Controls on groundwater selenium, arsenic and base metals in groundwater around a selenium-bearing volcanogenic massive sulfide deposit: constraints from stable isotopes, trace elements and redox controls
Bibliographic record
Abstract
Understanding the controls on the behaviour of metalloids (Se, As) and metals (Cu, Zn, Pb) in natural aqueous systems is vital to interpreting hydrogeochemical data in environmental and mineral exploration applications. Geochemical, isotopic and redox measurements of a suite of groundwaters sampled from around the ABM zone of the Kudz Ze Kayah (KZK) volcanogenic massive sulfide (VMS) deposit in the Yukon, Canada are presented and contrasted with other case studies from a variety of mineral deposit types. This deposit has atypically high As (up to 4.3 wt%, average 2457 ppm) and Se (up to 2620 ppm, average 157 ppm) contents in the sulfide mineralization. As a relatively undisturbed deposit (unmined), it is an ideal site to study the mobility and solubility of trace metals in groundwaters. Herein we present field measurements (pH, dissolved oxygen, specific conductance, oxidation–reduction potential and temperature), major ion, trace element, anion (Cl, Br, SO 4 , PO 4 ), and stable isotope ( δ 2 H, δ 13 C DIC , δ 18 O, δ 18 O SO4 , δ 34 S) data. Waters are dominantly low-salinity HCO 3 to HCO 3 –SO 4 -type waters with variable sulfate (4.83 to 601 mg l −1 ), Ca (23–235 mg l −1 ) Mg (3.1–96.8 mg l −1 ), Na (0.30–66.9 mg l −1 ) and K (0.55 to 6.25 mg l −1 ) concentrations. These waters also have variable trace element concentrations that include As (0.01 to 148 µg l –1 ), Se (<0.02 to 1.01 µg l –1 ), Fe (0.01 to 3.84 mg l −1 ), Zn (<0.2 to 1070 µg l –1 ), Pb (<0.01 to 8.4 µg l –1 ), Cu (0.03 and 24.5 µg l –1 ) and Sb (0.01 to 54.4 µg l –1 ). Some waters also have elevated concentrations (compared to most meteoric waters) of Nb (up to 0.3 µg l –1 ), Y (up to 1.42 µg l –1 ), Zr (up to 18 µg l –1 ), and the rare-earth elements (REEs) ( Σ REE up to 2.04 µg l –1 ). The δ 18 O (−22.8 to −20.9 ‰) and δ 2 H (−174 to −158 ‰), together with the δ 13 C DIC (−10.6 to +1.9 ‰), δ 34 S (+10 to +12 ‰) and δ 18 O SO4 (15.5 to −4.75 ‰) all suggest that local meteoric water has interacted with massive sulfide mineralization at the ABM zone. Our results demonstrate the requirement for the use of multiple techniques in hydrogeochemical studies, with dissolved concentrations of major and trace elements coupled with a suite of stable isotopes that help define a larger geochemical footprint for the KZK deposit. Water–mineral interaction between groundwater aquifers and VMS deposits like the ABM zone are distinctly different from dispersion halos described from other deposit types (i.e. Cu porphyry, unconformity U). Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues
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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 | 0.000 | 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) | 0.000 | 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 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".