Babbitt (Duluth Complex)
Minnesota, Duluth Complex (Partridge River troctolite), United States
Magmatic (Ni-Cu-PGE, carbonatites)Cu-Ni (EGP)
- Type
- Magmatic Ni-Cu sulphides (country-rock contamination)
Duluth Complex (Midcontinent Rift, about 1.1 Ga), Partridge River troctolite (Troctolitic Series: troctolite, peridotite, norite, olivine gabbro) intrusive into the Anorthositic Series; host rocks are graphitic, locally sulphidic pelitic metasediments of the Virginia Formation, above the Biwabik Iron Formation and the Giant's Range batholith. Mostly disseminated ore (2 to 3 % sulphides) with pyrrhotite, chalcopyrite, cubanite and minor pentlandite, Cu:Ni about 4-5:1, near the basal contact and Virginia Formation xenoliths. North-east of Dunka Road: massive to semi-massive zones more common, PGE over four times more concentrated, norite far more abundant than troctolite (silica input). Over 80 % of igneous rocks in ore zones have anomalous δ18O; pyrrhotite of Virginia Formation hornfels is lighter (+1.5 to +6.2 ‰) than over 95 % of ore sulphides: crustal sulphur acquired before or during magma ascent, and fractionation between a Cu-rich sulphide liquid (δ34S > 9 to 10 ‰) and the residual liquid (6 to 10 ‰) according to Ripley (1986). Coordinates not given.
δ18O in ‰ (per mil) Values of the same system
Standard : V-SMOW
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 5.4 / 12.1 ‰ | igneous rocks (whole rock and mineral separates) Range from the text, mode at +7 to +7.5 ‰; over 80 % of ore-zone rocks anomalous, normal rocks (+5.5 to +7.0 ‰) in patches. | Ripley (1986), Application of Stable Isotopic Studies to Problems of Magmatic Sulfide Ore… | ||
| 7.53 ± 1.25 ‰ | 5.8 / 9.1 ‰ | 7 | troctolites enclosing two hornfels xenoliths Mean and standard deviation recalculated from 7 analyses, profiles at localities 1 (279.8 to 285.9 m) and 2 (516.0 to 535.8 m); δ18O decreasing away from the contact. | Ripley (1986), Application of Stable Isotopic Studies to Problems of Magmatic Sulfide Ore… |
| 11.09 ± 1.47 ‰ | 8.4 / 14.1 ‰ | 13 | Virginia Formation xenolith hornfels Mean and standard deviation recalculated from 13 analyses, same profiles; up to 5 ‰ difference over 2 m (varied protoliths and interaction with the magma). | Ripley (1986), Application of Stable Isotopic Studies to Problems of Magmatic Sulfide Ore… |
δ34S in ‰ (per mil) Values of the same system
Standard : V-CDT
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 1.5 / 6.2 ‰ | pyrrhotite of Virginia Formation hornfels Range from the text, lower than over 95 % of ore sulphides. | Ripley (1986), Application of Stable Isotopic Studies to Problems of Magmatic Sulfide Ore… | ||
| 6 / 10 ‰ | sulphides of low-grade ore (below 1 % Cu) Range from the text (Figures 9 and 10); overall mean and range close to Dunka Road. | Ripley (1986), Application of Stable Isotopic Studies to Problems of Magmatic Sulfide Ore… | ||
| sulphides of high-grade ore (over 1 % Cu) Lower bound from the text (above 9 ‰, above 10 ‰ in the Figure 10 legend): fractionation between Cu-rich sulphide liquid and residual liquid according to the author. | Ripley (1986), Application of Stable Isotopic Studies to Problems of Magmatic Sulfide Ore… |
Deposits of the same type
- Bayan Obo China
- Norilsk-Talnakh Russia
- Bushveld, Merensky Reef South Africa
- Bushveld, UG2 chromitite South Africa
- Bushveld, Platreef South Africa
- Sudbury Canada
- Voisey's Bay Canada
- Rössing Namibia
Cite this page
IsoFind Atlas (2026). Babbitt (Duluth Complex), isotope signatures. https://www.isofind.tech/isotopes/en/deposits/babbitt-complexe-de-duluth/ (accessed 2026-10-14).
@misc{isofind2026babbittduluthcomplexisotopesi,
title = {Babbitt (Duluth Complex), isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/babbitt-complexe-de-duluth/},
note = {Accessed 2026-10-14}
}Updated : 2026-10-14