A three end-member model for petrologic analysis of lunar prospector gamma-ray spectrometer data

We analyze preliminary Lunar Prospector gamma-ray spectrometer data. Al-Mg and Fe-Mg petrologic maps of the Moon show that Mg-rich rocks are located in Mare Frigoris, the South Pole Aitken basin, and in some cryptomaria. Analysis of distances of Lunar Prospector pixels from three end-member plane in Mg-Al-Fe space reveals existence of Ca-rich, Al-low small-area anomalies in the farside highlands. An Mg-Th-Fe petrologic technique can be used for estimation of abundances of ferroan anorthosites, mare basalts, KREEP basalts, and Mg-rich rocks.