MINERALOGICAL AND GEOCHEMICAL STUDY OF THE TRUE BLUE AQUAMARINE SHOWING, SOUTHERN YUKON
Bibliographic record
Abstract
Aquamarine of distinctly dark blue color was discovered during the summer of 2003 in the Pelly Mountains, southern Yukon Territory, Canada. The beryl is found within quartz veins that fill sigmoidal tension gashes, which cut a syenite of Mississippian age. The True Blue showing is differentiated from other beryl occurrences in the northern Cordillera by the color of the beryl, the host rock, mineral associations, timing, and mineralizing fluid. The syenite was emplaced within an extensional setting into undeformed Paleozoic sediments of the Cassiar Platform and felsic volcanic rocks of the Pelly Mountain Volcanic Belt. Post-late-Triassic tectonics resulted in a number of northeasterly directed thrust panels that were subsequently cut by Cretaceous granitic magmatism. Accessory minerals in the veins include siderite, ankerite, allanite-(Ce), fluorite, and minor albite, sulfides, and Fe–Ti–Nb oxides. Electron-microprobe analyses of beryl ( n = 192) revealed that FeO values range up to 5.92 wt.%, Na 2 O up to 2.66 wt.%, MgO up to 3.42 wt.%, CaO up to 0.11 wt.%, and H 2 O (calculated) up to 3.10 wt.%, whereas little to no Cr or V was detected. The darkest blue examples of beryl also have the highest concentrations of FeO. The allanite-(Ce) contains up to 26 wt.% REE 2 O 3 , and exhibits Fe 2+ > Fe 3+ . The fluorite that coprecipitated with beryl from several veins has been dated using Sm–Nd geochronology at 171.4 ± 4.8 Ma. In situ and whole-mineral δ 18 O values of the beryl and whole-mineral δ 18 O values of the quartz are variable; temperature estimates derived from these data suggest fluid temperatures between ~275 and ~400°C. Fluid-inclusion data from quartz, beryl, and fluorite suggest variable but high salinity (~6 to 24 wt.% NaCl equivalent) and CH 4 -absent mineralizing fluids. Conventional models to explain the formation of gem beryl, and consequently exploration parameters, applied in Yukon involve late-stage magmatic fluids. Evidence gathered in this study points to a metamorphic origin for the mineralizing fluid and a local derivation of vein constituents, which distinguish the fluids at True Blue from other intrusion- related beryl-forming fluids in the northern Cordillera.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 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) | 0.000 | 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".