Multi-proxy reconstruction of climate changes in the Lower St. Lawrence Estuary, Canada, during the Middle and Late-Holocene
Bibliographic record
Abstract
The micropaleontological and palynological content, and geochemical and isotopic composition of a marine sediment core collected off Pointe-des-Monts in eastern Québec, Canada, reveal regional palaeoclimatic and paleoceanographic conditions in the Lower St. Lawrence Estuary over the last ~8200 years. The pollen and spore content allows comparison with the terrestrial palynostratigraphy, whereas dinoflagellate cysts and benthic foraminifera are used to reconstruct sea-surface conditions and bottom water properties, respectively. The dinocyst-based reconstructions indicate shifts between estuarine and oceanic conditions with important changes in sea-surface temperature, salinity, and primary productivity. Both the dinocyst assemblages and the quantitative sea-surface estimates highlight a distinct transition at ca. 4200 cal years BP. It is notably marked by a change towards higher salinity, which suggests reduced freshwater discharge, hence lower precipitation in the watershed, during the Late-Holocene. The isotopic composition (δ 18 O and δ 13 C) and assemblages of the benthic foraminifera indicate centennial to millennial frequency variability of bottom water properties, over a general trend towards decreasing temperatures and increasing ventilation from the beginning of the Middle Holocene until the last century. Since then, reverse trends with abrupt warming and decreasing dissolved oxygen content in bottom water have been observed.
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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 | 0.001 | 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) | 0.001 | 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 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".