Shelf-break glaciation and an extensive ice shelf beyond northwest Greenland at the Last Glacial Maximum
Bibliographic record
Abstract
The analysis of seafloor glacial landforms can provide important constraints on the past behaviour of ice sheets, including their extent at the Last Glacial Maximum and the controls on their subsequent retreat. The continental shelf and slope offshore of northwest Greenland have been sparsely surveyed, however, limiting our understanding of ice sheet extent and dynamics in this sector during the pre-satellite era. Here we use newly acquired high-resolution geophysical data to map and interpret the distribution of glacial landforms across the hitherto unexplored banks of northern Melville Bay and the adjacent slope and deep-sea basin. In contrast to previous conceptual models, our seafloor observations suggest that shelf-break glaciation was attained along the entire northwest Greenland margin at the Last Glacial Maximum, including beyond the shallow banks. The landforms that we map on the continental slope provide strong support for the existence of an ice shelf spanning northern Baffin Bay. Sub-ice shelf keel scours in water depths of down to 1220 m reveal that this ice shelf was at least 1100 m thick at its grounding zone. The orientation of sub-ice shelf landforms suggests that the ice shelf was fed mainly by the supply of ice to northern Baffin Bay from the Lancaster Sound Ice Stream of the Canadian Arctic Archipelago. The Baffin Bay ice shelf buttressed several large ice streams of the Greenland, Innuitian and Laurentide ice sheets at the Last Glacial Maximum, and its break-up may have contributed to instigating the deglacial retreat of these ice streams from the shelf edge. • We use newly acquired bathymetric data to map glacial landforms in Melville Bay. • Northwest Greenland Ice Sheet reached the shelf break at the Last Glacial Maximum. • We present geomorphological evidence for a former ice shelf in northern Baffin Bay.
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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 | 0.000 | 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) | 0.003 | 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 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".