Subduction signature for quenched carbonatites from the deep lithosphere

Abstract

Quenched carbonate-silicate inclusions in lherzolitic clinopyroxene macrocrysts, derived from 200 km beneath the Slave craton in northern Canada, are interpreted as natural samples of mantle carbonatites. Oxygen, carbon, and strontium isotope data provide evidence for the involvement of subducted crustal material in the origin of these carbonatites, supporting suggestions that carbon recycling by subduction is an important prerequisite for carbonatite magmatism. The compositional range of the inclusions suggests that the parent melt was decreasing in silica content as it was trapped in the host crystal, a trend that is predicted experimentally. Isotopic disequilibrium between the carbonatiti..