Variations of the Os/Ir ratio in terrestrial rocks and minerals

Evidence for a gradual rise of oxygen between 2.6 and 2.5Ga from Mo isotopes and Re-PGE signatures in shales

“…They are similar to those of komatiites (Maier et al, 2003;Puchtel et al, 2004) and therefore indicate little or no fractionation from the source rock. Normalized Os/Ir ratios are close to unity, similar to ratios measured in a wide range of terrestrial rocks (Agiorgitis and Wolf, 1984). Re concentrations show no relative enrichment beyond that seen in komatiites.…”

Signatures of the highly siderophile elements in the SNC meteorites and Mars: a review and petrologic synthesis

“…This is because Os and Ir appear to behave rather coherently during basaltic petrogenesis (Chou et al, 1983;our Fig. 1), although it is conceivable that Os is somewhat more compatible than Ir (e.g., Agiorgitis and Wolf, 1984;Puchtel and Humayun, 2001). (In fact, most of the Os/Ir ratios summarized in our paper are either chondritic or subchondritic.)…”