9725900 Presnall Because partial melting processes in the mantle are generally understood to involve a close approach to fractional melting, it is important to obtain data on melt compositions at <2% melting. The low melt fraction limitation of studies on natural lherzolite can be overcome by using linear algebraic methods to extend the classical model system approach to systems of more than four components. This project will use this extended classical approach to study melting relations of model lherzolite in the CaO-MgO-Al2O3-SiO2-CO2 system in 3-5 GPa pressure range. All experiments will be done with a multianvil press and phase compositions will be determined with an electron microprobe. In this system, compositions of liquids produced by large to extremely small (0-2%) degrees of melting of lherzolite can be determined right down to the solidus by direct analysis, so that extrapolations from larger degrees of melting are unnecessary.
