Metamorphosed Proterozoic Zn-Pb-Ag Mineralization in the Foster River Area, Northern Saskatchewan, Canada
Bibliographic record
Abstract
Metamorphosed Zn-Pb occurrences (Fable Lake, George, Sito South, Sito Southwest, Sito West, Sito East, Robyn Lake, and Mackie Lake) with high Zn:Pb ratios occur in the Foster River area, northern Saskatchewan, on the southeast margin of the Paleoproterozoic Wollaston Domain. The Sito East prospect, the largest of these occurrences, contains ~50,000 tonnes of 4.5% Zn, with one drill intercept containing 11 m of 4.2% Zn and 0.6% Pb. Most prospects are hosted in a thin, areally extensive metaquartzite within a thick sequence of metasiltstones and metaquartzites in the middle of the Paleoproterozoic Wollaston Group. Occurrences in metaquartzites and metaarkoses, which locally contain gahnite, spessartine, and/or graphite, are spatially associated with metaexhalites (iron formation and quartz garnetite) and strata-bound metamorphosed hydrothermal alteration zones (nodular sillimanite rock). Post-Archean Australian shale-normalized rare earth element (REE) patterns of all three rock types are characterized by light REE enrichment, positive Ce anomalies, neutral to strongly negative Eu anomalies, and heavy REE depletion, consistent with an environment of deposition distinguished by a high (>30 wt %) continental detrital component and formation from or interaction with low-temperature (≤250C), near-neutral pH and high fO2 fluids. Sulfur isotope compositions of sulfides at Foster River are highly enriched in 34S (δ34S = 26.238.1, n = 20) and resulted from microbial reduction of partially reduced seawater sulfate in a restricted basin. The spatial association of spessartine- and gahnite-bearing lithologies and silicate facies iron formation with Paleoproterozoic base metal sulfides in a psammopelitic host sequence implies similarities between sulfide mineralization in the Foster River area and Broken Hill-type Pb-Zn-Ag deposits. However, the markedly enriched δ34Ssulfide compositions, low Pb/(Pb + Zn) and Ag/(Pb + Zn + Ag) ratios, low Ag contents, and apparent absence of metavolcanic and metavolcaniclastic rocks in the dominantly clastic rock sequence hosting the sulfides in the Foster River area suggest that these occurrences are part of a metamorphosed sedimentary exhalative system with Broken Hill-type affinities, similar to that associated with the formation of the Gamsberg Zn (South Africa), Kanmantoo Group Pb-Zn (South Australia), and Sullivan Pb-Zn (Canada) deposits.
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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 | 0.003 |
| 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) | 0.004 | 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".