The Uplift of Armorica and the Bretonian Movements of the Variscan Orogeny‐New Insights From Detrital Zircons in the Early Carboniferous Terrigenous Rocks of the Laval Basin (Armorican Massif, France)
Bibliographic record
Abstract
Abstract In the French Armorican Massif, the Bretonian phase of the Variscan orogeny has been defined by the Late Devonian (Famennian‐Frasnian) erosion gap, and the Early Carboniferous (Tournaisian) syntectonic terrigenous deposits of the l’Huisserie formation in the Laval basin in the Central‐North Armorican Domain, ascribed to the Armorica microcontinent. This phase is coeval with vertical (epeirogenic) movements. In addition to Neo‐, and Paleo‐Proterozoic peaks, ascribed to the Cadomian and Icartian events, respectively, the detrital zircon age populations of the l’Huisserie formation reveal the existence of a 388–358 Ma magmatic event previously recognized by the ca 367–360 Ma dolerite dyke swarms exposed in the N. part of the Central‐North Armorican Domain. The isotopic (εHf) signature of these grains documents a pre‐orogenic Variscan mantle contribution for the mafic magmatism interpreted here as the indication of the south‐directed subduction of the Le Conquet‐Teplá ocean, that is, a branch of the Rheic ocean, below the Armorica microcontinent during the Bretonian phase. The intraplate opening of the Laval, Ménez‐Bélair, and Châteaulin basins was coeval with this subduction. In the Laval area, the final closure of the basin, accommodated by north‐directed folds‐and‐thrusts, took place after the Bashkirian (ca 320 Ma).
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".