Chapter 37 U–Pb SIMS zircon geochronology of Triassic and Jurassic sandstones on northwestern Axel Heiberg Island, northern Sverdrup Basin, Arctic Canada
Bibliographic record
Abstract
Abstract Detrital U–Pb zircon age data from five stratigraphically controlled Mesozoic sandstones collected from a relatively continuous section in northwestern Axel Heiberg Island are used to evaluate the sediment dispersal patterns and source areas of the northern Sverdrup Basin. Three distinctive provenance types are identified. Early Triassic, Late Triassic and Middle Jurassic samples are dominated by Permo-Triassic zircons and are inferred to be derived from the Taimyr Peninsula/Polar Urals, the New Siberian Islands or some unexposed source submerged beneath the Arctic Ocean. The presence of chrome spinel in these samples suggests a component of mafic–ultramafic material in the source. An Early Jurassic sample is dominated by late Neoproterozoic–early Silurian zircons, which correlate with the Caledonian and Timanian orogens of the Barents Shelf region. A Late Jurassic sample is dominated by Meso-, Palaeoproterozoic and Archaean zircons interpreted to be sourced from the Canada–Greenland shield. Supplementary material: Heavy mineral data (Table S1) and U–Th–Pb ion microprobe analytical data (Table S2) are available at http://www.geolsoc.org.uk/SUP18475 .
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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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 0.001 |
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".