Conditions and extent of volatile loss from the Moon during formation of the Procellarum basin

Abstract

Rocks from the lunar interior are depleted in moderately volatile elements (MVEs) compared to terrestrial rocks. Most MVEs are also enriched in their heavier isotopes compared to those in terrestrial rocks. Such elemental depletion and heavy isotope enrichments have been attributed to liquid–vapor exchange and vapor loss from the protolunar disk, incomplete accretion of MVEs during condensation of the Moon, and degassing of MVEs during lunar magma ocean crystallization. New Monte Carlo simulation results suggest that the lunar MVE depletion is consistent with evaporative loss at 1,670 ± 129 K and an oxygen fugacity +2.3 ± 2.1 log units above the fayalite-magnetite-quartz buffer. Here, we propose that these chemical and isotopic features could have resulted from the formation of the putative Procellarum basin early in the Moon’s history, during which nearside magma ocean melts would have been exposed at the surface, allowing equilibration with any primitive atmosphere together with MVE loss and isotopic fractionation.

The Extent, Nature, and Origin of K and Rb Depletions and Isotopic Fractionations in Earth, the Moon, and Other Planetary Bodies

“…The degree of depletion for K and Rb calculated here (Figure 4, Table 1) is thus relevant to at least the upper 400 km of the Moon. Tartèse et al (2021) argued for a preferential depletion of MVEs in the near side by a large impact in the Procellarum region, which is not supported by available data. Furthermore, the GRAIL results show that Procellarum is most likely not an impact structure (Andrews-Hanna et al 2014).…”

“…To assess whether K depletion was a global feature or was biased by the sampling of the Procellarum region by the Apollo mission as was recently suggested by Tartèse et al (2021), we mapped the K/Th ratio of the Moon using data from Lunar Prospector (Lawrence et al 1998;Feldman et al 1998), and we compiled K, La, and U data of lunar meteorites from the lunar meteorite compendium. As shown in Figure 6, the K/Th ratio is the same on the near and far sides.…”

Mechanical properties of minerals in lunar and HED meteorites from nanoindentation testing: Implications for space mining

“…A meteorite subjected to high‐impact events may have more refined crystal sizes due to shock‐induced recrystallization, potentially enhancing its hardness and Young's modulus. Similarly, a meteorite that has undergone thermal annealing may display altered mechanical properties due to the depletion of moderately volatile phases (Tartèse et al., 2021). Therefore, while the elemental composition provides some insights, the mechanical history of these meteorites likely plays a crucial role in defining their current mechanical properties.…”

Large Carbonaceous Chondrite Parent Bodies Favored by Abundance–Volatility Modeling: A Possible Chemical Signature of Pebble Accretion

“…Our model allows us to calculate the vapor fraction of any element at any temperature, provided that the remainder of the conditions are consistent with those for which the original T 50% values were derived. In theory, this approach can be used to extrapolate the fraction of condensate using any data set (e.g., Lodders 2003;Fegley & Schaefer 2010) and starting from any percent (e.g., the T 99% of Tartèse et al 2021), provided that the correct tau value can be determined.…”