Distribution of partial melt in a felsic system: the importance of surface energy

Abstract

The texture, distribution, and infiltration tendency of a quartz-albite melt in equilibrium with a synthetic, texturally-equilibrated quartzite was examined in a series of distribution and infiltration experiments at 1,250° C and 8 kbar hydrostatic pressure. Wetting angle measurements from melt distribution experiments show a dihedral angle (θ) of 60 degrees, implying a quartz/quartz interfacial energy approximately 1.7 times the quartz/melt value. Because of this specific relationship between interfacial energies, the system can achieve its lowest surface free energy state with the melt either in pools or along grain edge intersections, possibly forming some interconnected channels. Stability of melt in pockets and along grain edge intersections was observed in a fourteen-day, dispersed-melt experiment, yet melt pools failed to disperse into the quartzite during infiltration experiments. Comparison of the observed dihedral angle with previously measured surface energy values for the melt and quartz shows excellent agreement, and also demonstrates that an aggregate of randomly orientated anisotropic grains acts approximately isotropically.