Date of Award
Doctor of Philosophy (PhD)
Lunar samples are the “ground truth” that anchor our knowledge of lunar geology. Lunar rocks present many challenges in that they are often brecciated (composed of multiple rock types), and their location of formation on the Moon is not always known. The brecciated nature of lunar samples also has advantages – multiple lithologies that have a related petrogenetic history can occur in the same sample, allowing us to trace the petrogenetic history of evolving magmatic systems. In this dissertation, I examine two evolved magmatic systems, using samples from the Northwest Africa (NWA) 773 clan of lunar meteorites and Apollo 12 sample 12013. The NWA 773 clan is a group of twelve meteorites that are known, through bulk composition and mineral chemistry, to be geochemically and petrogenetically related. This work uses samples of six of these meteorites: NWA 773, NWA 2727, NWA 3160, NWA 3170, NWA 7007, and NWA 10656. These meteorites are variably composed of four lithologies (olivine gabbro, anorthositic gabbro, ferroan gabbro, olivine phyric basalts) and an immature regolith breccia. These lithologies represent a unique opportunity to study an inferred magma chamber on the Moon with both intrusive and extrusive lithologies. This work details the petrography and mineral chemistry of the intrusive lithologies and, through petrologic modeling, explores the possibility that they formed along a common liquid line of descent. Apollo 12 sample 12013 is a polymict breccia that is broadly composed of dark and light breccias. This work uses instrumental neutron activation analysis to determine that the 12013 system is a three-component system that includes a granitic component, a rare earth element - rich component, and a mafic component. Each of these three components has a distinctive petrography and geochemistry, which are explored here in order to determine their parent lithologies and petrogenesis. This work discusses the possibility that the three components of 12013 are related in a highly evolved magmatic system on the lunar surface either through silicate liquid immiscibility, bimodal volcanism, or a combination of both.
Chair and Committee
Bradley Jolliff & Randy Korotev
Robert F. Dymek, Ryan C. Ogliore, Jill D. Pasteris,
Valencia, Sarah, "The Evolution of Igneous Rocks on the Moon: Insights from Lunar Meteorites and Apollo 12" (2017). Arts & Sciences Electronic Theses and Dissertations. 1150.