New Evidence for Wet Accretion of Inner Solar System Planetesimals from Meteorites Chelyabinsk and Benenitra

Abstract We investigated the hydrogen isotopic compositions and water contents of pyroxenes in two recent ordinary chondrite falls, namely, Chelyabinsk (2013 fall) Benenitra (2018 fall), compared them to three Antarctic finds, Graves Nunataks GRA 06179, Larkman Nunatak LAR 12241, Dominion Range DOM 10035. The pyroxene minerals are hydrated (?0.018–0.087 wt.% H 2 O) show D-poor signatures ( ? D SMOW from ?444‰ ?49‰). On contrary, finds exhibit evidence terrestrial contamination with elevated (?0.039–0.174 wt.%) values (from ?199‰ ?14‰). evaluated several small parent-body processes that likely alter measured inferred loss S-type planetesimals is minimal during thermal metamorphism. reflect a mixed component nebular D-rich mesostases. A total 45%–95% characterized by low was contributed hydrogen. asteroids dominantly composed nominally anhydrous can hold 254–518 ppm water. Addition dry inner solar system bodies accretion suggests reduced need volatile delivery planets late accretion.