Publication Date

April 2015

Advisor(s)

James Greenwood

Major

Earth and Environmental Sciences

Language

English (United States)

Abstract

Lunar samples containing indigenous water indicate that parts of the early Moon contained water concentrations similar to Earth’s mantle, but the concentrations and influences of water and other volatile chemicals during lunar evolution remain unknown. The Apollo 12 olivine basalt suite consists of an erupted and differentiated magma body, and we focus on olivine- and chromite-hosted melt inclusions from slowly cooled Apollo 12 rocks to study the volatile history of the Apollo 12 olivine basalt suite. We examined melt inclusions, which partially protect small volumes of magma from magmatic processes, in thick sections of Apollo 12 basaltic cumulates 12018, 12035, and 12040. Secondary Ion Mass Spectrometry (SIMS) analysis with modified Cameca ims 1270 and 1280 at Hokkaido University measured volatile content of melt inclusions. We mounted samples in low-temperature metal and polished without water to prevent contamination. We identified melt inclusions with optical microscopy and the scanning electron microscope at Wesleyan University. We measured F concentrations of 147 ppm, and Cl concentrations of 20 ppm inside of a chromite-ulvöspinel-hosted melt inclusion from Apollo sample 12035,76A, which exceed previously published lunar glass concentrations. Olivine-hosted melt inclusions in samples 12035,76C,E were devoid of indigenous lunar H, and lunar samples 12018,266B and 12040,216b,A2 contained D/H ratios similar to terrestrial sources. High F and Cl melt inclusions may be relicts of the terrestrial mantle and/or meteoritic delivery of volatile-rich material. H absence suggests sub-solidus diffusion after melt entrapment.

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