Hydrothermal Alteration Revealed by Apatite Luminescence and Chemistry: A Potential Indicator Mineral for Exploring Covered Porphyry Copper Deposits
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Bibliographic record
Abstract
<p>Apatite is a common resistate mineral occurring in a range of host rocks and ore-related hydrothermal alteration assemblages. Apatite in several porphyry copper deposits in British Columbia has a unique set of physical and compositional characteristics that can be used to evaluate the chemical conditions of magmas that formed the causative intrusions or associated hydrothermal alteration.</p><p>Apatite under visible light and SEM shows no notable variations between unaltered and altered varieties but cathodoluminescence reveals significant differences. Apatite in unaltered rocks displays yellow, yellow-brown, and brown luminescence, whereas in K silicate-altered rocks apatite displays a characteristic green luminescence. The green-luminescent apatite replaces yellow- or brown-luminescent apatite and locally overgrows it. Apatite occurring with muscovite (i.e., phyllic)-altered rocks displays characteristic gray luminescence.</p><p>The chemistry of apatite, as determined by electron microprobe and laser ICP-MS analyses, directly reflects its alteration and luminescence. The unaltered yellow-luminescent apatite has high concentrations of Mn (0.30.5 wt % MnO) and a high Mn/Fe ratio (>1), whereas the brown-luminescent apatite has low Mn, but higher concentrations of S and REE + Y. The green K silicate alteration-related luminescence is caused by lower Mn/Fe ratios (ca. 1) along with depletions of other trace elements such as Cl, S, and Na. Gray-luminescent apatite occurring with muscovite-altered rocks results from significant Mn loss (<0.15% MnO) contemporaneous with depletion in Na, S, Cl, and REE during low pH phyllic alteration in calc-alkalic porphyry deposits.</p><p>The correlation between apatite texture, luminescence, and chemical composition with the type and intensity of porphyry alteration offers a potentially fast and effective method to utilize it as an indicator for porphyry mineralization in a range of exploration materials including soils, regoliths, and heavy mineral concentrates from glacial and fluvial materials.</p></section>
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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 it