Radiogenic isotope geochemistry applied to the characterization of the provenance of sediments transported by icebergs during the last glacial period: A study in the Galicia Interior Basin
Bibliographic record
Abstract
In the scope of a collaboration with the University of Vigo, the Geobiotec research unit has contributed with studies on the Sr and Nd isotopic fingerprints of the sediments deposited in the Galicia Interior Basin in the last six Heinrich Stadials (HS; climatic oscillations that culminated by massive discharge of icebergs to the North Atlantic during the last glacial period). Strongly negative ƐNd values during HS1 (~15-16 ka), HS2 (~23.5-25 ka), HS4 (~37.5-40 ka) and HS5(~43.8-45.5 ka) are consistent with a Canadian source for the sediments dropped by icebergs. In contrast, higher ƐNd and relatively low 87Sr/86Sr values were recorded during HS3, HS5a, HS6, but also in the initial stages of HS1 (~16-17.5 ka), HS2 (~25-26.3 ka) and HS4 (~40-42 ka), pointing to an European provenance of those sediments. The whole set of data suggests that large European meltwater discharges in the beginning of HS1, HS2 and HS4 could have contributed to the weakening of the Atlantic Meridional Overturning Circulation and, consequently, to the collapse of the ice sheets covering NW Europe and NE America.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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 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".