Proterozoic and Archean geology of the Nipigon Embayment: implications for emplacement of the Mesoproterozoic Nipigon diabase sills and mafic to ultramafic intrusions
Bibliographic record
Abstract
The Nipigon Embayment is underlain by Archean rocks of the English River, Wabigoon, and Quetico subprovinces, and intruded along the west side by late- to post-tectonic mafic to ultramafic intrusions. The early Mesoproterozoic ultramafic to felsic Badwater intrusion and felsic English Bay Complex are located in the northwest corner of the Nipigon Embayment. Three mafic to ultramafic intrusions, the Disraeli, Seagull, and Hele intrusions, are located south of Lake Nipigon, and the Kitto intrusion is located east of the lake. A number of mafic to ultramafic bodies (Jackfish (Island), Shillabeer, Kama Hill, Nipigon Bay) have only limited outcrops. The gabbroic Nipigon diabase sills intrude all other rocks in the Nipigon Embayment and generally have a consistent mineralogy and geochemistry, except for the Inspiration sill(s) and the McIntyre Sill. Geological and geophysical data suggest emplacement of the ultramafic intrusions by mechanisms similar to those controlling emplacement of the saucer-shaped diabase sills. These mechanisms are partially dependent on a series of pre-existing north-, northwest-, and northeast-trending faults formed prior to Keweenawan magmatism. The presence of sills, rather than dykes, indicates that the Nipigon Embayment was not extensional during the Keweenawan Midcontinent Rift, suggesting that the Nipigon Embayment is not a classic failed arm.
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| 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".