Pinwarian (1.50 Ga) volcanism and hydrothermal activity at the eastern margin of the Wakeham Group, Grenville Province, Quebec
Bibliographic record
Abstract
Volcanic belts developed along the southeastern continental margin of Laurentia between 1.70 and 1.30 Ga and subsequently metamorphosed at high grade are today largely concealed among gneiss complexes of the Grenville Province. At the eastern end of the Wakeham Group and in the La Romaine Supracrustal Belt to the east, four 1.50 Ga volcanic centres were found among gneissic synvolcanic intrusions typical of the 1.521.46 Ga Pinwarian continental magmatic arc. Upper amphibolite- to granulite-facies rhyolitic to dacitic lavas and coarse lapillistone overlie or are intimately associated with arenites typical of the Wakeham Group. Garnetite, ironstone, carbonate rock, calc-silicate rock, and sillimanite-bearing nodules, veins, and gneiss, locally preserving lapilli, are also present. The distribution, paragenesis, and modes of most of these latter units differ from those of normal metasediments but are diagnostic of metamorphosed exhalites and hydrothermal alteration zones. In the La Romaine Supracrustal Belt, they are associated with pyroclastic horizons and a mineralized composite amphibolite unit. Volcanic textures include flow banding, wispy lapilli moulding fragmented lapilli and rounded lapilli with quartz-feldspar mosaics (filled vesicles), and in situ shattering of lapilli. These textures and the presence of advanced argillic alteration point to vesicular volcanism and hydrothermal activity in a subaerial to shallow submarine environment. Rare mafic lapilli attest to coeval mafic magmatism. The pervasive calc-alkaline signature of the eruptive and intrusive felsic to mafic rocks and their distribution are compatible with the development of 1.50 Ga intra-arc volcano-sedimentary belts stemming from the Wakeham Group basin and extending eastward within the Pinwarian continental magmatic arc.
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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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.009 | 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".