Stratigraphy and geochemistry of the Lac-Brompton ophiolite, Canada: evidence for extensive forearc magmatism and mantle exhumation in the Southern Quebec Ophiolite Belt
Bibliographic record
Abstract
Three ophiolites are currently recognized in the southern Quebec Appalachians, from south to north: the Mont-Orford ophiolite, dominated by tholeiitic to transitional–alkaline basalt and diabase, and the Thetford Mines and Asbestos ophiolites, which are made up of boninites and tholeiitic basalts. This contribution documents the origin, geochemistry, and geodynamic evolution of the Lac-Brompton ophiolite, which was previously interpreted as a diapiric serpentinite mélange and genetically attributed to the Mont-Orford ophiolite. Our study of its igneous rocks rather indicates that the Lac-Brompton ophiolite is an exhumed segment of oceanic lithosphere represented by mantle rocks of harzburgitic composition and a discontinuous crust made up of boninitic volcanic rocks and intrusions of gabbro, pyroxenite, and granitoids that, respectively, overlie and crosscut the harzburgite. The ophiolitic mantle and crustal rocks and underlying infra-ophiolitic tectonic sole are overlain by sedimentary rocks belonging to the Saint-Daniel Mélange. The internal stratigraphy of the ophiolite and relationships with the Saint-Daniel Mélange suggest that the mantle rocks were exhumed to seafloor level prior to boninitic magmatism, and that the mantle and crustal rocks were deeply eroded during or shortly after obduction. The intra-oceanic evolution of the Lac-Brompton ophiolite is believed to have been comparable to the one of ultramafic core complexes exposed along slow-spreading ridge segments. The stratigraphic and geochemical characteristics of the Lac-Brompton ophiolite suggest that it forms, with the Asbestos and Thetford Mines ophiolites, a composite slab of forearc seafloor.
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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 | 0.002 |
| Science and technology studies | 0.002 | 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) | 0.002 | 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".