Till provenance across the terminus of the Dubawnt Lake ice stream, central Nunavut
Bibliographic record
Abstract
The composition of glacial sediments across the Dubawnt Lake ice stream in central mainland Nunavut was examined to assess the potential influence of fast ice flow on sediment transport. Major changes in clast content, texture, and geochemical composition are observed in till collected over and beyond the ice-stream footprint. These changes coincide with an ice-front position at the southern segment of the MacAlpine moraine system. The till composition over the ice stream reflects a distal provenance, rich in undeformed Dubawnt Supergroup sandstone debris from the Thelon basin, relatively clay-rich, SiO2-rich, and depleted in most trace and major elements (except SiO2). Although giving an indication of the long glacial transport distance of exotic quartz sandstone from the Thelon Basin (~80 km), the SiO2 content in the matrix (<0.063 mm) is not entirely appropriate to reflect the Thelon Basin component in the till because of the abundance of quartz-rich rocks in the local crystalline basement. The ratio of total versus partial concentrations of Sr in till is a better suited proxy in the Thelon tectonic zone region; Sr ratios below ~10 characterize till composition within the Dubawnt Lake ice stream. Beyond the ice stream, till composition reflects a more local provenance, derived from the underlying Thelon tectonic zone rocks, and Sr ratios increase up to ~24. Furthermore, atypical clay contents in till, related to changes in till facies or stratigraphy rather than a change in provenance, can have a significant influence on till composition and may complicate the interpretation of till geochemistry. The work has implications for mineral exploration in the Rae geological province of the Canadian Shield.
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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 | 0.001 | 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) | 0.001 | 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".