On the Petrogenesis and Distribution of the High-Alumina Mare Basalts: An Integrated Approach Using Geochemical and Remote Sensing Data

High alumina (HA) mare basalts are an interesting and important part of the lunar sample collection. Their aluminous nature alludes to the depth and extent of source melting, differentiation within the lunar mantle, and to the efficiency of plagioclase separation during the crystallization of the Lunar Magma Ocean. They represent the oldest sampled mare basalts, and the return of HA basalt samples from four locations, separated by 2400 km, implies they may be widespread on the Moon. I analyzed several basaltic lunar samples using a combination of solution and laser ablation inductively coupled plasma mass spectrometry (ICP-MS). From these analyses and data from the literature, I constructed a petrogenic model for the Apollo 14 HA basalts. These basalts separate into three groups based on age and trace element chemistry. The group designations decrease with age in the order A to B to C. The groups also represent three magmatic events that tapped compositionally distinct source regions, which exhibit an increase in KREEP component and decrease in ilmenite in the order A to C to B. The second part of the doctoral research used compositional remote sensing data to search the whole Moon for exposures of HA mare basalts, or areas where the regolith consists mainly of material derived from HA basaltic flows. Of 34 regions of interest (ROIs) selected by the search criteria for the whole-Moon search, four were analyzed in finer detail using high-resolution (125 m/pixel) Clementine-derived FeO and TiO2 imagery. These were Mare Moscoviense, Mare Nectaris, Mare Fecunditatis, northern Mare Imbrium. Each was of the mare filling a major basin. The basaltic units for each basin were divided and characterized on the basis of their composition, spectral properties, and relative age. Each ROI was found to have at least one HA basalt unit.