Extending the western Hudson Bay Lowland Quaternary stratigraphy, in Manitoba Canada, to at least Marine Isotope Stage 10
Bibliographic record
Abstract
Quaternary stratigraphy can improve our understanding of glacial dynamics prior to the Last Glacial Maximum. This study uses a hybrid lithostratigraphy–allostratigraphy approach to decipher the stratigraphic record in the Gillam area of the western Hudson Bay Lowland, Manitoba, Canada. The region experienced multiple glaciations, and previous studies were limited to correlating nonglacial “marker beds” amongst numerous till–till contacts. New study of the tills has led to identification of nine glacial (till) units, one pre-Holocene nonglacial (sorted sediment) unit and a paleosol; constrained by radiocarbon and optical age datasets. The composition of most tills in the Gillam area is calcareous-rich and non-distinctive. Nonetheless, our new ice-flow history shows repeated patterns during at least four glacial–interglacial cycles; dominated by ice flowing from the Quebec–Labrador sector of the Laurentide Ice Sheet. The stratigraphic framework, and a quartz optical age estimate, suggest the intertill organic-rich sorted sediments (“Nelson River Sediments”) were deposited during Marine Isotope Stage (MIS) 7 (∼183 ± 21 ka (1σ MAM, sample HBL22-2)). Quantitative analysis of interglacial pollen from the same interval suggests increased annual precipitation (679.3 ± 201.7 mm) and slightly warmer-than-present summer temperatures (14.5 ± 1.6 °C), within a boreal forested environment ( Picea-dominated) with sufficient moisture and nutrients to allow for fen expansion ( Larix and Cyperaceae). This new interpretation pushes the underlying interglacial “Sundance paleosol” to MIS 9 and the tills below to MIS 10 or older. The regional timing and ice-flow history allow for constraints long into the Pleistocene, providing a rare dataset to constrain future modeling efforts.
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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 | 0.002 | 0.003 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".