Geochemistry and Geochronology Of REE-Th-U Pegmatites in the Alces Lake Area, Saskatchewan, Canada, with a Focus on Monazite and Zircon
Bibliographic record
Abstract
Abstract This paper presents an original petrochronological study investigating the genesis and time of emplacement of variable grade rare earth element mineralization of two highly mineralized zones (Wilson and Ivan) at the unique rare earth element Alces Lake deposit/prospect (Saskatchewan, Canada). The high-grade mineralized occurrences are hosted in monazites and are associated predominantly with felsic to mafic pegmatites, but also with biotite schists (glimmerites). Various analytical techniques have been utilized in order to characterize monazite and zircon grains, including optical microscopy study, X-ray fluorescence mapping of selected samples, scanning electron microscope, electron microprobe characterization, and laser ablation inductively coupled plasma-mass spectroscopy dating of monazite and zircon grains from two studied zones. The investigated monazite-bearing pegmatitic bodies display peraluminous signatures and are dominated by a quartz + K-feldspar + plagioclase + biotite (±muscovite) + rutile + monazite + zircon assemblage. The pegmatites are strongly enriched (well exceeding 10,000 times chondrites) in light rare earth elements and are depleted in heavy rare earth elements. The monazite forms homogenous to complexly zoned subhedral to fully rounded, corroded crystals variable in size and distribution and characterized by extremely high rare earth element and high Th and U contents. When present, the chemical zoning is characterized as (1) concentric (oscillatory growth zoning) and (2) patchy zoning. U-Pb dating of monazite grains (composite ages) at 1945.7 ± 13 Ma (Wilson Zone) and 1930.1 ± 12.7 Ma (Ivan Zone) and zircon (composite ages) at 1859.2 ± 13.9 Ma (Wilson Zone) and 1888.96 ± 5.8 Ma (Ivan Zone) imply that rare earth element mineralization at Alces Lake is related to high-grade thermotectonic events of the Taltson and Trans-Hudson orogenies, and possibly the Snowbird orogeny. Thus, the mineralized pegmatites at Alces Lake are interpreted to have formed by partial melting, melt (+xenocrystic and/or xenolithic restite) migration, and subsequent assimilation, magma mixing, and fractional crystallization during the thermotectonic events from 1946–1930 Ma to 1890–1860 Ma.
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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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".