Could the calcium conundrum in Skytrain shed light on West Antarctic Ice Sheet dynamics? 
Bibliographic record
Abstract
Recent work demonstrates that the Skytrain ice core, retrieved from the Weddell Sea Embayment in West Antarctica, can inform us about the (in-)stability of the Ronne-Filcher Ice Shelf and the West Antarctic Ice Sheet in past warm periods. Here we switch our focus to the Last Glacial period at Skytrain and describe our “Calcium Conundrum”, which may be linked to ice sheet dynamics. The Skytrain calcium record diverges from those of other Antarctic ice cores across several distinct time intervals. The increased Ca at Skytrain is not accompanied by a corresponding increase in other terrigenous elements such as Al. We hypothesize that the elevated Ca intervals result from additional input of relatively local dust, unique to Skytrain. To test this, we present new geochemical measurements on the soluble phase and fully digested dust particles from a ‘regular Ca’ interval (20–31 ka) and an ‘excess Ca’ interval (42–49 ka). Trace element data confirm elevated Ca levels during the excess Ca interval, associated also with a significant Ba increase relative to Al. However, terrigenous elements associated with silicate minerals exhibit no significant difference between the two intervals when normalised to Al. Radiogenic Sr and Nd isotopes of the regular Ca interval fall within range of South American source areas, typical for Antarctica during the Last Glacial Period. In contrast, 87Sr/86Sr and eNd values for the excess Ca interval are significantly different from those of the regular Ca interval. Using a collation of Sr and Nd isotope data of potential source regions, complemented by new measurements on rocks from the nearby Ellsworth Mountains, we assess the possibility that the recurring excess Ca signal during the Last Glacial fingerprints a dynamic ice sheet in the Weddell Sea Embayment that intermittently exposed nearby nunataks to physical erosion and dust transport. Additionally, we report the first (to our knowledge) Ca isotope measurements on ice cores in an effort to further fingerprint the source of the excess Ca.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".