Mineral records of magma storage and crystallization on the Moon

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The Moon preserves a remarkable record of volcanism on a small rocky terrestrial planet. Lunar lavas were mainly erupted between ~4.35 and 3 billion years ago, with some areas of the Moon being volcanically active as recently as a billion years ago. The lunar lavas were sourced by partial melts from different regions of the lunar mantle, giving rise to a range of geochemical affiliations and crystallization histories. Different lunar magma compositions are thought to have reached the lunar surface via different storage and crystallization pathways, but the pressures and temperatures of magma storage and crystallization are not well known. The aim of this project is therefore to develop new mineral-melt thermobaromers in order to investigate the record of magma storage and crystallization on the Moon. We seek to answer questions such as: Did the lunar magmas stall and crystallize in crustal mush chambers, or did they ascend rapidly from the melting region to the surface? At what pressures and temperatures did crystals nucleate and grow? What can crystal records tell us about subsurface magmatic systems and volcanic eruption styles on rocky planets? The project will exploit recent advances in mineral-melt thermobarometers calibrated for terrestrial magmas to develop new clinopyroxene-melt and olivine-melt thermobarometers that are specifically calibrated for the Na-poor magma compositions and highly reducing conditions relevant to the Moon and rocky asteroids such as Vesta. We will then apply these new methods to suites of lunar lavas sampled by the Apollo astronauts to gain new insights into the architecture of lunar magmatic systems.