Chemical and isotopic composition of zircon from the Wolverine district massive sulfide deposit Yukon, Canada
Bibliographic record
Abstract
The Wolverine polymetallic volcanic hosted mass sulfide deposit (VHMS), located in the Finlayson Lake District, Yukon, Canada, contains 6,237,000 tonnes of precious metals that includes 12.66% Zn, 1.33% Cu, 1.55% Pb, 370.9 g/t Ag, and 1.76 g/t Au. The deposit is preferentially associated with ~352 Ma quartz-feldspar porphyry (QFP) and ~347 Ma feldspar porphyry (FP) intrusions, that underlie the massive sulfide lens. Whole rock geochemical data, and in particular REE and HFSE illustrate the FP suite contains higher HFSE and REE and higher Nb/Ta ratios relative to the QFP suite. These have been interpreted to represent varying crustal and mantle contributions within an evolving Mississippian continental back-arc basin. New in situ LA-Q-ICPMS U–Pb and LA-MC-ICPMS Lu–Hf isotopic data from zircon from the two porphyries suggests the presence of a deep crustal source. Inherited zircon cores identified in both the QFP and FP suite have ages ranging between 1.0 Ga to 2.0 Ga. The Lu–Hf analyses, that were done directly on top of the U–Pb analyses in the zircon grains, in the QFP averaged an eHf value of -12.4, compared to the FP which have an average eHf value of -6.7. These inherited zircon cores were either derived locally from recycled basement sources that have Neoproterozoic crust, and/or regionally with material from the Wopmay Orogen to Paleoproterozoic ages from the North American cratonic basement; which could make up the underlying basement rock of the Finlayson Lake District. The zircon Hf data for both porphyries have negative eHf values indicating a crustal source, but with the FP containing a higher eHf value suggesting a greater interaction with the mantle when comparing it to the QFP. This supports the evolving back-arc basin model for the Finlayson Lake District, with the regional extensional tectonics generating mafic magma at the base of the crust. This mantle driven heat would have melted the overlying crust, generating first the QFP, which were derived predominantly from crustal sources and had more negative eHf. With continued basin opening, mantle upwelling, and crust-mantle mixing, there was a decrease in the amount of crustal material and an increased mantle component leading to a higher eHf in the FP suite. These results are consistent with mantle heat and basaltic upwelling being important in the generation of VMS.
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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 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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 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".