MODERATELY VOLATILE ELEMENTS (MVES) IN THE MARTIAN AND LUNAR MANTLES

Moderately volatile elements (MVEs) are valuable geologic tracers of high temperature events that occur during planetary formation, but are robust enough to not be reduced to below detection limit abundances in most geologic samples. The recent discovery of volatile compounds (H₂O, S, Cl, & F) in lunar material has brought a re-evaluation of the Moon forming “Giant Impact”, as well as the high temperature behavior of planetary forming materials. Volatiles in a planetary body dictate the geologic behavior of any magmas present, in addition to being key components (fuel, O₂, & H₂O) in future human planetary exploration. Issues with measuring the MVEs include: 1) They are present in very low abundance, and require a high-resolution instrument to be quantified. 2) The MVEs are susceptible to interferences from other more abundant elements present within the sample, which can artificially inflate the concentration of certain MVEs. To mitigate #1, a high-resolution inductively coupled plasma mass spectrometer was chosen for its broad chemical spectra during a single analysis, as well as its high-resolution capabilities. For #2, a series of solutions were designed to quantify, and subsequently remove the interference signal on each MVE of interest which provides a more accurate interference corrected concentration. The work presented here is the details of the method developed to quantify MVEs in lunar whole rock samples, as well as the results of 67 lunar basalt samples, 4 lunar meteorites, and 9 Martian meteorites. This geochemical data-set is the largest suite of planetary samples analyzed using the same method to allow scientific interpretation without inter-laboratory bias. The results presented here show a holistic view of not only the Earth-Moon system, but a glimpse of Mars as well. The data for the lunar samples indicates the Moon experienced a major degassing event early in its history.