Fe‐Ni‐S melt permeability in olivine: Implications for planetary core formation

Abstract

A controversial issue in models of planetary core formation concerns whether iron‐sulfide melts in contact with silicate minerals at high temperature and pressure form permeable, percolating networks. We address this issue by determining interconnectivity and calculating the permeability of quenched olivine‐iron‐sulfide partial‐melt samples synthesized at high temperature and pressure for a range of melt fractions and two melt compositions using 3D synchrotron radiation computed tomography and lattice‐Boltzmann simulations. Permeability ranged from ∼10−19m2at the lowest concentration of melt (∼1% by volume), to ∼10−13m2at higher concentrations (∼13% by volume). Permeability as a function of melt fraction is described by a relation of the formk=αd2ϕnwith a scaling exponent n of 3.6. Our findings, considered a lower bound when compared to larger grained planetesimals, show percolation is a viable mechanism for the migration of FeS melt that may be applicable to models of planetary core formation.