Early inner solar system origin for anomalous sulfur isotopes in differentiated protoplanets

Significance This investigation focuses on the sulfur isotopic compositions of magmatically differentiated meteorites, the oldest igneous rocks in our solar system. We present evidence of anomalous 33 S depletions in a group of differentiated iron meteorites, along with 33 S enrichments in several other groups. The complementary positive and negative compositions, along with observed covariations in 36 S and 33 S, are explained by Lyman-α photolysis of gaseous H 2 S in the solar nebula. Confirmation of photochemically predicted 33 S depletions implies that the starting composition of inner solar system sulfur was chondritic, consistent with the Earth, Moon, Mars, and nonmagmatic iron meteorites. Differentiated protoplanets, however, appear to have accreted from materials processed under conditions where sulfur was volatile and UV radiation was present (<∼2 AU).

Early inner solar system origin for anomalous sulfur isotopes in differentiated protoplanets Journal Articles