9506045 Johnston This project involves a three-year experimental research program on the near-solidus melting behavior of a range of peridotites, varying both the compositional fertility of their constituent minerals and the modal abundances of these minerals. A specific focus will be determining the stoichiometry of the solidus reaction for different peridotites and the manner in which the stoichiometry of the melting reaction changes at super-solidus temperatures. The study will involve various combinations of pure mineral separates from natural peridotite xenoliths, with several mixtures intentionally enriched in spinel and/or clinopyroxene to enhance the signal imparted by these phases on the melting process. the near-solidus melting behavior of these mixtures will then be investigated using the diamond aggregate experimental technique.