A SPURRITE-, MERWINITE- AND SREBRODOLSKITE-BEARING SKARN ASSEMBLAGE, WEST CLEARWATER LAKE IMPACT CRATER, NORTHERN QUEBEC
Bibliographic record
Abstract
The meteorite impact that created the 32-km-wide Late Carboniferous West Clearwater structure, situated about 125 km east of the Hudson Bay arc, northern Quebec, formed a sheet of impact melt now exposed on a central ring of islands. We describe the textures and mineralogy of two xenoliths of partially metamorphosed limestone. These blocks represent recrystallized remnants of a cover of Middle Ordovician limestone, now completely eroded in the area. The fossiliferous dolomite-bearing limestone recrystallized to granoblastic calcite + periclase marble when the blocs landed in the sheet of impact-generated melt. The silica content of the marble led to the formation of a sanidinite-facies assemblage of unusual nesosilicates such as spurrite, merwinite, and monticellite. Aluminian srebrodolskite, Ca 2 (Fe 3+ ,Al) 2 O 5 , is found in material with a composition similar to “Portland cement clinker”. Phase equilibrium and stratigraphic data constrain the minimum peak conditions of metamorphism at T > 815°C, P X (CO 2 ) > 0.1. Retrograde mineral assemblages indicate that X (CO 2 ) dropped to less than 0.1 shortly after the peak of metamorphism. Portlandite and brucite formed during the late hydration of the assemblage upon cooling.
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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) | 0.011 | 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".