Understanding the Geochemical Evolution of an Asymmetric Moon

Introduction: Major ambiguities remain in our current understanding of the geochemical evolution of the moon. That situation arises partly because (a) our geochemical and isotopic data sets for mare basalts are overly influenced by samples from the Procellarum KREEP Terrain (PKT [1]), and (b) samples of the highland crust useful for isotopic studies are limited in both quantity and quality. Future missions returning lunar samples should target those areas likely to contain mare basalts not influenced by the PKT, and/or a suite of crustal samples most likely to faithfully reveal the processes of lunar crustal formation. Figure 2. Estimated source Rb/Sr for lunar basalts vs. longitude of known or estimated sampling sites. Lunar Basalts