Post-tilleyite, a dense calcium silicate-carbonate phase.

ABSTRACT: Calcium carbonate is a relevant constituent of the Earth's crust that is transferred into the deep Earth through the subduction process. Its chemical interaction with calcium-rich silicates at high temperatures give rise to the formation of mixed silicate-carbonate minerals, but the structural behavior of these phases under compression is not known. Here we report the existence of a dense polymorph of Ca₅(Si₂O₇)(CO₃)₂ tilleyite above 8 GPa. We have structurally characterized the two phases at high pressures and temperatures, determined their equations of state and analyzed the evolution of the polyhedral units under compression. This has been possible thanks to the agreement between our powder and single-crystal XRD experiments, Raman

SUBMITTER: Santamaria-Perez D 

PROVIDER: S-EPMC6536543 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature