Late-Stage Low-Temperature Hydrothermal Alteration Overprint at the East Zone in the Red Chris Porphyry Cu-Au Deposit, Northwestern British Columbia, Canada
Bibliographic record
Abstract
Abstract High- and intermediate-temperature alteration assemblages at the East zone in the Red Chris porphyry Cu-Au deposit, northwestern British Columbia, Canada, are varyingly overprinted by a lower-temperature intermediate argillic alteration assemblage composed of illite-kaolinite-hematite-carbonate. The intermediate argillic assemblage extensively overprinted the upper 600 m of the porphyry deposit and is present discontinuously to depths of 1,500 m below the premining surface. Kaolinite is dominant in shallow levels and gradually diminishes with depth, replaced by illite as the dominant clay mineral. Hematite replaced hydrothermal and igneous magnetite, but the intensity diminishes with depth. Mixtures of ankerite, dolomite, siderite, and calcite replaced mafic silicates and formed veins. Oxygen and hydrogen isotopes confirm a magmatic fluid source for the potassic assemblages preserved at depth as well as for the overprinted phyllic assemblage in the upper part and flanks of the East zone. In contrast, the superposed intermediate argillic assemblages formed by a mixture of magmatic and meteoric fluids. Sulfide minerals and sulfur isotopes retain zonal patterns for porphyry Cu deposits and appear largely unaffected by the overprinted intermediate argillic assemblage. Carbon and oxygen isotopes in carbonate vary with depth that may reflect a thermal gradient as a rising fluid cooled. The intermediate argillic assemblage is spatially associated with and overprinted on as yet undated late monzodioritic dikes—the youngest phase in the host Late Triassic Red stock. The relative age relationships and stable isotopic geochemistry indicate the intermediate argillic alteration assemblage represents the flux of magmatic-derived hydrothermal fluid that mixed with external fluid and thus represents either the last fluid pulse in the porphyry Cu deposit or a younger, temporally distinct hydrothermal fluid.
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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 | 0.003 |
| 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) | 0.002 | 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".