Publication
Iridosmine grains from placer deposits associated with peridotite-bearing ophiolites in the Klamath mountains have extremely radiogenic Os-186/Os-188 ratios and old Re-Os minimum ages, from 256 to 2644 million years. This indicates the existence of an ancient platinum group element reservoir with a supra-chondritic Pt/Os ratio. Such a ratio may be produced in the outer core as a result of inner core crystallization that fractionates Os from Pt. However, if the iridosmine Os isotopic compositions are a signature of the outer core, then the inner core must have formed very early, within several hundred million years after the accretion of Earth.
Alexandra Roma Larisa Kushnir, Michael Heap
François Maréchal, Rafael Amorim Leandro De Castro Amoedo, Julia Granacher, Mouhannad Abou Daher