A Late Silurian (Pridolian) age for the Eastport Formation, Maine: a review of the fossil, stratigraphic, and radiometric-age data
Bibliographic record
Abstract
The Eastport Formation is part of a larger volcaniclastic sequence (the Coastal Volcanic Belt) that extends from Massachusetts, USA, into New Brunswick, Canada. It represents a portion of Avalonia that was accreted to Laurentia during the Acadian orogeny. For more than thirty years the age of this formation has been regarded as Early Devonian (Lochkovian or Pragian) based on a new and yet undescribed ostracode genus. However, careful analysis of the fossil data indicates a Late Silurian (Pridolian) age for the fauna, and shows that the evidence used to assign a Devonian age should have been regarded as provisional. This interpretation is additionally strengthened by local stratigraphy and recent radiometric dating, both of which support a Late Silurian age for the Eastport Formation. RÉSUMÉ La Formation d'Eastport fait partie d'une séquence volcanoclastique plus importante (ceinture volcanique Côtière) qui s'étend du Massachusetts, aux États-Unis, jusqu'à l'intérieur du Nouveau-Brunswick, au Canada. Elle représente une partie du continent avalonien qui s'était accrétionné au continent laurentien pendant l'orogenèse acadienne. Pendant plus d'une trentaine d'années, on a considéré que cette formation remontait au Dévonien précoce (Lochkovien ou Praguien) en se basant sur un nouveau genre d'ostracode encore non décrit. Une analyse attentive des données relatives au fossile révèle toutefois que la faune remonte au Silurien tardif (Pridolien) et montre que les observations utilisées pour l'attribution d'un âge dévonien auraient dû être considérées comme provisoires. Cette interprétation se trouve par ailleurs renforcée par la stratigraphie locale et une datation isotopique récente, qui appuient toutes deux la datation de la Formation d'Eastport à l'époque du Silurien tardif. [Traduit par la rédaction.]
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.006 | 0.004 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".