Our first objective seeks to characterize the mobility of phosphorus in olivine crystals at natural concentrations and conditions relevant to the deep lunar crust/ upper mantle. Our second objective…

This is a $493,305 grant awarded by the National Aeronautics and Space Administration (NASA) to the University of Hawaii at Manoa, a land-grant, sea-grant, and space-grant public research university in Hawaii. The grant is not associated with a set-aside program.

The grant funding supports three key research objectives: 1) characterizing the mobility of phosphorus in olivine crystals in the lunar crust and upper mantle, 2) determining if the phosphorus enrichment observed in a previous study of lunar troctolite 76535 is common among Mg-suite lunar crustal rocks, and 3) evaluating the conditions leading to phosphorus uptake in olivine, the efficacy of reactive melt transport in forming Mg-suite troctolites, and the viability of proposed Mg-suite parent magmas.

This work is directly relevant to NASA's Solar System Workings program, specifically the "Surfaces and Interiors" and "Mantle Evolution" focus areas, as it aims to better understand the internal structure, chemistry, and dynamics of the Moon. The University of Hawaii has extensive experience supporting NASA through various contract and grant awards spanning planetary science, climate research, and more.

Our first objective seeks to characterize the mobility of phosphorus in olivine crystals at natural concentrations and conditions relevant to the deep lunar crust/ upper mantle. Our second objective is to determine whether the phosphorus enrichment we observed in a predecessor award focusing on troctolite 76535 is rare (or common) among members of the MG-suite of lunar crustal rocks. Our third objective is to evaluate (a) the conditions that lead to phosphorus uptake by olivine crystals, (b) the efficacy of reactive melt transport as a mechanism for the formation of MG-suite troctolite, and (c) the viability of two leading ideas for the MG-suite parent magmas. Our determination of the diffusivity of p in olivine is essential for interpreting ancient lunar rocks of the lunar crust. Determining the elapsed time these materials spent at elevated temperature is necessary to understand thermal evolution of their source region within the moon s interior. Our study of other samples in the lunar suite will establish the general relevance of troctolite 76535, which we have already examined, and which yielded surprising results. Compositional heterogeneities within crystals of olivine reveal a complex history of growth, dissolution, and RE-growth. If fine-scale enrichments of phosphorus are present in many samples, and especially if they are truncated within coherent olivine crystals (as we observe in 76535), the reactive dissolution and RE-precipitation cycle will emerge as germane to members of the lunar MG-suite the community will need to consider these processes in the context of other mgsuite rocks. Our proposed reactive infiltration experiments are aimed at understanding melt transport through crystal mush and will test the efficacy of two leading proposed parent magma compositions for generating the features we observed in 76535. This proposal is directly relevant to the solar system workings (SSW) program element, and specifically to the sections entitled surfaces and interiors and mantle evolution, which articulate, respectively, the need to "determine the internal structure, chemistry, and dynamics of solar system objects and identify and understand the physical and chemical processes that occur within these structures," and to "understand the chemical evolution and physical structure of mantles and how they change over time."