Keystone area (South Dakota)
South Dakota, Black Hills, United States
Orogenic goldAu (Fe)
- Type
- Iron-formation-hosted gold
Au (Fe) deposit of Middle Proterozoic age in a dominantly clastic metasedimentary terrane, metamorphosed to amphibolite facies. Palmer and Slack (1989, Table 1): tourmaline at -13.71 ‰. Tourmalines of this kind of terrane range from -15.37 to -2.19 ‰ in the article; according to the authors, the boron source (continental crust, entrained seawater, evaporites) matters more than the formation temperature.
δ11B in ‰ (per mil) Values of the same system
Standard : NIST SRM 951
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| −13.71 ‰ | 1 | tourmaline of the massive sulfide or associated tourmalinite Single analysis (R-173-71). Uncertainties: R-173-71 -13.71 ± 0.35 ‰. | Palmer & Slack (1989), Boron isotopic composition of tourmaline from massive sulfide depo… |
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Cite this page
IsoFind Atlas (2026). Keystone area (South Dakota), isotope signatures. https://www.isofind.tech/isotopes/en/deposits/secteur-de-keystone-dakota-du-sud/ (accessed 2026-10-19).
@misc{isofind2026keystoneareasouthdakotaisotop,
title = {Keystone area (South Dakota), isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/secteur-de-keystone-dakota-du-sud/},
note = {Accessed 2026-10-19}
}Updated : 2026-10-19