EFFECT OF CARBONATES ON CRYSTALLIZATION AND COMPOSITION OF POTASSIUM-BEARING CLINOPYROXENE AT HIGH PRESSURES

Abstract

It was stated for the first time that clinopyroxene containing >1 wt % K2O may crystallize at 1300–1700°C and 5–11 GPa from carbonate liquid containing 14–33 wt % K2O. KCpx with as much as 5.75 wt % K2O was obtained in experiments as a product of melt crystallization in the Di–Grs–K2CO 3 and Di–Grs–K2Mg(CO 3)2 systems at 7 GPa and 1500–1600°C.* Such high K2O concentrations in Cpx in carbonate–silicate systems suggest a substantial influence of carbonates on incorporation of potassium into clinopyroxenes at high pressures.