The escoumins supracrustal belt: a record of Mesoproterozoic (Pinwarian) evolution of the Laurentian margin and Grenvillian magmatism, central Grenville Province, Quebec, Canada
Bibliographic record
Abstract
The Mesoproterozoic, Pinwarian-age (1.52 – 1.46 Ga) Escoumins supracrustal belt (southern central Grenville Province, Quebec) consists of a volcano-sedimentary sequence (Saint-Siméon Group) and its structural basement (Tadoussac Intrusive Suite), both deformed and metamorphosed to the amphibolite-facies during the Grenvillian orogeny (1.09 – 0.98 Ga). It represents preserved parts of an island arc built on crustal slivers rifted away from the southeastern Laurentian margin during a major Geon 15 extensional event. Change in arc dynamics led to the closure of the previously opened seaway and back-arc basins and to the final accretion of the island arc at about 1.39 Ga, as marked by the emplacement of a major 1.43 – 1.37 Ga arc-related plutonic belt. The Saint-Siméon Group is an oceanic island arc, rifted-arc and back-arc volcano-sedimentary succession that despite deformation and metamorphism, preserves well original characteristics of the rocks. Its middle member (Moulin-à-Baude Formation) consists of highly evolved alkaline felsic to intermediate volcanic rocks and ferrobasalt together with island arc tholeiite, back-arc basalt and arc basaltic andesite interpreted to reflect the rifting of the arc. Some rocks were extensively altered by synvolcanic hydrothermal fluids and show mineral assemblages typical of metamorphosed VMS-type deposits. The supracrustal belt represents higher crustal levels of the orogenic infrastructure in the Grenville and was intruded by diverse types of syn-to late-orogenic plutons: (1) ca. 1.08 Ga crust-derived magnesian felsic magmatism at the onset of the continental collision, (2) ca. 1.06 – 1.04 Ga ferroan and Ba – Sr enriched intermediate to felsic plutons fractionated from a mafic magma derived from partial melting of a Geon 14 subduction-modified subcontinental lithospheric mantle coeval with amphibolite-facies metamorphism in the supracrustal rocks, and (3) ca. 0.99 – 0.98 Ga crust-derived peraluminous two-mica leucogranite bodies and pegmatite coeval with titanite growth and deformation. Despite the deformation and the metamorphic overprint, primary features are still preserved providing key information about the evolution of the southeastern Laurentian margin before the final continental collision. This study represents one of the first complete investigations of a polydeformed and metamorphosed volcano-sedimentary sequence and of its hydrothermal alteration assemblages within the Grenville Province.
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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 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| 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".