New biostratigraphical constraints on the lower Cambrian Ratcliffe Brook Formation, southern New Brunswick, Canada, from organic-walled microfossils
Bibliographic record
Abstract
Organic-walled microfossils from the Ratcliffe Brook Formation of southern New Brunswick enable recognition of the three lowest Cambrian acritarch-based zones established in southeastern Poland and on the East European Platform. This is the first record of these zones in Avalonia. The distribution of acritarchs of the Asteridium tornatum-Comasphaeridium velvetum, Skiagia ornata-Fimbriaglomerella membranacea, andHeliosphaeridium dissimilare-Skiagia ciliosa zones leads us to propose a revised correlation of sections of the Ratcliffe Brook Formation, in which an ash bed dated at 531 Ma now predates rather than postdates an assemblage of small shelly fossils that had been previously attributed to the Watsonella crosbyi Zone. The small shelly fossils are here suggested to belong to a younger biozone as they occur with acritarchs of the Skiagia ornata- Fimbriaglomerella membranacea Zone, the base of which is currently thought to approximate in time to the global appearance of trilobites. The occurrence of acritarchs of the Heliosphaeridium dissimilare-Skiagia ciliosa Zone close to the top of the Ratcliffe Brook Formation suggests that the upper part of this formation and the overlying Glen Falls Formation are younger than previously thought and that their correlationwith strata in Newfoundland is in need of revision.Biostratigraphic constraints are currently insufficient to position the 531Maash bedwith precisionwith respect to the Watsonella crosbyi Zone in Newfoundland, but it is likely that the date is within this zone.
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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 | 0.003 | 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) | 0.004 | 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".