Textural and spatial relationship between platinum-group elements and alteration assemblages in the Afton porphyry system, Kamloops, British Columbia
Bibliographic record
Abstract
The Afton Cu-Au porphyry system is located near of Kamloops, B.C, Canada, and contains significant platinum-group element (PGE) enrichment.The alteration assemblages at Afton are consistent with a typical porphyry systems (phyllic, propylitic, potassic and argillic), with phyllic and propylitic being the most wide-spread and pervasive.Samples demonstrating elevated grades of Pd and Au show phyllic alteration is characterized by phengitic and paragonitic end-member dioctahedral micas (identified through NIR-IR spectroscopy and petrography).Two distinct mineralizing fluids are proposed, as phengitic micas require fluid-mobile Mg, whereas paragonitic micas will only stabilize in Mgpoor/alkali-rich fluids.However, both minerals require a fluid with a high pH.The samples demonstrate propyllitic alteration, characterized by Mg-chlorite, FeMg-chlorite, epidote and actinolite.Relative Au enrichment can show a positive correlation with Mg-chlorite.Mg-chlorite, similar to phengitic mica, requires a high pH and high Mg fluid to stabilize.Using SEM-MLA, Pd was found to be hosted within temagamite, and mertieite-II, most commonly in textural association with phengitic micas, and Mg-chlorite.3D modeling (using Leapfrog and assay data) revealed a deposit-scale negative spatial correlation between Pd and primary Cu and Au, but a secondary, structurally-controlled relationship between Pd and Au.Preliminary IR fluid inclusion and LA-ICPMS studies revealed that primary fluid inclusions hosted with hematite are coeval with Pd deposition since Pd was found in trace amounts as a dissolved species in hematite at concentrations in the 100-200 ppb range.The results of the study demonstrate that Pd deposition occurred in response to secondary hydrothermal events involving oxidizing, high pH, Mg-or alkali-rich, and chloride-rich fluids (based on mineral chemistry) operating at conditions of ~400-500 o C and above 0.5 kbar (based on phengite-biotite stability in absence of talc).Degassing of high Mg basaltic subvolcanics, now spatially associated with the porphyry stock, may have been the source of these Pd-rich fluids.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.005 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".