Crustal recycling during subduction at the Eocene Cordilleran margin of North America: a petrogenetic study from the southwestern Yukon
Bibliographic record
Abstract
The early Eocene (57.355.4 Ma) Bennett Lake and Mount Skukum Volcanic Complexes lie on the Coast Plutonic Complex and Intermontane Belt boundary of the Canadian Cordillera at the British Columbia Yukon border, some 200 km east of the current and Eocene continental margin. Both complexes contain rock types from basaltic andesite to rhyolite in a series of lava and pyroclastic flows. The location relative to the continental margin, the rock types, and the presence of an enhanced LILE/HFSE (large-ion lithophile / high field strength element) signatures in all samples imply that contemporaneous subduction was the controlling factor in the formation of these complexes. The majority of samples, however, return unusually low compatible element concentrations for given rock types. We interpret this data to show that partial melting of the crust was the major source of erupted magmas. One formation of andesites at Mount Skukum and one late dyke at Bennett Lake do show higher concentrations of compatible trace elements, suggesting the presence of primitive magmas in the crust at the time of eruption, which contaminated and were erupted with the crustal melts. SrNd isotopic data at both complexes are consistently primitive regardless of rock type and compatible element content, requiring a primitive crustal source for these magmas. We propose that the complexes were formed as a result of early Eocene subduction of the Kula Plate beneath the Canadian Cordillera. Intrusion of hot primitive melts caused partial melting of young crust to produce the majority of lavas observed. Contamination of these melts by primitive magmas is observed at both Mount Skukum and Bennett Lake.
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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 | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| 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".