Generation of a heavy-mineral glacial indicator dispersal train from a diabase sill, Nipigon region, northwestern Ontario
Bibliographic record
Abstract
The heavy clinopyroxene mineral pigeonite forms a glacial indicator dispersal train originating from diabase intrusions in the Nipigon region of northwestern Ontario. Analysis and interpretation of the pigeonite dispersal pattern adjacent to the up-ice portion of the diabase provides a number of insights into the nature of glacial erosion of bedrock and the generation of heavy-mineral dispersal trains. Bedrock erosion and entrainment rates at the time of pigeonite dispersal train formation were high (314 mm·a1), suggesting that bedrock erosion was rapid yet spatially and temporally restricted. Contrasting erosion rates between the diabase and surrounding greenstone lithologies suggests that modern shield topography is not an assemblage of equilibrium bedforms with respect to the ice sheet. This agrees with hypothesized low total erosion of shield bedrock during the Pleistocene. Pigeonite grain size coarsens over the diabase source, indicating that most of the pigeonite was quarried from outcrops as coarse diabase fragments. Down-ice of the diabase source the mean particle size of pigeonite recovered from till decreases, suggesting most of the pigeonite was liberated from bedrock by the comminution of coarse diabase clasts during glacial transport. While the conclusions drawn from this study may not necessarily apply to all heavy-mineral dispersal trains, the interpretive framework provides a foundation for comparative studies.
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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 | 0.001 |
| Scholarly communication | 0.001 | 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".