The Osmium Isotope Perspective on the Dynamics of the Post-Archean Mantle

The ¹⁸⁷Re–¹⁸⁷Os system offers a unique perspective among the isotopic approaches used to understand planetary evolution because of the chalcophile and siderophile affinities of the parent and daughter elements and their contrasting behaviors during partial melting. Considered the geochronometer of choice to study the Earth’s mantle, from the scale of individual minerals to large-scale outcrops, this system has revealed the survival of Archean and Proterozoic mantle in younger tectonic settings, and has demonstrated local to regional coupling, and sometimes decoupling, between the crust and mantle. Osmium isotopes are also key tracers of melt–peridotite and mantle–crust interactions and recycling processes in subduction zones, and have furthered our understanding of the origin of multi-scale geochemical and isotopic heterogeneities.