Greenlandic debris in Iceland likely tied to Bond event 1 ice rafting in the Dark Ages
Bibliographic record
Abstract
Abstract We report the discovery of exotic igneous, metamorphic, and sedimentary cobbles in raised beach deposits near Breiðavík, northern Iceland. These deposits consist of alternating cobble-, sand-, and silt-dominated facies. A nearby package of sands and silts, dated to the Late Antique Little Ice Age (LALIA; ca. 536–660 CE), provides age constraints for the raised terraces. While the upper terraces are composed exclusively of local basaltic material, the lowermost terraces (~2 m above high tide) contain a mix of basaltic and nonbasaltic cobbles, including quartzofeldspathic gneiss, granitoid, rhyolite, sandstone, and serpentinite. U-Pb geochronologic analysis of zircon revealed dominant age modes of ca. 2800, 1150, 500, and 240 Ma with Lu-Hf isotopic compositions suggesting derivation from Greenland’s North Atlantic craton and Caledonian fold belt. The colder conditions of the LALIA, coupled with increased iceberg calving from the Greenland ice sheet, would have led to enhanced ice-rafted debris (IRD) transport to disparate areas south and east of Greenland. The East Greenland and East Iceland currents transported this IRD from Greenland, with deposition occurring along the Icelandic coast as the icebergs melted. This IRD was likely transported across the North Atlantic during Bond event 1. This process, along with those during other transient cooling events, may explain the age discrepancies between local bedrock and detrital zircons in the Arctic.
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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 | 0.001 | 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 | 0.000 | 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".