Geology of Paleozoic Platform-edge Units in the West Newfoundland Appalachians
Bibliographic record
Abstract
The Appalachian mountains in western Newfoundland preserve the early Paleozoic passive continental margin of the continent Laurentia. Shallow- and deep-water carbonate units on the margin are subdivided into established stratigraphic groups, but platform-edge units are poorly understood. Three major orogenic episodes are recognized in the area. The Ordovician Taconian event is interpreted as the result of arc–continent collision that emplaced the Bay of Islands Ophiolite. Subsequent Salinian and Acadian events record accretion at the active Laurentian margin following subduction polarity reversal. Fieldwork was conducted to resolve unclear associations between the platform-edge units and resolve mapping discrepancies that affect their distribution. A revised “Pinchgut Lake Group” is proposed to include the Reluctant Head Formation and overlying Weasel Formation. The base of the Weasel Formation is placed below the lowermost conglomerate greater than 4 m thick. The Reluctant Head Formation comprises thinly bedded limestone and ribbon limestone. Facies within the Weasel Formation include limestone conglomerate, undisrupted ribbon limestone, and disrupted ribbon limestone. Limestone conglomerate facies vary subtly, but quartz sand in grainstone matrix occurs in discrete intervals that aid in correlation between distant exposures of the Pinchgut Lake Group. Features within the disrupted ribbon limestone are suspected to be products of synsedimentary deformation. The style of margin represented by the Pinchgut Lake Group differs from that of the Cow Head Group, likely as a consequence of a margin morphology inherited from rifting. Samples from the Weasel Formation were prepared for carbon and oxygen stable isotope analysis. Significant diagenesis did not occur and samples retain near-primary values. Comparisons to other compiled sections from western Newfoundland enables time-correlation of the Pinchgut Lake Group and the identification of several excursions within the unit. The lowest correlatable quartz sand interval is associated with a major carbon isotope excursion event, the Steptoean Positive Isotope Carbon Excursion (SPICE). The upper quartz interval preserved within the Pinchgut Lake Group occurs near the Cambrian – Ordovician boundary and negative Hellnmaria–Red Tops Boundary (HERB) excursion.
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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 | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 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".