Fractional crystallization, low-degree partial melting and silicate liquid immiscibility
have been proposed as general paths that lead to the formation of granitic rocks on the
Moon.  Each of these paths has different implications for igneous evolution of the Moon
and provides a context for understanding the origin of granitic rocks on other
terrestrial planets, including the Earth, where granites comprise an essential component
of the continental crust.  

In this study, geochemical signatures of fractional crystallization (FC) and silicate
liquid immiscibility (SLI) will be inferred from sample-based work and suggested as
targets for remote sensing.  Co-magmatic clasts in the NWA 773 clan of mafic lunar
meteorites show that FC caused Fe# (Fe/[Fe+Mg]) to increase to nearly 1, followed by
SLI, resulting in ferro-basaltic and alkali-rich granitic liquids.  KREEP-rich clasts in
Apollo sample 15405 also evolved initially by FC, but underwent SLI at lower Fe#.
Therefore, (1) granitic rocks formed by SLI in KREEP-rich systems are expected to have
lower Fe# (<70) than in more mafic systems (Fe# >90), and (2) determination of Fe# by
remote sensing may provide a constraint on the origin of silica-rich igneous bodies on
the Moon.