Carbon Redox Chemistry: Deep Carbon Dioxide and Carbonates

Abstract

Carbon dioxide is an important terrestrial volatile, often considered to exist in deep Earth interior, and it plays a critical role in the deep carbon cycle. Yet it is not well understood whether or how such volatile carbon species are incorporated into the Earth’s lower mantle and core. Here, we present the phase/chemical diagram of carbon dioxide that signifies the transformation of molecular CO2 to extended solids, ionic carbonates, and ultimately its elemental decomposition products of C and O2. We also discuss fundamental barochemical concepts governing carbon redox processes that may occur to recycle carbonaceous species in deep Earth’s interior.