The evolution of Na-Ca carbonates at HP and high to low T conditions.

The ubiquitous occurrence of Ca-Mg carbonates on Earth comes together with an intriguing paucity of (earth-)alkaline carbonatitic deposits probably due to the instability of minerals in the CaCO3-(Na,K)2CO3 system at ambient conditions and in presence of meteoric water. However, these minerals are of a great geological importance as possible lowering agents for mantle melting temperature. Moreover, Na-carbonate phases have been recently attributed to the so called “bright spots” on the surface of Ceres, a dwarf planet located on the asteroids belt. The present proposal is aimed to study by single crystal X-ray diffraction the crystal structure evolution of the anhydrous nyerereite [Na2Ca(CO3)2] and the highly water content form, gaylussite [Na2Ca(CO3)2·5H2O], at high pressure and high to low temperature conditions. Obtained results will allow to infer about the inner dynamics and composition of both the Earth and planetary bodies.