The objectives of the proposed research are to experimentally determine the abundance, role and gas-melt partitioning behavior of various volatile species in lunar magmas. This objective is…

This is a $293,684.92 grant awarded by NASA to Brown University to conduct research on the abundance, role, and gas-melt partitioning behavior of volatile species in lunar magmas. The research aims to improve understanding of the evolution of the lunar surface and crust, which is a key objective of NASA's Solar System Workings (SSW) program for the Moon. The grant will fund three main tasks: (1) experiments to determine how other volatile species partition into early CO-rich vs. late H2O-rich gases during lunar picritic glass eruptions, (2) experiments to study the role of volatiles in the composition and eruption of lunar mare basalts, and (3) experiments to understand the effect of dissolved water on the origin and evolution of silica-enriched lunar magmas. This award is not associated with a set-aside program.

The objectives of the proposed research are to experimentally determine the abundance, role and gas-melt partitioning behavior of various volatile species in lunar magmas. This objective is fundamental to understanding evolution of the lunar surface and the lunar crust, a major objective of the NASA SSW program for the moon. Completed work has indicated that C is dissolved as CO (125 PPM at 200 MPA; C activity =1) and small amounts of CH4 in lunar picritic glasses that contain ~1000 PPM dissolved water. We now propose the following tasks. (1) experiments to determine how other anions (S, CL, F) and volatile cations partition into the early CO-rich gas VS. A late H2O-rich gas formed during lunar picritic glass eruptions. This data is essential when attempting to make volatile abundance estimates for picritic melts produced at depth in the moon using analyses from partially degassing samples. (2) experiments to determine CO solubility in lunar low- and high-TI mare basalt compositions at lunar FO2S and lunar crustal pressures to evaluate the role of volatiles in explaining the composition and eruption style of mare basalts VS. The picritic glass magmas using new melt inclusion data as a guide. In task (3), we propose to determine the effect of dissolved H2O on the origin and evolution of silica-enriched magmas such as those proposed for the viscous lunar lava domes (red spots). These experiments will be done on kreep-rich lunar magma compositions such as A15 kreep basalt and QMD (quartz monzodiorite) to determine evolved lunar magma compositions that can be produced by crystal-liquid fractionation as a function of P and XH2O, and the range of lunar crustal depths where silicate liquid immiscibility is encountered. The partitioning of elements between immiscible silicate liquids will be determined for these various evolved compositions, as will characteristic IR and raman spectra for variably crystallized samples for comparison with remotely sensed data, and data for natural samples.