The age of salinic deformation constrained by <sup>40</sup> Ar/ <sup>39</sup> Ar dating of multiple cleavage domains: Bathurst Supergroup, New Brunswick Appalachians
Bibliographic record
Abstract
In the New Brunswick Appalachians, polydeformed felsic volcanic rocks of the Bathurst Supergroup record four cleavage-forming tectonic events, of which D~1~ and D~2~ record subduction-related underplating of buoyant elements of the Tetagouche backarc basin and subsequent collision between composite Laurentia and the Gander margin, respectively, during the Salinic orogenic cycle. Here we present an integrated approach to dating multiple cleavage domains in which we performed step heat ^40^Ar/^39^Ar analyses, microstructural observations and mineral-chemistry analysis on a suite of samples, as well as *in situ*^40^Ar/^39^Ar analysis on two samples from the suite with clear S~1~ and S~2~ cleavage relationships. We use this dataset to characterize the complex relationships between S~1~ and S~2~ white mica between samples at different structural settings across the supergroup. We refine the timing of S~1~ white mica growth, and hence M~1~-D~1~ of the Salinic cycle in the Bathurst Supergroup to *ca.* 452 to 437 Ma, and S~2~ white mica growth (also D~2~) to *ca.* 427 to 418 Ma. New and published data indicate local thermal resetting of white mica at *ca.* 411 Ma, which we interpret to indicate a buried intrusion, likely a component of the Central plutonic belt. Delineation of the two white mica age components, particularly within a single sample, was informed by both spatially-controlled analysis (*in situ*^40^Ar/^39^Ar), and the higher age precision of step heat ^40^Ar/^39^Ar analyses.
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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 | 0.001 |
| 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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".