Silicon carbonates may be the major host of carbon in the Earth’s mantle

Silicon is the cation with the second highest concentration the Earth’s mantle. Due to the great abundance of silicon inside the deep Earth, a hypothetical silicon carbonate synthesized at mantle conditions has to be considered for geophysical modelling of the Earth’s interior and for the Earth’s carbon budget. Our preliminary experimental Raman spectra in the silica + CO2 system show the formation of an unknown silicon carbonate after laser-heating. Here we propose to solve the crystal structure of the first silicon carbonate and to investigate the systems silica + CO2 at different pressures up to 125 GPa in diamond anvil cells using single crystal X-ray diffraction.