Smith Ranch-Highland mine unit MU4a groundwater
Wyoming, Converse County, M sand of the Fort Union Formation, United States
Groundwater
- Type
- Groundwater
Ring of monitoring wells up- and down-gradient of an orebody already mined by in situ recovery, and ore-zone wells (2012-2014). Up-gradient water (11 to 16 µg/L U, 234U/238U from 5.1 to 5.6) loses heavy uranium crossing the orebody: down-gradient, below 10 µg/L, δ238U from -2.8 to -1.5 ‰ and 234U/238U below 3.7, except in two wells (M452, M458) without a reduction signal. Natural attenuation by U(VI) reduction, useful for post-mining restoration planning (Brown et al., 2016). Coordinates not given.
δ238U in ‰ (per mil) Values of the same system
Standard : CRM 145
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| −0.91 ± 0.08 ‰ | −1.08 / −0.82 ‰ | 9 | groundwater up-gradient of the orebody (dissolved uranium) Mean and standard deviation recalculated from 9 analyses, wells M431, M432, M434, M436 to M439, M442 and M446; 11.4 to 16.3 µg/L U; δ238U already lower than most known waters and silicates. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| −1.57 ± 0.39 ‰ | −1.95 / −1.17 ‰ | 3 | groundwater of wells adjacent to mine unit MU4a (dissolved uranium) Mean and standard deviation recalculated from 3 analyses, wells M419, M402 (250 m from the orebody) and M403 (512 m); 2.0 to 9.1 µg/L U; depletion increasing with distance from the orebody. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| −2.04 ± 0.41 ‰ | −2.81 / −1.73 ‰ | 6 | groundwater down-gradient of the orebody, reduced wells (dissolved uranium) Mean and standard deviation recalculated from 6 analyses, wells M450, M453, M454, M455A (two samplings) and M456, 190 to 264 m from the orebody; 2.8 to 11.1 µg/L U; uranium depleted in 238U by U(VI) reduction in the orebody. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| −0.53 ± 0.13 ‰ | −0.62 / −0.43 ‰ | 2 | groundwater down-gradient of the orebody, wells M452 and M458 (dissolved uranium) Mean and standard deviation recalculated from 2 analyses, 15.1 and 30.0 µg/L U; no reduction signal, excluded from the trend by the authors; values close to the up-gradient water. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| −0.1 ± 0.24 ‰ | −0.41 / 0.15 ‰ | 4 | ore-zone groundwater after mining (dissolved uranium) Mean and standard deviation recalculated from 4 analyses, wells MP423, MP425, MP430 and P80-H-4-4; 13.6 to 40.1 mg/L residual U; oxidised uranium from the dissolution of U oxides during mining. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
(234U/238U) isotope ratio, no unit Values of the same system
Standard : équilibre séculaire
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 5.45 ± 0.15 | 5.12 / 5.61 | 9 | groundwater up-gradient of the orebody (dissolved uranium) Mean and standard deviation recalculated from 9 analyses, same nine wells as δ238U; high, clustered ratios due to α recoil and silicate weathering, with no correlation with U content. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| 5.15 ± 0.81 | 4.57 / 5.722 | 2 | groundwater of wells adjacent to mine unit MU4a (dissolved uranium) Mean and standard deviation recalculated from 2 analyses, M419 and M402, M403 not measured. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| 3.31 ± 0.4 | 2.9 / 3.709 | 5 | groundwater down-gradient of the orebody, reduced wells (dissolved uranium) Mean and standard deviation recalculated from 5 analyses, M450, M453, M454, M455A and M456, second M455A sampling not measured; ratio intermediate between up-gradient and ore zone: water leaves the orebody near equilibrium then regains 234U by α recoil down-gradient. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| 2.79 ± 0.64 | 2.34 / 3.25 | 2 | groundwater down-gradient of the orebody, wells M452 and M458 (dissolved uranium) Mean and standard deviation recalculated from 2 analyses, M452 and M458; low ratios despite an unreduced δ238U. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| 1.04 ± 0.1 | 0.97 / 1.11 | 2 | ore-zone groundwater after mining (dissolved uranium) Mean and standard deviation recalculated from 2 analyses, MP423 and P80-H-4-4; close to secular equilibrium. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
