Unravelling tourmaline in mineralized porphyry systems: assessment as a valid indicator mineral
Bibliographic record
Abstract
Tourmaline has long been regarded as a petrogenetic indicator of its host environment, but its genesis in mineralized porphyry systems is poorly understood. Based on chemical and physical properties, tourmaline possesses essential features to be an effective indicator mineral. These properties, along with its abundant occurrence in mineralized copper-gold-molybdenum porphyry systems, make it potentially a key recorder of hydrothermal fluid composition, evolution and potential mineralization. A suite of tourmaline-bearing, barren and mineralized porphyry samples have been analysed as part of a broader study, including those from the Canadian Cordillera (Casino, Schaft Creek, High-land Valley and Woodjam) plus others, have been studied. Paragenetically, tourmaline is observed to be an early hydrothermal phase, predating both sulphide formation and any alteration. Tourmaline is observed to exhibit multiple growth zones, based on petrographic and electron microscope observations, which are also reflected in distinct trace-element variations. Three distinct textural types are recognized: breccia-style, vein-style and disseminated-style. Ma-jor element analyses based on SEM-EDS show a range between schorl (Na-Fe2+-rich) to dravite (Na-Mg-rich) with some minor povondraite (Na-Fe3+) component. Trace element analyses of porphyry related tourmaline via LAM-ICP-MS show distinct characteristics in comparison to that from non-porphyry settings, including redox sensitive elements (Mn, As and Sb) and large-ion lithophile elements (Sr, Ba). Elements not observed in significant concentrations include the light elements (Li, Be) and REEs, which commonly were below limit of detection. Current trace element analysis of tourmaline derived from surficial sediments points to tourmaline originating from the local porphyry system rather than an external source.
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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 | 0.000 | 0.000 |
| 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".