Paleoclimate archive potential of the possibly former sub-glacial Lake Manicouagan (Canada)
Bibliographic record
Abstract
Lakes in formerly glaciated areas are prone to provide valuable paleoclimate archives, which contain information about the glacial processes influencing the region in which the lakes formed. The eastern Canadian provinces Québec, Newfoundland and Labrador are key areas to understand climate changes since the Cenozoic. Lake Manicouagan is a 214 Myr old impact crater lake located in the province of Québec, 220 km north of the Saint Lawrence River. This area was directly affected by the waxing and waning of the Laurentide Ice Sheet at least during the last glaciation. Here, we present high-resolution seismic data imaging the glacially excavated thalweg of Lake Manicouagan and a sedimentary sequence filling it. On that basis, we assess the potential of this sedimentary sequence as a paleoclimate archive. Our high-resolution seismic data reveal a varying shape of the valley throughout the lake. A U-shape of the valley suggests that grounded glacial erosion excavated the thalweg, whereas a narrow V-shape in some areas is indicative of pressurized subglacial meltwater erosion. We discuss three different scenarios regarding the deposition of sediment and the evolution of Lake Manicouagan during the Upper Pleistocene and Holocene: (1) the entire sedimentary sequence was deposited during and after the final retreat of the Laurentide Ice Sheet or (2) the deposits are the result of multiple glacial-interglacial cycles or (3) Lake Manicouagan was a subglacial lake during the last glaciation. We favor the third scenario because it explains missing interglacial units and erosional ice contact surfaces in the sedimentary sequence. Lake Manicouagan holds a valuable paleoclimate archive regardless of the scenario. Either the lake is a high-resolution paleoclimate record of the last 7.5 kyr, or the lake sediments contain pre-deglacial information, located in an area which was directly affected by advance and retreat of the Laurentide Ice Sheet during the Wisconsin glaciation.
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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 | 0.004 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".