A deuterium-poor water reservoir in the asteroid 4 Vesta and the inner solar system

Recent investigations of meteorites thought to originate from the asteroid 4 Vesta have suggested an early accretion water on rocky bodies in inner Solar System a carbonaceous chondrite-like source. However, these studies been based hydrogen isotope compositions (δD) late-crystallizing apatite grains eucrites that likely do not record primary magmatic composition. We determined δD and H2O concentrations some earliest-formed silicates (clinopyroxenes) several with goal constraining composition their source reservoir parent body. The clinopyroxenes Juvinas, Stannern Tirhert range 5 18 μg/g, weighted average –263 ± 70‰. Their apatites whitlockites exhibit higher –165 73‰, possibly as result H2 degassing during or after phosphate crystallization. Thermal metamorphism has most probably resulted loss H, increase original values. While value for eucrite reported here is inferred reflect upper limit isotopic silicate mantle Vesta, considered be closest initial (i.e., –373 127‰), which lighter than Earth’s depleted chondrites. suggest at least (and other System) was derived relatively deuterium-poor protosolar nebula, incorporated into planetesimals formed history.