Marshall Pass district
Colorado, Saguache and Gunnison counties, United States
UraniumU
- Type
- Fault-controlled uranium veins and breccias
Veins and breccia zones in limestones of the Belden Formation (Pennsylvanian), at the intersection of major faults with Tertiary erosion surfaces buried by siliceous tuffs, the likely uranium source. Uraninite 87Sr/86Sr measured by Balboni et al. (2016) for nuclear forensics: low ratios (below 0.7200) in low-temperature sandstone deposits, high in pegmatites, veins and breccia pipes. Indicative coordinates (Marshall Pass).
87Sr/86Sr isotope ratio, no unit Values of the same system
Standard : NIST SRM 987
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 0.73144 ± 0.000009 | 1 | vein uraninite (sample Marshall Pass1) Single analysis; value read from the Figure 7 label, 2σ uncertainty; Marshall Pass2 not analysed for Sr. | Balboni et al. (2016), Chemical and Sr isotopic characterization of North America uranium… |
Deposits of the same type
- Billiken Lode (Critchell area) United States
- Happy Jack Mine (White Canyon) United States
- Skyline Mine (Monument Valley) United States
- Cameron district (uraniferous petrified wood) United States
- Orphan Lode (Grand Canyon) United States
- Key Lake (Deilmann and Gaertner) Canada
- McArthur River (Athabasca) Canada
- Athabasca basin (unconformity uranium province) Canada
Cite this page
IsoFind Atlas (2026). Marshall Pass district, isotope signatures. https://www.isofind.tech/isotopes/en/deposits/district-de-marshall-pass/ (accessed 2026-10-15).
@misc{isofind2026marshallpassdistrictisotopesi,
title = {Marshall Pass district, isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/district-de-marshall-pass/},
note = {Accessed 2026-10-15}
}Updated : 2026-10-15