Lateglacial and Holocene paleoenvironmental changes recorded in lake sediments, Brock Plateau (Melville Hills), Northwest Territories, Canada
Bibliographic record
Abstract
Sediments from South Lake, Brock Plateau (Melville Hills), Northwest Territories, provide one of the longest postglacial records from the mainland western Canadian Arctic, outside of eastern Beringia. Sedimentation commenced at least 13 900 cal. yr BP, and possibly as early as 16 000 cal. yr BP, in response to early deglaciation of the site. Pollen is present throughout the record, with an initial Artemisia-Salix assemblage indicative of very cold conditions, consistent with a locally severe Younger Dryas Stade or simply continued proximity of the Laurentide Ice Sheet margin ( c. 12 700 to 11 500 cal. yr BP). At c. 11 000 cal. yr BP, abiotic proxies signal a transition to warmer conditions, corroborated by a pollen assemblage dominated by Betula and Cyperaceae. Although South Lake was biologically productive during the early Holocene ( c. 11 000 to 7000 cal. yr BP), diatoms and other siliceous organisms are notably absent from the record, suggesting severe silica limitation. Rises in Alnus crispa and Picea mariana pollen at c. 7000 cal. yr BP suggest cooling and/or an increase in effective moisture. Wetter conditions and increased hydrological inputs and silica supply likely led to the establishment of a pioneering diatom community at c. 6500 cal. yr BP. Decreased organic sedimentation after c. 2000 cal. yr BP suggests cooler conditions. Additionally, changing niveo-eolian deposition of sand on lake ice varied with a c. 3000-year periodicity through the entire record. The South Lake multiproxy record supports the hypothesis that the Brock Plateau was one of the earliest deglaciated regions during the late Wisconsinan.
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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 | 0.000 | 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".