Post-LGM sedimentation history and deglaciation processes in the southern Gulf of St. Lawrence, Canada
Bibliographic record
Abstract
During the last glacial period, continents and surrounding shelves in high latitude regions of the Northern Hemisphere were covered by ice sheets. Their retreat after the Last Glacial Maximum resulted in isostatic adjustments of the previously glaciated landmass and post-glacial changes in relative sea level during the late Pleistocene and Holocene. Many questions, however, remain about the timing and impact of the ice retreat and of short-lived climatic events on continental shelf environments. This study aims to reconstruct the sedimentation and deglaciation processes on the continental shelf of the southern Gulf of St. Lawrence (Canada) over the past 14 ka by investigating changes in the sedimentation patterns and paleo-environments. Using information from sub-bottom profiles, sediment cores, and multibeam bathymetry, this study finds that most of the continental shelf was flooded 13.6 ka ago, as evidenced by the presence of Bølling-Allerød marine sediments at a water depth of ∼50 m and ∼15 km off the modern coastline, which also suggests an earlier retreat of the Laurentide Ice Sheet than suggested by previous studies. We estimate sedimentation rates for the Bølling-Allerød of ∼0.4 cm a −1 , which increased up to 1 cm a −1 during the Younger Dryas cooling event, likely associated with increased storm-wave activity and sea ice development caused by deteriorating climatic conditions. The presence of an erosional truncation atop Younger Dryas sediments indicates a late Pleistocene-early Holocene relative sea level fall and associated lowstand. Based on our new data, we established a geological model that highlights sedimentation processes since the Last Glacial Maximum and demonstrate the potential impact of short-lived climatic events on the former ice margin during deglaciation. • Significant influence of the Bølling-Allerød and Younger Dryas on sedimentation. • Buried sediment basins and channels filled by late Pleistocene sediments. • Sedimentation rates >0.4 cm a −1 during deglaciation. • Erosional truncation possibly related to the Holocene RSL lowstand. • Marine sedimentation close to the coast of PEI as early as ∼13.6 ka BP.
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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 | 0.002 | 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 | 0.001 |
| 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".