Investigation of tourmaline characteristics in bedrock and surficial sediment samples from two Canadian porphyry copper systems
Bibliographic record
Abstract
Colour, texture, and chemistry were used to determine the source of tourmaline grains in local surficial (detrital) sediments from two Canadian porphyry systems (Woodjam and Casino). Tourmaline from porphyry bedrock is generally dark brown to black. Crystals frequently exhibit oscillatory and sector zoning, with overgrowth, irregular, and patchy patterns. Major-element analyses show ranges from schorl (Fe2+-rich; 0.04-3.07 apfu, av. 0.76) to dravite (Mg-rich, av. 2.00 apfu), with a minor povondraite (Fe3+) component. The alkali- and alkaline-earth element concentrations are relatively constant, with Na>Ca>_ and OH->O2- dominant. Tourmaline in porphyry systems is characterized by high Cu (tens of parts per million) and Sr (hundreds of parts per million), and low Pb (<10 parts per million) and Zn (tens of parts per million). Detrital tourmaline occurs as euhedral grains and contains similar Fe and Mg concentrations and textural zonation patterns to porphyry tourmaline. Its trace-element content shows similarities but with larger ranges of values, likely related to the presence of non-porphyry detrital tourmaline. Overall, a combination of physical and chemical characteristics (oxy-dravite-povondraite trend, high Sr, low Zn and Pb) of tourmaline grains are useful in discriminating between porphyry- versus non-porphyry-derived (or related) tourmaline in both bedrock and surficial sediments.
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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 | 0.003 | 0.003 |
| Science and technology studies | 0.002 | 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".