Segregation of high pressure partial melts from peridotite using aggregates of diamond: A New experimental approach

Recent theoretical, observational, and experimental evidence from mid‐ocean ridges suggests that mantle permeability is large enough at small melt fractions to permit segregation of very small amounts of melt. Yet experiments to study the chemical characteristics of small partial melt fractions have not been performed. We report a new experimental technique that achieves segregation of small percentages of melt from a peridotite source using a porous layer of diamond chips adjacent to the peridotite. With this configuration, experiments were conducted using piston‐cylinder apparatus at 15 kb and 1425°C over a range of times. Melts produced by this method do not suffer from crystal growth in the melt upon quenching and, since they are direct products of melting of the peridotite source, do not contain introduced basaltic components as in sandwich techniques. We show that while melts produced in short duration runs are not in equilibrium with the residue, equilibrium is approached in the longer duration runs. This new technique may be adapted to address questions of melt generation in the mantle.