Petrogenesis of Siluro-Devonian rhyolites of the Tobique Group in the northwestern Appalachians (northern New Brunswick, Canada): tectonic implications for the accretion history of peri-Gondwanan terranes along the Laurentian margin
Bibliographic record
Abstract
Abstract Uppermost Silurian–Lower Devonian felsic rocks in the bimodal volcanic suite of the Tobique Group in the northwestern mainland Appalachians (northern New Brunswick, Canada) form part of an overstep sequence deposited across the accreted vestiges of Iapetus Ocean on composite Laurentia. Whereas the mafic rocks of the bimodal volcanic suite are continental tholeiites, the felsic rocks are peraluminous and possess geochemical characteristics of A2-type granites emplaced in post-collisional extensional settings. The major and trace element compositions of the felsic rocks indicate that they were generated by dehydration melting of late Precambrian granitoid rocks triggered by heat derived from the rising mafic magma. Unlike the basalts, which have positive ε Nd ( t ) values, the felsic rocks have values close to chondrites (−1.6 to +1.1), which is consistent with derivation from a crustal source. The rapid transition from compressional to extensional magmatism in latest Silurian–Early Devonian times in this part of Ganderia is probably due to Late Silurian Ganderia–Laurentia collision followed by slab breakoff. Based on Sm–Nd isotopic characteristics in their respective igneous rocks, both Ganderia and Avalonia are underlain by similar Neoproterozoic lower–middle crust and subcontinental lithospheric mantle.
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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 | 0.003 | 0.002 |
| 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) | 0.002 | 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".