Variation in plagioclase clouding intensity in Matachewan dykes: evidence for the exhumation history of the northern margin of the Sudbury Igneous Complex
Bibliographic record
Abstract
Early Proterozoic Matachewan mafic dykes that cut the Archean Cartier granite Levack Gneiss Complex north of the Sudbury Igneous Complex (SIC), Canada, are generally metamorphosed to lower amphibolite facies but exhibit locally unaltered plagioclase. These plagioclase feldspars display a clouding similar to that found in the same swarm in the vicinity of the Kapuskasing uplift, about 200 km to the northwest, where the clouding intensity is due to magnetite exsolution and displays a positive correlation with the depth of dyke emplacement. In the Sudbury area, the clouding intensity, obtained by image analysis of thin sections, increases away from the SIC, opposite to the direction of increasing regional metamorphism in the Archean basement. This suggests that the Levack Gneiss Complex north of the SIC was exhumed prior to the intrusion of 2.47 Ga Matachewan dykes and therefore predates the formation of the SIC and associated impact event. The southward tilting of the crust inferred from the plagioclase-clouding data appears to have involved uplift along the Benny Deformation Zone, but the exact age of this deformation is unknown. It may be associated with the 1.81.9 Penokean Orogen, 1.85 Ga Sudbury impact crater, or 2.22.4 Ga Blezardian Orogen.
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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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".