A record of the Steptoean Positive Carbon Isotope Excursion (SPICE; Cambrian, Paibian) from the Cow Head Group, western Newfoundland
Bibliographic record
Abstract
Analysis of biostratigraphically dated boulders demonstrates that the Steptoean Positive Carbon Isotope Excursion (SPICE) is recorded in debris flow conglomerates of the Downes Point Member of the Shallow Bay Formation in western Newfoundland. Fifteen boulders composed of bioclastic carbonates were assigned to five faunas based on assemblages of agnostids and trilobites. The Glyptagnostus reticulatus and “ Innitagnostus” inexpectans faunas correlate into strata that record the rising limb of the SPICE in its type area of Nevada and Utah, whereas equivalents of the Acmarhachis kindlei Fauna lie in the interval that records peak δ13C values. The Crepicephalus and Triorygma burkhalteri faunas correlate into pre- and post-SPICE strata, respectively. δ13C values for boulders from the three faunas correlative with the SPICE are significantly higher than “background” levels of the pre- and post-SPICE boulders, but the maximum value in the A. kindlei Fauna (1.5‰) is less than half of the peak values recorded in Nevada and Utah. The values are, however, in line with those reported from the Port au Port Peninsula of Newfoundland, which reach 2.2‰. The differences in magnitude between Newfoundland and Nevada–Utah hint at differences in the expression of the SPICE in different geographic regions of the Laurentian continent that might reflect oceanographic conditions.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".