EXPERIMENTAL INVESTIGATION OF CARBONATE-SILICATE LIQUID IMMISCIBILITY WITH APPLICATIONS TO THE FORMATION OF BARIUM-STRONTIUM CARBONATITES

Abstract

Liquid immiscibility in sodium- and potassium-enriched carbonate-silicate and sulfate-carbonate-silicate systems was experimentally studied at T = 1250°C and P = 2 kbar in the context of the problem of barium-strontium carbonatite genesis. The experiments confirmed the existence of an immiscibility field between silicate and salt (carbonate or sulfate-carbonate) melts under the given conditions. The investigation of barium and strontium partitioning between immiscible phases in the systems studied showed that they are accumulated in the salt melts. It was shown that the experimental carbonate and sulfate-carbonate liquids were heterogeneous, which suggests that the salt phase may undergo further evolution after its separation from silicate melt. The experimentally observed regularities are consistent with those revealed in natural carbonatite complexes.