δ34S in ‰ (per mil) Values of the same system
Standard : V-CDT
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| −11.2 ± 0.36 ‰ | −11.62 / −10.75 ‰ | 7 | groundwater up-gradient of the orebody (dissolved sulphate) Mean and standard deviation recalculated from 7 analyses, seven up-gradient wells, M434 and M439 not measured; 91 to 157 mg/L SO4. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| −11.55 ± 2.2 ‰ | −13.11 / −10 ‰ | 2 | groundwater of wells adjacent to mine unit MU4a (dissolved sulphate) Mean and standard deviation recalculated from 2 analyses, M419 and M403, the latter published to the nearest unit. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| −10.58 ± 0.38 ‰ | −10.85 / −10.14 ‰ | 3 | groundwater down-gradient of the orebody, reduced wells (dissolved sulphate) Mean and standard deviation recalculated from 3 analyses, M454 and M455A (two samplings); 68 to 110 mg/L SO4, sulphate slightly heavier than up-gradient: limited sulphate reduction. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| −10.23 ± 0.04 ‰ | −10.26 / −10.21 ‰ | 2 | groundwater down-gradient of the orebody, wells M452 and M458 (dissolved sulphate) Mean and standard deviation recalculated from 2 analyses, M452 (125 mg/L SO4) and M458 (98 mg/L). | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| −14.61 ± 0.72 ‰ | −15.12 / −14.1 ‰ | 2 | ore-zone groundwater after mining (dissolved sulphate) Mean and standard deviation recalculated from 2 analyses, MP423 (896 mg/L SO4 according to the text) and P80-H-4-4 (810 mg/L); light sulphate from sulphide oxidation during mining. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
δ18O in ‰ (per mil) Values of the same system
Standard : V-SMOW
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| −4.06 ± 0.73 ‰ | −5.34 / −3.07 ‰ | 7 | groundwater up-gradient of the orebody (dissolved sulphate) Mean and standard deviation recalculated from 7 analyses, seven up-gradient wells, M434 and M439 not measured. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| −0.89 ± 2.9 ‰ | −2.94 / 1.16 ‰ | 2 | groundwater of wells adjacent to mine unit MU4a (dissolved sulphate) Mean and standard deviation recalculated from 2 analyses, M419 and M403. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| −3.1 ± 0.39 ‰ | −3.53 / −2.79 ‰ | 3 | groundwater down-gradient of the orebody, reduced wells (dissolved sulphate) Mean and standard deviation recalculated from 3 analyses, M454 and M455A (two samplings); distribution less systematic than δ34S according to the authors. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| −3.78 ± 4.02 ‰ | −6.62 / −0.94 ‰ | 2 | groundwater down-gradient of the orebody, wells M452 and M458 (dissolved sulphate) Mean and standard deviation recalculated from 2 analyses, M452 and M458, the extreme values of the monitoring ring, both down-gradient. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
| −8.39 ± 2.55 ‰ | −10.19 / −6.59 ‰ | 2 | ore-zone groundwater after mining (dissolved sulphate) Mean and standard deviation recalculated from 2 analyses, MP423 and P80-H-4-4. | Brown et al. (2016), Isotopic evidence for reductive immobilization of uranium across a r… |
Deposits of the same type
- Vinto drinking water (DW1 to DW3) Bolivia
- Coal-mine tip, site 1 (unconfined chalk aquifer) France
- Coal-mine tip, site 2 (confined chalk aquifer) France
- Pebble deposit seeps United States
- Yarlung Tsangpo basin geothermal springs China
- Archibarca alluvial fan groundwater Argentina
- Rosario River fan hot springs Argentina
- Jiangling Basin thermal waters (JS-W1, YC-W1) China
Cite this page
IsoFind Atlas (2026). Smith Ranch-Highland mine unit MU4a groundwater, isotope signatures. https://www.isofind.tech/isotopes/en/sites/eau-souterraine-de-l-unite-miniere-mu4a-de-smith-ranch-highland/ (accessed 2026-10-15).
@misc{isofind2026smithranchhighlandmineunitmu4,
title = {Smith Ranch-Highland mine unit MU4a groundwater, isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/sites/eau-souterraine-de-l-unite-miniere-mu4a-de-smith-ranch-highland/},
note = {Accessed 2026-10-15}
}Updated : 2026-10-15