Experimental study of the basalt-carbonate-H2O system at 4 GPa and 1100-1300A degrees C: Origin of carbonatitic and high-K silicate magmas

摘要

Generation of K-silicate and carbonatite melts by melting of carbonated eclogite has been studied experimentally under hydrous and dry conditions at 4 GPa and 1100-1300A degrees C. At 1100A degrees C, K-silicate melt appears first in equilibrium with Grt, Cpx, and Cb in the H2O-bearing system. At 1200-1250A degrees C, the K-silicate melt coexists with a carbonatite melt and Cpx +/- Grt +/- Cb assemblage. A complete miscibility between the K-silicate and carbonatite melts with formation of supercritical silicate-carbonate fluid melt is observed at 1300A degrees C.