THE MULTIPLE SULFUR ISOTOPIC COMPOSITION OF IRON METEORITES: IMPLICATIONS FOR NEBULAR EVOLUTION By

Title of Document: The Multiple Sulfur Isotopic Composition of Iron Meteorites: Implications for Nebular Evolution. Michael Ariel Antonelli, Master of Science, 2013. Directed By: Professor James Farquhar, Department of Geology and Earth System Sciences Interdisciplinary Center, University of MarylandCollege Park Multiple sulfur isotopic measurements of troilite from 61 different iron meteorites were undertaken in order to test for sulfur isotopic homogeneity within (and between) 8 different iron meteorite groups. It was found that different members within a given group of iron meteorites have homogeneous ΔS compositions, but that these ΔS compositions differ between groups. This thesis shows that iron meteorites from the groups IC, IIAB, IIIAB, IIIF, and IVA have small yet resolvable enrichments or depletions in ΔS relative to Canyon Diablo Troilite (CDT) and troilite from other non-magmatic (IAB and IIE) iron meteorites. The observed anomalous sulfur isotopic compositions in magmatic iron meteorites are most consistent with Lyman-α photolysis of H2S, pointing towards inheritance of an unexpected photolyticallyderived sulfur component in magmatic iron meteorite groups which is absent in nonmagmatic iron meteorites, chondrites, and the Earth-Moon System. THE MULTIPLE SULFUR ISOTOPIC COMPOSITION OF IRON METEORITES: IMPLICATIONS FOR NEBULAR EVOLUTION