Relative importance of hydrological and climatic controls on Holocene paleoenvironments inferred using diatom and pollen records from a lake in the central Hudson Bay Lowlands, Canada
Bibliographic record
Abstract
Postglacial paleoenvironmental changes and landscape development in the Hudson Bay Lowlands in subarctic Canada were inferred using sediment properties and diatom and pollen assemblages in the sediments of a lake raised above the surrounding peatlands in an ice-marginal landform. Coarse-grained, inorganic sediments at the base of the Lake AT01 core suggest a high-energy periglacial environment, following isostatic emergence from Hudson Bay around 6840 cal. BP. Initial diatom assemblages dominated by Fragilaria spp., and pollen of Shepherdia canadensis, indicate early successional conditions in a recently deglaciated environment. Around 6200 cal. BP, tychoplanktonic Fragilarioid diatoms are replaced by large benthics. Coincident increases in Equisetum spores, Cyperaceae pollen and sediment organic matter suggest the establishment of a more productive macrophyte-rich shallow lake. While the Holocene Thermal Maximum and subsequent Neoglacial may have contributed to these shifts, pollen and diatom records suggest only subtle responses to Holocene climatic changes. A core chronology inferred from radioisotopes suggests a hiatus in sediment accumulation between 3650 and 200 cal. BP. Peaks in carbonate inferred from loss-on-ignition and increases in bulk density in that section of the core suggest some effect of erosional or thermokarst processes, or the breaching of a sandbar, now a remnant island in the lake, in the drainage of the lake and ensuing hiatus. Sediment accumulation resumed within the past two centuries; diatom assemblages in the uppermost section are characterized initially by benthic diatoms of smaller valve size compared with the pre-hiatus assemblages. More recently, increases in the planktonic diatom Cyclotella stelligera are recorded, signaling significant environmental changes.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".