Experimental model for alkalic chloride-rich liquids in the upper mantle

In order to expand an applicability of a model for evolution of the alkalic chloride-rich liquids in the upper mantle additional runs in chloride–carbonate–silicate systems involving model silicate end-members were performed at 5 GPa. Results of experiments can be evaluated using the single scheme of phase relations. They show that interaction of the chloride–carbonate liquids with silicates produces a wide range of the chloride-rich carbonate–silicate melts, whose composition is determined by the chloride/carbonate ratio in the chloride–carbonate liquid and composition of the interacting silicate assemblage. The carbonate–silicate melts are immiscible with Si–Al-saturated chloride–carbonate melts. With decreasing temperature, evolution of both melts proceeds toward the homogeneous chloride–carbonate or carbonatitic liquid coexisting with silicates. Trends for melt evolution in the model systems closely reproduce the evolution of the carbonate–silicate and saline inclusions in kimberlitic diamonds. These trends suggest a diamond growth during cooling. In addition, experiments showed stronger effect of interaction of eclogite-related phases with the alkalic chloride–carbonate melts, in contrast to peridotite-related phases.