Late glacial retreat of the Lancaster Sound Ice Stream and early Holocene onset of Arctic/Atlantic throughflow in the Arctic Island channels
Bibliographic record
Abstract
Multiple proxies in three sediment cores from Northwestern Baffin Bay document the timing of Lancaster Sound Ice Stream (LSIS) retreat that led to Arctic–Atlantic throughflow in Parry Channel, an important source of freshwater that can impact the Atlantic Meridional Overturning Circulation. The Late Glacial to Holocene timing of ice retreat and channel opening and the responses of the regional ocean environment to these events are presented. We use quantitative mineral composition, foraminiferal assemblages, biogenic silica, ice-rafted debris (IRD), and 14C-based age models to document and date the events and environmental changes occurring during deglaciation of this major marine channel. Findings show that retreat of the LSIS into Lancaster Sound occurred before ~15.3 cal ka BP, about 800 years before the onset of major iceberg calving events from the LSIS, named the Baffin Bay Detrital Carbonate events (BBDC 1 and BBDC 0). The end of BBDC 0 occurred at ~10.6 cal ka BP, which coincides with the opening of Parry Channel. A marine environment productive of calcareous benthic and planktic foraminifera, with diminished meltwater, seasonal sea ice, warmer summer temperatures, and inflowing, nutrient-rich Arctic surface water characterizes the interval between the opening of Parry Channel and the opening of Nares Strait. Paired planktic and benthic 14C ages over this 2,200-year interval show diminishing age offsets suggesting progressive mixing of the upper ~850–900 m of the water column. The opening of Nares Strait by ~8.2 cal ka BP coincides with increased biogenic silica in the form of abundant, large centric diatoms and dissolution of CaCO3. The paucity of calcareous organisms after 8.2 cal ka BP resulted in poor chronological control in the cores to interpret changing environments after 8.2 cal 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 | 0.003 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 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".