The Southern Breccia Metasomatic Uranium System of the Great Bear Magmatic Zone, Canada
Bibliographic record
Abstract
The Southern Breccia metasomatic uranium (U) showings are located 1 km south of the NICO deposit, an iron oxide-copper-gold (IOCG) deposit, in the Great Bear magmatic zone of Canada. The timing of both occurrences is tightly constrained to 1873–1868 Ma, linking formation of the albitite-hosted U to development of IOCG mineralization. During this period, regional iron oxide and alkali-calcic metasomatism formed: Na (albite), high-temperature Ca-Fe (amphibole + magnetite), high-temperature Ca-K-Fe (amphibole + magnetite + biotite ± K-feldspar), high-temperature K-Fe (K-feldspar/biotite + magnetite), K (K-feldspar ± biotite), and low-temperature K-Fe-Mg (K-feldspar + hematite + chlorite) assemblages. Primary uraninite and brannerite occur within high-temperature K-Fe alteration composed of magnetite + K-feldspar ± biotite-cemented breccias developed in earlier albitite. The chemistry of primary uraninite supports precipitation from high-temperature, magmatic-derived fluids, as previously proposed for the NICO deposit. Field relationships, petrography, whole-rock geochemistry, and geochronology indicate that alteration of the Southern Breccia corridor host rocks was coeval with early alteration at NICO, whereas U mineralization postdated Au-Co-Bi at NICO. The linkage of the Southern Breccia to the regional iron-oxide and alkali-calcic alteration system that generated the NICO deposit presents a new driver for formation of albitite-hosted U deposits and highlights an exploration target in IOCG districts globally.
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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 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".