Chronology and glass chemistry of tephra and cryptotephra horizons from lake sediments in northern Alaska, USA
Bibliographic record
Abstract
Abstract Holocene tephrostratigraphy in Alaska provides independent chronology and stratigraphic correlation in a region where reworked old (Holocene) organic carbon can significantly distort radiocarbon chronologies. Here, we present new glass chemistry and chronology for Holocene tephras preserved in three Alaskan lakes: one in the eastern interior and two in the southern Brooks Range. Tephra beds in the eastern interior lake-sediment core are correlated with the White River Ash and the Hayes tephra set H (~4200–3700 cal yr BP), and an additional discrete tephra bed is likely from the Aleutian arc/Alaska Peninsula. Cryptotephras (nonvisible tephras) found in the Brooks Range include the informally named “Ruppert tephra” (~2700–2300 cal yr BP) and the Aniakchak caldera-forming event II (CFE II) tephra (~3600 cal yr BP). A third underlying Brooks Range cryptotephra is chemically indistinguishable from the Aniakchak CFE II tephra (4070–3760 cal yr BP) and is likely to be from an earlier eruption of the Aniakchak volcano.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 teacher head, 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".