Anniv East (Howard's Pass district)
Yukon, Selwyn Basin (Howard's Pass district), Canada
SEDEXZn-Pb
- Type
- Vent-distal Zn-Pb SEDEX in mudstones
Llandoverian (443 to 439 Ma) mineralised horizon of massive to semi-massive sphalerite and galena in calcareous and cherty mudstones of the Active Member (ACTM) of the Duo Lake Formation, over 2.6 km; 16.92 Mt indicated at 1.2 % Pb and 4.15 % Zn. Tl of unmineralised rocks follows the redox indicators (variable suboxic to euxinic conditions), that of the ore is heavier, carried by the mineralising fluids; Tl hosted by sphalerite and white mica rather than galena (Peter et al., 2018). Coordinates of drill hole ANE-108 (UTM NAD83, zone 9) converted to degrees.
ε205Tl in ε units (parts per 10,000) Values of the same system
Standard : NIST SRM 997
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| −3.2 ± 0.53 ε | −3.6 / −2.6 ε | 3 | Zn-Pb ore of the Active Member (bulk) Mean and standard deviation recalculated from 3 analyses, drill hole ANE-108 at 251, 262.2 and 271.5 m (± 0.4 to 1.1 ε); 0.81 to 3.14 ppm Tl; heaviest values, heavy hydrothermal Tl masking the redox signal. | Peter et al. (2018), Reconnaissance thallium isotope study of zinc-lead SEDEX mineralizat… |
| −4.7 ± 0.46 ε | −5.2 / −4.3 ε | 3 | unmineralised Active Member mudstones (bulk) Mean and standard deviation recalculated from 3 analyses, 252.5, 259.3 and 273 m (± 1.0 to 1.3 ε); 0.26 to 0.40 ppm Tl; redox conditions varying from one level to the next. | Peter et al. (2018), Reconnaissance thallium isotope study of zinc-lead SEDEX mineralizat… |
| −5.47 ± 1.82 ε | −7.5 / −4 ε | 3 | hanging-wall Upper Siliceous Mudstone (USMS, bulk) Mean and standard deviation recalculated from 3 analyses, 225.6, 235 and 244.9 m; 0.07 to 0.16 ppm Tl; -7.5 ± 4.4 ε just above the ore, the most uncertain value (lowest Tl), then becoming heavier upwards; suboxic to oxic deposition for the most negative values. | Peter et al. (2018), Reconnaissance thallium isotope study of zinc-lead SEDEX mineralizat… |
| −4.6 ± 0.2 ε | −4.8 / −4.4 ε | 3 | footwall Lower Cherty Mudstone (LCMS, bulk) Mean and standard deviation recalculated from 3 analyses, 275.2, 281.6 and 284 m (± 0.8 to 1.2 ε); 0.35 to 1.12 ppm Tl. | Peter et al. (2018), Reconnaissance thallium isotope study of zinc-lead SEDEX mineralizat… |
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Cite this page
IsoFind Atlas (2026). Anniv East (Howard's Pass district), isotope signatures. https://www.isofind.tech/isotopes/en/deposits/anniv-east-district-de-howard-s-pass/ (accessed 2026-10-15).
@misc{isofind2026anniveasthowardspassdistricti,
title = {Anniv East (Howard's Pass district), isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/anniv-east-district-de-howard-s-pass/},
note = {Accessed 2026-10-15}
}Updated : 2026-10-15