Juomasuo
Northeastern Finland, Kuusamo belt, Finland
Orogenic goldAu-Co
- Type
- Atypical orogenic Au-Co
Deposit of the Palaeoproterozoic Kuusamo belt (2.37 Mt at 4.6 g/t Au and 0.13 % Co, plus 5.04 Mt of Co resources), in an albitized volcano-sedimentary sequence deformed and metamorphosed at greenschist facies during the Svecofennian orogeny (1.93 to 1.76 Ga). Two ore types: Co-only with pyrrhotite (stage 1, chlorite alteration, reduced metamorphic fluid) and Au-Co with pyrite (stage 2, sericitization, more oxidized fluid). Vasilopoulos et al. (2021): sulphide δ34S from -2.6 to +7.1 ‰; tourmaline consistent with evaporite-related fluids.
δ11B in ‰ (per mil) Values of the same system
Standard : NIST SRM 951
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| −18 / −11 ‰ | low-δ11B tourmaline (type 1b schorl cores and one type 3 core) Range only. Range from the results; the discussion gives -16 to -11 ‰. Probable relics of tourmaline older than albitization. | Vasilopoulos et al. (2021), Geochemical signatures of mineralizing events in the Juomasuo… | ||
| −5 / 6 ‰ | tourmaline of altered albitites (types 1 to 4, dravite) Range only. Range from the results; the discussion gives -5 to +7 ‰. Rims generally heavier than cores, by up to 10 ‰, except for type 4. | Vasilopoulos et al. (2021), Geochemical signatures of mineralizing events in the Juomasuo… |
δ34S in ‰ (per mil) Values of the same system
Standard : V-CDT
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| −2.6 / 7.1 ‰ | sulphides (pyrite, pyrrhotite and chalcopyrite) Overall range, most values between +2 and +5 ‰; a few pyrites and pyrrhotites from -2.6 to +0.9 ‰. | Vasilopoulos et al. (2021), Geochemical signatures of mineralizing events in the Juomasuo… | ||
| 3.8 ‰ | 1.2 / 6.8 ‰ | pyrite of high Co/Ni zones Published mean and range. | Vasilopoulos et al. (2021), Geochemical signatures of mineralizing events in the Juomasuo… | |
| 2.4 ‰ | −2.6 / 4.7 ‰ | pyrite of low Co/Ni zones Published mean and range; all negative pyrite values. | Vasilopoulos et al. (2021), Geochemical signatures of mineralizing events in the Juomasuo… | |
| 2 / 6 ‰ | chalcopyrite Approximate range from the text, all values positive. | Vasilopoulos et al. (2021), Geochemical signatures of mineralizing events in the Juomasuo… |
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- Kalgoorlie (Golden Mile) Australia
- Victorian Goldfields Australia
- Ashanti (Obuasi) Ghana
- Loulo (district de Gara-Yalea) Mali
- Gounkoto Mali
- Massawa Senegal
- Kirkland Lake (Macassa mine) Canada
Cite this page
IsoFind Atlas (2026). Juomasuo, isotope signatures. https://www.isofind.tech/isotopes/en/deposits/juomasuo/ (accessed 2026-10-20).
@misc{isofind2026juomasuoisotopesignatures,
title = {Juomasuo, isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/juomasuo/},
note = {Accessed 2026-10-20}
}Updated : 2026-10-20