The Presence of Carbonic-Dominant Volatiles during the Crystallization of Sulfide-Bearing Mafic Pegmatites in the North Roby Zone, Lac des Iles Complex, Ontario
Bibliographic record
Abstract
Mafic pegmatites in the platinum-group element (PGE)-mineralized Roby zone, Lac des Iles Complex, northwest Ontario, Canada, comprise dikes, veins, and irregular pods of coarse-grained magnesiohornblende, pyroxene, and labradorite-andesine with minor biotite, apatite, Fe-Ti oxides and intercumulus quartz that grades into massive quartz or graphic quartz-base metal sulfide-vysotskite [Pd, Ni(S)] intergrowth at their cores. Quartz, apatite, and magnesiohornblende host primary and secondary assemblages of one- or two-phase carbonic fluid (CO 2 ± up to ~10% CH 4 ± minor H 2 O, N 2 ) inclusions that contain ore metals (Ni, Cu, Pd, Bi, Te, Fe). Rare trails of late-stage, high-salinity, aqueous fluid inclusions are secondary in origin and, therefore, unrelated to the crystallization of the pegmatites. Assemblages of primary carbonic fluid inclusions show considerable variation in mode and temperature of homogenization, reflecting large fluctuations in confining pressure at the time of quartz crystallization of as much as ~1 kbar (in single quartz crystals) and ~2.8 kbars (all data). Independent thermobarometric methods constrain conditions for the following two stages of pegmatite formation (and carbonic fluid entrapment): (1) the crystallization of magnesiohornblende-plagioclase intergrowth at T ~650° to 850°C, and P ~1 to 3 kbars; and (2) the crystallization of quartz at T ~535° to 650°C, and P ~0.4 to 3.2 kbars, setting the maximum depth of emplacement of the Lac des Iles Complex North Roby zone magma at 10 to 12 km. The results indicate that aqueous-dominant volatile phases were absent during the crystallization of pegmatitic gabbroic rocks at the Lac des Iles Complex and that water-poor, carbonic fluid entrapment persisted to well below solidus conditions. A role played by carbonic fluid as a potential transport medium for ligands involved in the precipitation and remobilization of the PGE and base metals is strongly suggested and warrants further investigation.
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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 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 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".