The origin of the fractionation of platinum-group elements in terrestrial magmas

Highly siderophile element and 182 W evidence for a partial late veneer in the source of 3.8 Ga rocks from Isua, Greenland

“…from an HSE-poor melt) would almost certainly impart HSE fractionation (see figure 7 in Szilas et al, 2015 for Isua cumulate HSE patterns) due to the differing behaviour of Os, Ir and Ru over Pt and Pd during both the low degree of partial melting required to produce an HSE-poor melt, and during subsequent magmatic evolution and accumulation (e.g. Barnes et al, 1985). For instance, none of the cumulate samples from Isua (Szilas et al, 2015), and only one of 49 cumulates from Rum, Scotland (O'Driscoll et al, 2009) and Musk Ox, Canada (Day et al, 2008) has combined Pt/Os and Ir/(Pt+Pd) (Fig.…”

Chalcophile elemental constraints on sulfide-saturated fractionation of Cenozoic basalts and andesites in SE China

“…Olivine and chromite may fractionate IPGE from PPGE, because these two minerals have different partition coefficients for these element groups (Barnes et al, 1985;Brügmann et al, 1987). Crystallization of alloys or discrete metal clusters would deplete some particular PGEs (Merkle, 1992;Peck and Keays, 1990a;Tredoux et al, 1995), whereas segregation of sulfides (Barnes and Picard, 1993;Campbell and Naldrett, 1979;Maier et al, 1996) depletes all PGEs in magmas.…”

“…Platinum-group elements (PGEs) are sensitive to sulfide saturation and silicate fractionation (e.g., Barnes et al, 1985;Barnes and Picard, 1993;Brügmann et al, 1987) and provide a powerful tool for examining the petrogenesis of mafic rocks (e.g., Keays, 1995;Lightfoot and Keays, 2005;Wang et al, 2011;Zhou, 1994). Chu et al (1999) determined the concentrations of PGEs of basalts and peridotite xenoliths from Hannuoba, NE China, and reported an extreme depletion of Ir relative to other PGEs (Fig.…”

COMPOSITION AND EVOLUTION OF PGE MINERALIZATION IN CHROMITE ORES FROM THE IL’CHIR OPHIOLITE COMPLEX (Ospa-Kitoi and Khara-Nur areas, East Sayan)

“…В дальнейшем подобные сплавы претерпели диффе-ренциацию. Твердый раствор (Os, Ru)S 2 отнесен к этой стадии на основании того, что для образования эрлик-манита требуется бóльшая активность S, чем для RuS 2 [Barnes et al, 1985], что может быть реализовано в условиях недеплетированной мантии, а при парциальном плавлении сера уходит, и в рестите остаются самородные сплавы Os-Ir-Ru, что мы и наблюдаем в хромититах истощенных дунит-гарцбургитовых комплексов [Barnes et al, 1985].…”