ISOTOPE GEOCHEMISTRY OF SCABLAND FLOOD DEPOSITS
Bibliographic record
Abstract
Argon and neodymium isotope geochemistry provide a means of tracking Scabland Flood sediment from source to sink. Analysis of sediment from locations along the flood path and from two marine sediment accumulation sites elucidate patterns of sediment mixing on land, subsequent unmixing at sea, and marine sediment transport pathways. Slackwater deposits in the Tucannon and Willamette valleys are characterized by old K/Ar ages of fine-grained sediment (240 to 360 Ma), younger 40Ar/39Ar ages of individual micas (mean ages from 70 to 150 Ma), and moderately negative εNd values (-8.5 to -10.5). Similarly old K/Ar ages (210 to 390 Ma) and negative εNd values (-8.5) link glacial outburst flood layers from sediment core MD02-2496 offshore Vancouver Island to the Scabland Floods. This isotopic link shows that Scabland Floods sent plumes of fine-grained sediment >400 km to the north in the Pacific Ocean. A high-resolution geochemical record from MD02-2496 identifies 44 Scabland Flood layers in the core. Sixteen radiocarbon dates spanning the glacial flood interval provide an absolute chronology, showing cyclical deposition with ~50- to 80-year periodicity between ~19.3 and ~14.9 ka. Additionally, 40Ar/39Ar age spectra of individual mica grains from a late Pleistocene Astoria Fan turbidite bed are similar to age spectra from Scabland Flood slackwater deposits, reinforcing the connection between this turbidite sequence and glacial outburst floods.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".