Dawson tephra: a prominent stratigraphic marker of Late Wisconsinan age in west-central Yukon, Canada
Bibliographic record
Abstract
Dawson tephra is the most prominent tephra bed in the Quaternary deposits of the Klondike and Sixtymile areas of the Yukon. It occurs in organic-rich, reworked, Late Wisconsinan loess deposits that occupy valley-bottom sites and has a maximum thickness of 30 cm, although most values are in the range of 1530 cm. The tephra consists of thin, bubble-wall shards that have a distinctive, rhyolitic composition. Orthopyroxene, plagioclase, magnetite, and ilmenite are relatively abundant in the small crystal component, which also contains minor amounts of clinopyroxene, apatite, and zircon. Overall, the composition of Dawson tephra bears a close resemblance to that of the well-known Old Crow tephra, and, like that tephra, demonstrates a source in the Aleutian Alaska Peninsula region. Given that the nearest vent in the Alaska Peninsula is 700 km distant from the Klondike, it follows that this explosive eruption must have been of great magnitude, distributing tephra over southern and central Alaska and the Yukon. The age of this eruption is not precisely known, but it did occur during the interval 2212 ka.
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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 | 0.002 |
| 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".