Fluid and chemical constraints on sphalerite precipitation in the Boundary Zone Zn-Pb prospect, Yukon, Canada
Bibliographic record
Abstract
Sphalerite (ZnS) is the main ore mineral in clastic-dominant (CD-type) massive sulfide deposits. However, the precise physicochemical conditions of ore formation are often poorly constrained. This study uses sphalerite mineral chemistry and fluid inclusion microthermometry to constrain conditions of Zn mineralization at the Boundary Zone prospect of Macmillan Pass district, Canada. The sulfide mineralization comprises pyrite, sphalerite, galena, and minor chalcopyrite. Sphalerite with contrasting trace element compositions is hosted in Late Ordovician-Early Silurian (Duo Lake Formation) and Late Devonian (Portrait Lake Formation) black mudstones. Different paragenetic stages of sphalerite formation preserve distinct trace element patterns within and between host rock intervals, and overall, Ge, Ga, Cu, and Cd, are relatively enriched compared to In. Trace element incorporation mechanisms vary, with both direct and coupled substitution (e.g., 3Zn<sup>2+</sup> ↔ (Ge)<sup>4+</sup> + 2Cu<sup>+</sup>) pathways suggestive of compositional and fluid temperature differences during sphalerite precipitation. Homogenization temperatures (<em>T</em><sub>h</sub>) of CO<sub>2</sub>-N<sub>2</sub>-bearing, 2-phase primary aqueous fluid inclusions in Portrait Lake sphalerite range between 154 – 249°C (median= 179°C). The <em>T</em><sub>h</sub> values of quartz-hosted CO<sub>2</sub>-N<sub>2</sub>-H<sub>2</sub>S-CH<sub>4</sub>-bearing aqueous inclusions from late veins are in the range of 207 – 236°C (median= 223°C). These temperatures are consistent with sphalerite trace element geothermometry (GGIMFis; 163 – 279°C) and are comparable to nearby Tom and Jason CD-type deposits in the Macmillan Pass district.
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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 | 0.002 | 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) | 0.001 | 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".