title: Early inner solar system origin for anomalous sulfur isotopes in differentiated protoplanets.
abstract: Achondrite meteorites have anomalous enrichments in (33)S, relative to chondrites, which have been attributed to photochemistry in the solar nebula. However, the putative photochemical reactions remain elusive, and predicted accompanying (33)S depletions have not previously been found, which could indicate an erroneous assumption regarding the origins of the (33)S anomalies, or of the bulk solar system S-isotope composition. Here, we report well-resolved anomalous (33)S depletions in IIIF iron meteorites (<-0.02 per mil), and (33)S enrichments in other magmatic iron meteorite groups. The (33)S depletions support the idea that differentiated planetesimals inherited sulfur that was photochemically derived from gases in the early inner solar system (<∼2 AU), and that bulk inner solar system S-isotope composition was chondritic (consistent with IAB iron meteorites, Earth, Moon, and Mars). The range of mass-independent sulfur isotope compositions may reflect spatial or temporal changes influenced by photochemical processes. A tentative correlation between S isotopes and Hf-W core segregation ages suggests that the two systems may be influenced by common factors, such as nebular location and volatile content.
authors.affiliation: Department of Geology, University of Maryland, College Park, MD 20742; mantonelli@berkeley.edu.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Antonelli
authors.affiliation: School of Geography and Earth Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada;
authors.forename: Sang-Tae
authors.initials: ST
authors.lastname: Kim
authors.affiliation: Department of Geology, University of Maryland, College Park, MD 20742;
authors.forename: Marc
authors.initials: M
authors.lastname: Peters
authors.affiliation: Laboratoire de Géochimie des Isotopes Stables, Institut de Physique du Globe de Paris, UMR 7154 CNRS, Universite Paris Denis-Diderot, Sorbonne Paris Cite, 75005 Paris, France;
authors.forename: Jabrane
authors.initials: J
authors.lastname: Labidi
authors.affiliation: Laboratoire de Géochimie des Isotopes Stables, Institut de Physique du Globe de Paris, UMR 7154 CNRS, Universite Paris Denis-Diderot, Sorbonne Paris Cite, 75005 Paris, France;
authors.forename: Pierre
authors.initials: P
authors.lastname: Cartigny
authors.affiliation: Department of Geology, University of Maryland, College Park, MD 20742;
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Walker
authors.affiliation: School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287; and.
authors.forename: James R
authors.initials: JR
authors.lastname: Lyons
authors.affiliation: Department of Geology, University of Maryland, College Park, MD 20742;
authors.forename: Joost
authors.initials: J
authors.lastname: Hoek
authors.affiliation: Department of Geology, University of Maryland, College Park, MD 20742; Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD 20742.
authors.forename: James
authors.initials: J
authors.lastname: Farquhar
keywords: iron meteorites; photochemistry; protoplanetary disk; solar system; sulfur isotopes