Archean emplacement of eclogitic components into the lithospheric mantle during formation of the Kaapvaal craton

Abstract

Re-Os data for selected whole-rock eclogites and eclogitic sulfide inclusions in diamonds from seven kimberlites on the Kaapvaal-Zimbabwe cratons yield ages around 3 Ga. The presence of such old eclogitic components in the subcontinental lithospheric mantle is more common than previously thought. Overlap of these ages with those of many cratonic peridotites demonstrates that incorporation of eclogitic materials accompanied or closely followed cratonic lithosphere stabilization. Many of these eclogitic components have fractionated C, N, O, and S isotopic compositions which could have been created at low-temperatures, implying that some style of Archean subduction involving emplacement of oceanic lithosphere was part of craton keel development.