Petrography, mineralogy and initial fluid inclusion results from the Jason, Tom, and Nidd SEDEX deposits, Macmillan Pass District, Yukon
Bibliographic record
Abstract
Sediment-hosted base metal mineralization in the Selwyn Basin occurs during 3 time intervals in the Cambrian, Silurian and Late Devonian, coeval with magmatic episodes. At Macmillan Pass, the Tom, Jason and Nidd showings are hosted by Upper Devonian sediments and have well preserved vent complexes beneath overlying bedded sulphides (Tom, Jason). Core was sampled from the vent complexes at Tom, Jason, and Nidd. Detailed petrography (reflected and transmitted light and cathodoluminescence), was conducted to characterize the mineralogy within the vent complex, and the relationship of fluid inclusion bearing mineral phases to base metal sulphides. Microthermometry (Tom and Nidd) and bulk incremental fast scan gas mass spectrometry (Nidd) was performed on fluid inclusion samples. Carbon, oxygen and sulphur isotopes were analysed on mineral separates to determine the source of these components in each system. The petrography indicates that for all three localities, fluid flow in the vent can be split in two distinct stages. Stage 1 is dominated by extensive stock-work style iron carbonate veining, along with destructive carbonate and pyrite alteration. Base-metal sulphides are deposited during Stage 2, in association with a volumetrically minor gangue assemblage (siderite, quartz ± barite, barytocalcite and quartz). Initial fluid inclusion results indicate the presence of a CO2-bearing assemblage at Nidd, which has preserved evidence of phase immiscibility. The N2-Ar-He bulk composition of these samples suggests the involvement of a deep calc-alkaline magmatic reservoir. Microthermometric results from Tom indicate the presence of low (120-130°C) and intermediate (170-235°C) temperature fluids; only one salinity measurement was obtained from the intermediate temperature fluid, which yielded a value of 7.9 wt.% NaCl. Delta-34S (VCDT) values have a broad range from -12.6 permille to 20.5 permille, and two sphalerite-galena pairs suggest equilibrium fractionation may have occurred between 366-388°C; delta-13C (V-PDB) have a restricted range from -0.5 permille to -8.6 permille, apart from two groups of outliers that are either highly negative (-20 permille and -12.4 permille) or highly positive (13.3 permille and 14.3 permille); delta-18O (V-SMOW) range between 13.6 permille to 20.5 permille.
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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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".