Partition of Ni between olivine and sulfide: equilibria with sulfide-oxide liquids

摘要: The partition of Ni between olivine and monosulfide-oxide liquid has been investigated at 1300–1395° C, \(f_{O_2 }\)=10−8-9−10−6.8, \(f_{S_2 }\)=10−2.0−10−0.9, over the composition range 20–79 mol. % NiS. product compositions varied from Fo98 to Fo59 0.06 3.11 wt% NiO. metal/sulfur ratio sulfide-oxide increases with increase in }\), decrease NiS content. Ni/Fe exchange reaction perfectly reversed using natural pure forsterite as starting materials. FeO NiO contents runs equilibrated same }\) form isobaric distributions content, which, a first approximation, are dependent constant temperature total pressure on variable term, −0.5 log (\(f_{S_2 }\)/\(f_{O_2 }\)). distribution coefficient (KD3) exhibits only weak 35 29 IW buffer close FMQ buffer. At values higher than FMQ, approximate (Ni,Fe)3±xS2∶KD3≈58. present KD3 vs O/(S+O) data define trend which extrapolates KD3≈20 10 oxygen liquid. Ni-Cu sulfides associated early-magmatic basic rocks komatiites consistent, 1400° value -log (\(f_{O_2 }\)/\(f_{S_2 }\)) about 7.7, is equivalent ≈0.0 hypothesized immiscible Therefore, would not be reduced significantly 30 for liquids low contents.