Late Cambrian (middle Furongian) shallow-marine dysoxic mudstone with calcrete and brachiopod–olenid–<i>Lotagnostus</i>faunas in Avalonian Cape Breton Island, Nova Scotia
Bibliographic record
Abstract
Abstract The common belief that organic-rich mudstones formed in quiescent, distal settings is further weakened by study of an upper Cambrian (Leptoplastus– lowerPelturasuperzones) succession in the Chesley Drive Group in Avalonian Cape Breton Island that is comparable to Alum Shale successions in Baltica. Dramatic sea-level (likely eustatic) changes are now recognized by punctuation of deposition of shallow, wave-influenced black mudstone with brachiopod (Orusia lenticularis) and olenid trilobite-bearing limestones by offlap and formation of a subaerially cemented calcrete-clast conglomerate. Subaerial exposure was followed by transgression and accumulation of clastic pyrite sand and phosphatic granules withLeptoplastusSuperzone (L. ovatusZone) trilobite sclerites. Dynamic processes are shown by wave ripples in the mudstone and limestone, sorting and winnowing of fossil rudstones, and pre-compactional fracture of the conglomerate and rudstones.Orusiarudstones in the succession below the conglomerate are regarded as analogues ofEoorthisandBillingsellarudstones in the ‘biomere’ extinction intervals of the Laurentian basal Sunwaptan. The lowestOrusia-rich beds are no older than theP. spinulosaZone but, as elsewhere in Avalonia, they range into the higherLeptoplastus(Cape Breton) and even thePeltura(Britain, New Brunswick) superzones. Rare agnostoid sclerites in lowerPelturaSuperzone (Ctenopyge tumidaZone) olenid rudstone resemble those traditionally assigned toLotagnostus trisectusin Avalonian Britain and Sweden, and are distinct from LaurentianL. americanus. AnL. americanusZone cannot be identified in Avalonia or Baltica, and the first appearance datum (FAD) of purported ‘L. americanus’ is not suitable as a standard for the base of the highest Cambrian stage.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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".