Geochemical and Nd isotopic evidence for sedimentary-source changes in the Devonian miogeocline of the southern Canadian Cordillera
Bibliographic record
Abstract
Sedimentological evidence indicates that clastic sediments of the Western Canada Sedimentary Basin were derived predominantly from the north and east, an exception being the westerly sourced Sassenach Formation in the Upper Devonian. A comparison of geochemical and Sm-Nd isotopic data of the Sassenach Formation and the underlying Perdrix and Mount Hawk Formations, which have easterly sources, support a change in sedimentary provenance. The Frasnian Perdrix and Mount Hawk Formations have initial ϵ Nd values of −7 to −8.5. This range of values is higher than that of the underlying Precambrian basement and reflects a mixture of older and younger crustal detritus (Late Proterozoic to Devonian) eroded and transported from orogens in the Arctic. The overlying Famennian Sassenach Formation yields lower initial ϵ Nd values that decrease from as high as −8.5 at the base to about −11 near the top. The lower ϵ Nd values of the Sassenach Formation imply that the western crustal source of the Sassenach sediments was, on average, older than the eastern crustal sources of the underlying formations. This older western source appears to be related to uplift and reworking of older miogeosynclinal sediments in the west as a result of compression related to the Antler orogeny.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.015 | 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".