Age and significance of the Fire Bay assemblage: an Ordovician arc fragment within the Clements Markham belt, northwestern Ellesmere Island, Canada
Bibliographic record
Abstract
The Fire Bay Formation of Trettin (1998), Clements Markham belt, Ellesmere Island, Canada, includes volcanic rocks described as Silurian in age based on Llandovery graptolites in adjacent clastic rocks. New field observations suggest the Llandovery fossils are from packages of the Silurian Danish River and/or Lands Lokk formations that are fault-bounded rather than stratigraphically tied to Ordovician sections that contain a 470.0 ± 0.2 Ma lithic tuff, volcaniclastic units with maximum depositional ages (MDAs) of 466 ± 2 and 462 ± 2 Ma based on detrital zircon, volcanic clasts with ages of 498 ± 6, 478 ± 4, and 477 ± 8 Ma, and Ordovician conodonts and graptolites of Darriwilian and Sandbian age, respectively. Since the Fire Bay Formation of Trettin (1998) lacks a type section and is fault-bounded with ambiguous age relationships, Ordovician volcanic units and fault-bounded clastic rocks correlated with the Hazen Formation are both included in the Fire Bay assemblage following the original interpretations of Trettin and Nowlan (1990). The Fire Bay assemblage records juvenile Ordovician arc magmatism proximal to the Pearya terrane. The adjacent Lands Lokk Formation yields bimodal age peaks at 440–430 and 465 Ma, MDA of 424 ± 3 Ma, and εHf(t) values of −5 to +10. The signature matches Ordovician Pearya units and Silurian circum-Arctic arc sources but there is no evidence for Silurian arc magmatism between the Pearya terrane and Laurentian margin, compatible with Pearya accretion during oblique Ordovician arc collision and Silurian sinistral translation along the northern Laurentian margin.
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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 | 0.003 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.001 | 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".