The abundance and isotopic composition of water in eucrites

Abstract

Abstract Volatile elements play a key role in the dynamics of planetary evolution. Extensive work has been carried out to determine the abundance, distribution, and source(s) of volatiles in planetary bodies such as the Earth, Moon, and Mars. A recent study showed that the water in apatite from eucrites has similar hydrogen isotopic compositions compared to water in terrestrial rocks and carbonaceous chondrites, suggesting that water accreted very early in the inner solar system given the ancient crystallization ages (~4.5 Ga) of eucrites. Here, the measurements of water (reported as equivalent H 2 O abundances) and the hydrogen isotopic composition (δ D ) of apatite from five basaltic eucrites and one cumulate eucrite are reported. Apatite H 2 O abundances range from ~30 to ~3500 ppm and are associated with a weighted average δ D value of −34 ± 67‰. No systematic variations or correlations are observed in H 2 O abundance or δ D value with eucrite geochemical trend or metamorphic grade. These results extend the range of previously published hydrogen isotope data for eucrites and confirm the striking homogeneity in the H‐isotopic composition of water in eucrites, which is consistent with a common source for water in the inner solar system.