, carbonate and calc-silicate rocks, garnetite, diopsidite, epidosite, and sulphide mineralization collectively cut across the internal contacts of a composite amphibolite unit inferred to be a mafic lava and sill complex. Lithogeochemical analysis of inferred metamorphosed altered rocks and precursors highlights chemical changes typical of metamorphosed sericitic zones, advanced argillic and silicic zones, and discharge zones characterized by calcic alterations and copper mineralizations. Such zones involve the interaction of hot, very acidic to neutral fluids. Medium to heavy rare-earth elements (REE) and Zr behave as mobile elements in the hydrothermal system as a result of the presence of F-rich fluids. The chemical changes recorded by the various alteration zones share similarities with those observed in high-sulphidation, volcanic-hosted massive sulphide deposits occurring in proximal, shallow-marine, volcanic sequences.
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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 | 0.001 | 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) | 0.003 | 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".