View article

We have performed reaction experiments between 1, 4, and 5 wt % CO₂‐bearing MORB‐eclogite (recycled oceanic crust)‐derived low‐degree andesitic partial melt and fertile peridotite at 1375°C, 3 GPa for infiltrating melt fractions of 25% and 33% by weight. We observe that the reacted melts are alkalic with degree of alkalinity or Si undersaturation increasing with increasing CO₂ content in reacting melt. Consequently, an andesite evolves through basanite to nephelinite owing to greater drawdown of SiO₂ from melt and enhanced precipitation of orthopyroxene in residue. We have developed an empirical model to predict reacted melt composition as a function of reacting andesite fraction and source CO₂ concentration. Using our model, we have quantified the mutual proportions of equilibrated melt from andesite‐peridotite (+ CO₂) hybridization and subsequent peridotite (± CO₂)‐derived melt required to …