Ice‐Rafted Detritus of the Southeast Grand Banks Slope, Newfoundland, Throughout Heinrich Layers 1 to 5a: 2. Magnetic Properties
Bibliographic record
Abstract
Abstract Ocean‐wide “Heinrich event” layers marked by weakly magnetic dolomitic ice‐rafted detritus (IRD) from the Hudson Bay region are a prominent signature of Laurentide Ice Sheet surges. Contrary to intuition, the Heinrich layers of the Ruddiman Belt IRD exhibit maxima of magnetic susceptibility. Building on IRD petrology and abundance in sediments from the southeast Grand Banks Slope of Newfoundland described in Part I of this study, this Part II presents bulk rock magnetic, major element and grain‐size data as well as rock magnetic analyses of 22 classified IRD lithologies. By stratigraphically, computationally and statistically comparing magnetic with other bulk sediment properties and lithology‐specific IRD counts, we analyze, how the various magnetic IRD species and the glaciomarine background sedimentation generate the observed magnetic susceptibility record. How to infer from microscopically identifiable, but subordinate coarse IRD to the apparently greater impact of the unclassifiable fine IRD fraction is critical for this quest. We show that multi‐domain magnetite, originating from plutonic Canadian Shield rocks, especially muscovite‐biotite granite, dominates and shapes bulk susceptibility records more than all other IRD lithologies. Inverse correlations of Ca/Sr and K/Fe ratios, proxies for dolomitic and granitic IRD, delineate that the magnetic enhancement by the granitic detritus is partly compensated by co‐deposited weakly magnetic dolomitic detritus in the mid‐phase of Heinrich events. Modeling bulk susceptibility from various non‐magnetic records suggests that large parts of fine IRD did not settle directly from melting overpassing icebergs, but seem to have been redistributed and sorted by ocean currents and gravity flows.
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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 | 0.000 | 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 | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 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 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".