Geomorphological analysis of grounding-zone wedges reveals glacial retreat processes on the Labrador Shelf
Bibliographic record
Abstract
Newly acquired high-resolution geophysical data from four glacial cross-shelf troughs of the Labrador Shelf, namely the Okak, Hopedale, Makkovik and Cartwright troughs, are presented in this study. These cross-shelf troughs were repeatedly excavated by the former Laurentide Ice Sheet (LIS) during past glaciations. We map and describe three previously unknown grounding-zone wedges (GZWs) from an area where only sparse information about the retreat of the LIS is available. Based on our geomorphological analysis, we derive the dynamics and the direction of the ice retreat. For the Okak, Makkovik, and Cartwright troughs, the newly identified GZWs indicate fast-flowing ice streams with a high sediment load. We propose that a stable ice grounding-zone paralleled the present-day coastline in the Okak and Makkovik troughs, while in the Cartwright Trough, an ice-margin retreat towards the outlet of Lake Melville is more likely. We date available sediment samples of the deposits that onlap one of the GZWs to 14.5 ka cal BP and can show that the discovered GZWs must be older. This new information updates our understanding of the dynamics of the LIS, particularly at its eastern boundary, the Labrador Shelf and Sea, which is important to better reconstruct the effects of the LIS dynamics on global ocean currents and climate. • Discovery of three grounding-zone wedges on the Labrador Shelf. • Indications for fast-flowing ice streams with high sediment load during deglaciation. • Update of the ice-margin chronology based on the glacial retreat processes.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.002 |
| 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) | 0.029 | 0.001 |
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".