RADIOACTIVE ABYSSAL GRANITIC PEGMATITES AND LEUCOGRANITES IN THE WOLLASTON DOMAIN, NORTHERN SASKATCHEWAN, CANADA: MINERAL COMPOSITIONS AND CONDITIONS OF EMPLACEMENT IN THE FRASER LAKES AREA
Bibliographic record
Abstract
The Fraser Lakes area in the Wollaston Domain, in northern Saskatchewan, Canada, is located 25 km from the southeastern edge of the uranium-rich Athabasca Basin; it hosts a number of U- and Th–REE-bearing granitic pegmatites and leucogranites. At Fraser Lakes Zone B, the pegmatites and leucogranites intrude the deformed contact between Paleoproterozoic metasedimentary gneisses of the Wollaston Group and Archean orthogneisses, and have characteristics typical of the Abyssal pegmatite subclass. For two examples of Group-A U- and Th-enriched pegmatite and leucogranite, and two examples of Group-B Th- and LREE-enriched pegmatite and leucogranite samples that have minimal petrographic evidence of later alteration, we analyzed selected minerals by electron microprobe to provide constraints on the age and temperature of intrusion. The Group-A pegmatites contain uraninite with variable CaO and SiO 2 , indicative of later recrystallization, uranoan thorite spatially associated with complexly zoned zircon (with some intermediate solid-solution between the two minerals), rare coffinite, and titaniferous magnetite and ilmenite where they intrude the Archean orthogneisses. CHIME dating of the most pristine uraninite yielded ages between 1.85 and 1.80 Ga, consistent with crystallization from the pegmatite-forming melt. The Group-B pegmatites contain monazite-(Ce) with significant Th substitution, uranoan thorite, zircon (also showing extensive solid-solution toward thorite), and rare xenotime and pyrochlore. CHIME dating of monazite from the Group-B pegmatites gave older ages of ca. 2.1 to 2.2 Ga, suggesting that they are xenocrysts from the source region of the melt. Biotite dehydration reactions have led to significant development of leucosome in the host pelitic gneisses, and likely resulted in the formation of granitic melt at depth.
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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 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| 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".