Volcanology, geochemistry and petrogenesis of the Expo-Raglan magmatic system in the eastern Cape Smith Belt, Nunavik, northern Quebec
Bibliographic record
Abstract
The Paleoproterozoic volcano-sedimentary Cape Smith Belt in Nunavik (northern Quebec) contains a variety of mafic-ultramafic units classifiable by position in sequence, geometry, lithology, degree of differentiation and mineralization style. Non-differentiated to differentiated mafic flows/sills comprise the majority of the section as essentially non-mineralized massive-pillowed basalts, conformable gabbroic units and differentiated pyroxenite/gabbro/basalt flows. Differentiated mafic-ultramafic sills intrude sedimentary strata of the lower and upper Povungnituk Group and host reef-style PGE-(Cu)-(Ni) mineralization (e.g. Delta). Poorly differentiated ultramafic-mafic bladed dykes along the Expo Trend in the Povungnituk Group commonly host Cu-Ni-(PGE) sulphides along their margins (e.g. Expo-Ungava, Méquillon) and reach up to 35 weight % MgO in the most magnesian olivine pyroxenitic parts and up to 16 weight % MgO in their chilled melanogabbroic margins. Poorly differentiated ultramafic lava channels along the Raglan Trend at the base of the Chukotat Group host Ni-Cu-(PGE) mineralization at or near their lower contacts, and reach MgO contents of nearly 44 weight % in the most magnesian peridotitic parts and up to 20 weight % in their chilled pyroxenitic margins. Recent dating indicates a temporal overlap between the Expo and Raglan parts of the system; however, field and geochemical data suggest that the Expo dykes are derived from less magnesian magmas and formed mineralization with higher Cu/Ni ratios than the lava channels in in the Raglan Trend. The Expo dykes may have fed other parts of the system, but do not appear to represent direct feeders to the mineralized lava channels in the Raglan parts.
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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 | 0.002 | 0.003 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".