Geology of the guano-guayes rare earth element bearing Skarn property, Pelly Mountains, Yukon Territory
Bibliographic record
Abstract
The Guano-Guayes property, in the Pelly Mountains of the Yukon Territory, covers a rare earth element (REE) bearing contact metamorphic aureole which developed around a syenite stock during Mississippian time (319 ± 10 Ma phlogopite K-Ar date, 333 ± 10 Ma Rb-Sr skarn mineral isochron). Sedimentary rocks consist of several hundred metres of Ordovician dark gray shale which are faulted upward adjacent to 450 m of Silurian interbedded impure calcite and dolomite marbles and quartzites overlain by at least 500 m of Silurain quartzite. Sedimentary rocks are on the steeply, west-dipping limb of a regional anticline (the axis bears 162 degrees and plunges 24 degrees south). The syenite, at the southeast end of a northwest-trending belt of syenite stocks and associated volcanic rocks, consists of 40 to 90 percent orthoclase in laths up to several cm long, and of up to 60 percent mafic minerals now mostly altered to biotite. Rare earth element values of syenite, when normalized to chondritic values, have a crustal pattern with magnitude slightly higher than that of crustal rocks. Dikes, believed to be cogenetic with syenite, intrude sedimentary rocks within and inear the contact metamorphic aureole. These dikes are dark-coloured and originally contained up to 25 percent zircon (now partly altered to secondary minerals). Zircon is enriched in total REE and relatively enriched in light REE compared to syenite, probably due to selective partitioning of REE. REE patterns in skarn and sedimentary rocks suggest that fluids circulated through syenite and carried trace amounts of REE from it into the skarn. There was no significant movement of REE from dikes into skarn or sedimentary rocks. Contact metamorphic rocks can be divided into three units: quartz-muscovite hornfels, dark green diopsade-calcite-phlogopite-tremdlite-sphene skarn, and light green diopside-calcite-phlogopite skarn. Depth at time of intrusion of syenite, as estimated from regional geologic contraints, was around 1 to 2 km (circa 500 bars). Parageneses and textures observed in thin section in contact metamorphic rocks indicate that prograde metamorphism at this pressure reached a maximum temperature of 450 to 540 degrees C, with heat being transferred from the intrusive dominantly by fluids. The mole fraction of CO₂ in metamorphic fluids, increased By the liberation of CO₂ during prograde metamorphic reactions, was moderate. Large amounts of Fe, Mg, and possibly Si0₂, were added to the skarn. Retrograde metamorphism involved significant addition of water to the system, proven by the appearance of secondary epidote, chlorite, and, later, serpentine. Extensive retrograde metamorphism accompanied by large-scale migration of elements through syenite ended 206 ±15 Ma ago (syenite whole-rock isochron) and the last resetting event took place between 156 ± 5 Ma (K-Ar date on biotite-altered arfvedsonite) and 128 ± 25 Ma (syenite mineral isochron). Petrology, geochronometry, and rare earth element studies presented here have contributed to an understanding of the genesis of syenite, skarn, and mineralized dikes within the Guano-Guayes area.
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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 | 0.000 | 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 | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".