Native Metals and Alloys in Trachytes and Shoshonite from the Continental United States and High-K Dacite from the Bolivian Andes: Magmatic Origins of Ore Metals in Convergent and Within-Plate Tectonic Settings
Bibliographic record
Abstract
Nb-rich trachytes from Virginia, shoshonite from Colorado and high-K dacite from the Bolivian Andes contain diverse suites of native metals and alloys. Virginia trachytes are differentiates of mafic within-plate magmas derived from oceanic island basalt (OIB)-type mantle sources in the post-orogenic extensional regime of the Appalachian mobile belt. Colorado shoshonite and Bolivian dacite were produced via crystal fractionation of Fe–Mg silicates from trachybasalt and basalt magma, respectively, derived from subduction-related mantle modified by either crustal contamination (both regions are underlain by thick, mature continental-type crust) or recycling of marine sediment. Metal assemblages include refractory metals (Pt with minor Fe and Cr, native W, Co–W and Fe–W alloys), Cu–Ag–Au alloys, chalcophile metals (Cu–Sn alloy, native Cu and Zn) and associated sulfides (galena). Textural evidence (metals occur as inclusions in phenocrysts, high temperatures of their formation, etc.) and compositional features of metallic phases suggest their magmatic origin. Metal-rich magmas (both mafic and differentiated) transport metals in convergent and within-plate tectonic settings and deliver ore metals to the oxidized porphyry and epithermal environments in the upper crust.
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How this classification was reachedexpand
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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 teacher head, 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".