Tectonic evolution of high-grade metamorphic tectonites of the Meelpaeg structure near Port aux Basques, southwestern Newfoundland during the Silurian Salinic and Early-to-Middle Devonian Acadian orogenies
Bibliographic record
Abstract
The Meelpaeg structure in southwestern Newfoundland comprises allochthonous tectonites formed during the Salinic (D1-2) and Acadian (D3) orogenies. D1-2 occurred between 451 and 417 Ma and culminated in Barrovian metamorphism during terminal collision of the Gander margin with composite Laurentia. Collision was followed by tectonic escape of the deeply buried rocks between 417 and 412 Ma. Rocks of the Victoria arc and Exploits backarc preserved in the Port aux Basques and Grand Bay complexes were emplaced during D1 by the Grandys River shear zone, which is outlined by a narrow band of the ca. 451 Ma Port aux Basques granite, towards the southeast above the Harbour le Cou Group. The contrasting histories displayed across the Grandys River shear zone are typical of the Dog Bay Line further northeast. Salinic structures were overprinted by faults and folds formed during Acadian D3 transpression (≤412 Ma), which produced the bi-vergent Meelpaeg structure and emplacement of amphibolite facies tectonites above greenschist facies rocks along its bounding shear zones. F3 folding progressively steepened the faults, which in turn led to progressive localization of dextral strike–slip in narrow fault zones. The high grade of metamorphism in the Meelpaeg structure is attributed to protracted underthrusting of the Cabot promontory of the Gander margin beneath composite Laurentia. Salinic convergence was sinistral but became dextral during the Early Devonian, diachronous Acadian orogeny. The kinematic switch is proposed as a tool to separate Salinic from Acadian structures in the central part of the northern Appalachians.
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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 | 0.001 | 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) | 0.003 | 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".