Reaction of a granitic melt with fluorine and phosphorus enriched fluids at H-O-C conditions

摘要

Melting of granitic compositions with high fluorine and phosphorus concentrations in a complex H-O-C fluid results in depolymerization of the melt structure. This may trigger the devleopment of layered solidification textures observed in the quench experiments. Quartz formed during the experiment enriched the middle zone of the capsules, whereas the lower zone is impoverished in quartz. The upper zone is free of quartz and characterized by micrographic intergrowth textures and abundant dendrites at the upper-middle zone transition. The experiment also produced berlinite and roundish-grained aggregates of nonstoichiometric composition. The SiO_2-rich melt was allocated in the middle part of the capsule during the superliquidus evolution which resulted in crystallization of quartzs after quenching.