Source, timing, frequency and flux of ice‐rafted detritus to the Northeast Atlantic margin, 30–12 ka: testing the Heinrich precursor hypothesis
Bibliographic record
Abstract
Haapaniemi, A.I., Scourse, J.D., Peck, V.L., Kennedy, H., Kennedy, P., Hemming, S.R., Furze, M.F.A., Pieńkowski, A.J., Austin, W.E.N., Walden, J., Wadsworth, E. & Hall, I.R. 2010: Source, timing, frequency and flux of ice‐rafted detritus to the Northeast Atlantic margin, 30–12 ka: testing the Heinrich precursor hypothesis. Boreas , Vol. 39, pp. 576–591. 10.1111/j.1502‐3885.2010.00141.x. ISSN 0300‐9483. Increased fluxes of ice‐rafted detritus (IRD) from European ice sheets have been documented some 1000–1500 years before the arrival of Laurentide Ice Sheet (LIS)‐sourced IRD during Heinrich (H) events. These early fluxes have become known as ‘precursor events’, and it has been suggested that they have mechanistic significance in the propagation of H events. Here we present a re‐analysis of one of the main cores used to generate the precursor concept, OMEX‐2K from the Goban Spur covering the last 30 ka, in order to identify whether the British–Irish Ice Sheet (BIIS) IRD fluxes occur only as precursors before H layers. IRD characterization and planktonic foraminiferal δ 18 O measurements constrained by a new age model have enabled the generation of a continuous record of IRD sources, timing, frequency and flux, and of local contemporary hydrographic conditions. The evidence indicates that BIIS IRD precursors are not uniquely, or mechanistically, linked to H events, but are part of the pervasive millennial‐scale cyclicity. Our results support an LIS source for the IRD comprising H layers, but the ambient glacial sections are dominated by assemblages typical of the Irish Sea Ice Stream. Light isotope excursions associated with H events are interpreted as resulting from the melting of the BIIS, with ice‐sheet destabilization attributed to eustatic jumps generated by LIS discharge during H events. This positive‐feedback mechanism probably caused similar responses in all circum‐Atlantic ice‐sheet margins, and the resulting gross freshwater flux contributed to the perturbation of the Atlantic Meridional Overturning Circulation during H events.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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 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".