Highly Siderophile Element and Osmium Isotope Compositions of Pristine Lunar Crust and Impact-Contaminated Rusty Rocks

The Moon’s plagioclase-rich crust is considered to have formed early in its history (>4.3 Ga) from a magma ocean. Anorthosites and associated rocks that are thought to form much of the ancient crust preserve evidence for crystallization and post-crystallization events. Unravelling the processes affecting lunar crustal rocks, however, is complex and includes consideration of effects such as vapor condensation. As part of a larger study, our goal is to better understand the relationship of crystallization and post-crystallization processes acting on the lunar crust. Here we examine the relationship of impact processes, KREEP enrichment and ‘rust’ that can occur in some Apollo 16 lunar crustal samples.