Phase relationships in the join grossularite-pyrope-7.5 percent H2O at 30 kb.

Abstract

The join was studied between 900o and 1525oC using piston-cylinder apparatus and starting materials consisting of dehydrated gels with compositions along the join Ca3Al2Si3O12-Mg3Al2Si3O12. At P of 30 kbar and with 7.5% H2O, pyrope melts incongruently introducing spinel and orthopyroxene solid solution in parts of the join. Grossular melts congruently with brackets 1500o-1522oC and 1300o-1525oC. The experimentally identified liquidus and subliquidus relations for grossular solid solution and the eclogite minerals pyrope solid solution and aluminous clinopyroxene are reported in detail and compared with results of studies in the dry system. - M.S.