Details of Interaction between CaCO3 and Fe at 4 GPa and 1400‒1500°C

The issue of the stability of carbonate matter (CaCO 3 ) in subduction zones under reduced conditions remains topical. In addition, carbonates may be one of the key sources of carbon in the processes of diamond formation. The study was carried out using a high-pressure apparatus of the “split sphere” type (BARS) at a pressure of 4.0 ± 0.2 GPa and temperatures of 1400–1500°C. The interaction between CaCO 3 and Fe results in the formation of Ca–Fe oxides (Ca-wustite) and carbon-bearing iron melt due to the release of free carbon. The appearance of metallic melt segregations is the first, necessary condition for diamond crystallization in the reduced mantle domains.