Textural, mineralogical, lithogeochemical and lead and thallium isotopic characterization of magmatic rocks in Selwyn Basin, Yukon: potential spatial and temporal linkages with lead-zinc mineralisation
Bibliographic record
Abstract
Alkaline to subalkaline magmatic rocks in the Selwyn Basin, Yukon may provide evidence of a genetic link to clastic sediment-hosted Pb-Zn deposits in the Anvil and MacMillan Pass districts. To examine if such a link is present, we document the petrography, lithogeochemical, and thallium isotopic compositions of magmatic rocks in these regions. Anvil District volcanic rocks are interpreted as basaltic effusive eruptions and phreatomagmatic surge and/or fall deposits, whereas samples from the MacMillan Pass district were emplaced by explosive eruptive activity. The MacMillan Pass samples contain large amounts of ankerite and calcite. Earn Group metavolcanic rocks from the Keno Hill area have few primary textures to identify eruption dynamics. This group is crosscut by a series of Triassic mafic dikes that exhibit little alteration or deformation. Samples of Marmot Volcanics from the Misty Creek Embayment are effusive basalts. Magmatism is alkaline in all regions except for Keno Hill, where both the Earn Group metavolcanic rocks and Triassic dikes are subalkaline. Six samples from the MacMillan Pass District have epsilon-205Tl values of -3.2 ± 1.8 to -14.2 ± 3.2. Five samples from the Anvil District have epsilon-205Tl values of 0.9 ± 1.9 to -6.4 ± 1.2. These preliminary data will be supplemented with additional analyses of mineralised horizons and host shales to investigate the link between high Ba and Tl contents in both the volcanic rocks and SEDEX deposits. Future work will constrain age relationships between mineralized samples and volcanism, use Pb, Sr and Nd to constrain magma sources and use Tl, Mo and potentially Ba isotopes to examine the link between mineralisation and magmatism.
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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 | 0.001 |
| 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) | 0.001 | 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".