Ice‐Rafted Detritus of the Southeast Grand Banks Slope, Newfoundland, Throughout Heinrich Layers 1 to 5a: 1. Petrology and Abundance
Bibliographic record
Abstract
Abstract The Late Pleistocene stratigraphic sequence of Heinrich event layers 1 to 5a shows a high petrological diversity with systematically varying abundances of specific ice‐rafted detritus (IRD) species. Our study core GeoB18530‐1 from the southeastern Grand Banks Slope of Newfoundland resolves these in continuity and considerable detail. Using digital light microscopy and thin section analysis, the compositional mineralogy of coarse‐grained IRD particles was photographically reproduced, petrographically examined, accurately described and named. From 8,243 identified particles, we established a new IRD classification scheme of 22 optically discernible prevalent IRD rock types and rock‐forming minerals. The abundance of each IRD species was counted at 2.3 cm resolution over the lower core section featuring six 30–50 cm thick Heinrich layers and similarly wide interlayers. This high‐resolution time series provides a complex geological record of the Laurentide Ice Sheet calving and episodic collapse during MIS 3 and MIS 2. The count statistics allow IRD species to be divided into three separate groups based on their equal, over‐, or under‐representation in Heinrich layers relative to their interlayers. Heinrich layers 1, 2, 4, and 5 were found to be petrologically similar, while Heinrich layers 3 and 5a have some deviating IRD constituents, conforming to previous findings. Ooid‐bearing dolomite IRD dominates the mid‐section of all Heinrich layers, whereas muscovite‐biotite granite IRD is enhanced at their tops and bottoms. The characteristic IRD lithology of the interlayers changes gradually over the investigated Late Wisconsinan Stage (60–15 ka).
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".