COMPLICATIONS TO CARBONATE MELT MOBILITY DUE TO THE PRESENCE OF AN IMMISCIBLE SILICATE MELT

Abstract

The relative interfacial energies of immiscible carbonate and silicate melts were investigate in olivine and clinopyroxene matrices. Carbonate melt has a higher melt–solid interfacial energy than does the coexisting silicate melt. The silicate melt therefore selectively wets the grain-edge channels between solid phases, excluding the carbonate melt to the center of melt pockets, away from grain edges. This prevents the carbonate melt from migrating independently of the silicat melt and the carbonate melt is unable to separate from the silicate melt in a solid-dominated assemblage. The carbonate melt will migrate effectively only after the silicate melt has solidified or by separating from the silicate melt within liquid-dominated reservoirs (sills, dikes, or chambers), unrestricted by solid interfaces. This relative wetting behavior may help explain the close association of carbonate and silicate magmas in alkali complexes, and their relative timing of emplacement. These results also place constraints on the generation and separation of derivative melts in carbonated silicate melt systems and on the style and timing of alkali wall-rock metasomatism.