Synthesis of K- and Fe-rich davemaoite.

Abstract The type material of davemaoite, CaSiO3-perovskite, contains several at-% of Fe, Al, Na, and K which has potential implications for the distribution of alkalines and the Urey number of the deep mantle. Previous experiments have not shown such high alkaline contents in davemaoite and it was questioned if the type material actually formed in the deep mantle. However, these studies did not explore compositions similar to that material. We show that glass of a composition close to that of type davemaoite transforms to a homogenous perovskite-phase at 22 GPa. This finding supports correlation of Na+K with Ca and ferric Fe in deep mantle rock. The perovskite-type solid solution is volumetrically favored by ∼2% over a mixture of calcium-ferrite type oxides and endmember davemaoite.