IPGE (Os, Ir, Ru) are not in chromite

摘要

1 IntroductionThe well-known correlations between chromitite deposits and IPGE (Os, Ir, Ru, ± Rh) enrichments (Page et al., 1982a, b; Stockman & Hlava, 1984), as well as the similar IPGE contents between mantle chromitites and crustal chromitites (Fig. 1), have led researchers to suggest that IPGE partition into chromite. The fractionation of IPGE from Pt and Pd by chromite is used in petrogenetic models of PGE-reefs.This hypothesis has been reinforced by experimentalists who demonstrate that under oxidizing conditions (fO2 > FMQ+2; FMQ: Fayalite-Magnetite-Quartz buffer) these elements can partition into spinel (Capobianco & Drake, 1990; Capobianco et al., 1994; Righter et al., 2004; Homolova et al., 2008).