Nickel isotope fractionation in komatiites and associated sulfides in the hart deposit, Late Archean Abitibi Greenstone Belt, Canada

Planetary accretion and core formation inferred from Ni isotopes in enstatite meteorites

“…Hence, the δ 60/58 Ni variation in aubrites may be caused by heterogeneities in the fractions of these minerals, since Ni should have different valance states in metal (Ni 0 ) and sulfide, phosphides, and other non-metal phases (Ni 2þ ). It is known that magmatic sulfides in terrestrial komatiites can possess isotopically light δ 60/58 Ni values down to approximately −1 ‰ (Hiebert et al, 2022), however, these rocks formed at very different fO 2 compared to the highly reduced enstatite achondrites. The δ 60/58 Ni variations in ureilites may also be controlled by isotopically light sulfide, relative to metal (Zhu et al, 2022).…”

Ni isotopes provide a glimpse of Earth’s pre-late-veneer mantle

“…Despite the minimal influence of silicate partial melting or fractional crystallization on Ni isotopes, unusual and relatively large Ni isotopic fractionations up to 1.2‰ have been observed between silicates and sulfides in ultramafic-mafic magmas associated with magmatic sulfide ore deposits ( 45 – 48 ). A recent theoretical model of fractionation between komatiitic lava and sulfide melt with Ni isotopic exchange followed by sulfide crystallization predicts a range of δ 60 Ni values from +0.17‰ to −1.02‰ in sulfide-rich rocks depending on the extent of fractional crystallization and the amount of trapped melt between sulfide minerals ( 47 ). More recently, a rather large Ni isotopic fractionation with δ 60 Ni varying from +0.07 to +1.00‰ was recognized in Noril’sk basalts and can be well explained by sulfide-silicate liquid immiscibility during magmatic differentiation where light isotopes preferentially partition into the sulfide liquid ( 48 ).…”

“…S4] reflect the involvement of sulfides and/or alloys, these PGE variations and absolute PGE abundances (fig. S7) are not associated with limited change of δ 60 Ni values, still suggesting that no process such as incongruent melting, immiscibility, crystallization, or metasomatism of sulfides (44,47,48,50) has effectively affected the Ni isotopic compositions of the NUB peridotites. Although samples 208191 and 208196 have a few visible pentlandites (fig.…”

“…Despite the minimal influence of silicate partial melting or fractional crystallization on Ni isotopes, unusual and relatively large Ni isotopic fractionations up to 1.2‰ have been observed between silicates and sulfides in ultramafic-mafic magmas associated with magmatic sulfide ore deposits (45)(46)(47)(48). A recent theoretical model of fractionation between komatiitic lava and sulfide melt with Ni isotopic exchange followed by sulfide crystallization predicts a range of δ 60 Ni values from +0.17‰ to −1.02‰ in sulfide-rich rocks depending on the extent of fractional crystallization and the amount of trapped melt between sulfide minerals (47). More recently, a rather large Ni isotopic fractionation with δ 60 Ni varying from +0.07 to +1.00‰ was recognized in Noril'sk basalts and can be well explained by sulfide-silicate liquid immiscibility during magmatic differentiation where light isotopes preferentially partition into the sulfide liquid (48).…”