Upper Cretaceous diatom biostratigraphy of the Arctic archipelago and northern continental margin, Canada
Bibliographic record
Abstract
Strata in the Canadian Arctic contain diverse and moderately well-preserved Late Cretaceous siliceous microfossil assemblages. One-hundred-twelve samples were analyzed from a composite stratigraphic section (1094m-thick) of the Smoking Hills, Mason River and Kanguk formations. Four sections were examined: (1) Slidre Fjord on Ellesmere Island; (2) Hoodoo Dome on Ellef Ringnes Island; (3) Cape Nares on Eglinton Island; and (4) Horton River on the Anderson Plains, Northwest Territories. Two hundred-three diatom taxa were identified in forty-nine productive samples. Four Upper Cretaceous diatom zones are proposed for the Canadian Arctic based on the biostratigraphic distribution of diatoms: (i) the Upper Cenomanian to Upper Santonian(?) Gladius antiquus Concurrent Range Zone, (ii) the Lower Campanian Costopyxis antiqua Partial Range Zone, (iii) the lower Upper Campanian Trinacria indefinita Interval Zone, and (iv) the upper Upper Campanian Stephanopyxis simonseni Partial Range Zone.The diatom assemblages are similar to those of Alpha Ridge (Arctic Ocean), Ural Mountains (Russia), and Campbell Plateau (SW Pacific Ocean), enabling diatom-based biostratigraphical correlations within the northern high-latitudes and to the southern high-latitudes. A fifth biostratigraphic zone, Azpeitiopsis morenoensis Concurrent Range Zone, is also proposed, based on common and widespread distribution of the nominative taxon in lower to upper Maastrichtian sediments. Sufficient data is now available to establish the construction of a diatom-based standard zonal framework for the Upper Cretaceous.Two new combinations, Trochosira denticulatum (Strelnikova) Tapia and Trochosiropsis polychaeta (Strelnikova) Tapia are here proposed.
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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 | 0.003 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 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".