Coupling sulfur and oxygen isotope ratios in sediment melts across the Archean-Proterozoic transition. (15th August 2021)

• Record Type: Journal Article
• Authors: Liebmann, Janne; Spencer, Christopher J.; Kirkland, Christopher L.; Bucholz, Claire E.; Xia, Xiao-Ping; Martin, Laure; Kitchen, Nami; Shumlyanskyy, Leonid
• Is Part Of: Geochimica et cosmochimica acta. Volume 307(2021)
• Page Start: 242
• Page End: 257
• Publication Date: 2021-08-15
• Subjects: Atmospheric oxygenation -- Great Oxygenation Event -- Continental emergence -- Archean Proterozoic boundary -- Oxygen Isotopes -- Multiple sulfur isotopes -- S-type granites -- Strongly peraluminous granites; Geochemistry -- Periodicals; Meteorites -- Periodicals; Géochimie -- Périodiques; Météorites -- Périodiques; Geochemie; Astrochemie; Electronic journals; 551.905
• DOI: 10.1016/j.gca.2021.05.045
• Languages: English
• ISSNs: 0016-7037

Abstract

Abstract: The Archean-Proterozoic transition marks a time of fundamental geologic, biologic, and atmospheric changes to the Earth system, including oxygenation of the atmosphere (termed the Great Oxygenation Event; GOE), and the emergence of continents above sea level. The impacts of the GOE on Earth's surface environment are imprinted on the geologic record, including the disappearance of mass-independent fractionation of sulfur isotopes (S-MIF). Temporally overlapping geologic and geochemical observations (e.g. a change in oxygen isotope ratio of sediments and an increase in subaerial volcanism) imply the widespread subaerial emergence of continents was coeval with atmospheric oxygenation. Here we present triple sulfur isotope ratios in pyrite and oxygen isotope ratios in garnet and zircon in a global suite of Archean and Proterozoic granitoids derived from the partial melting of sedimentary protoliths. These crustal melts record an increase in average garnet and zircon δ 18 O from 7.2‰ before 2.3 Ga to 10.0‰ post-2.3 Ga. Pre-2.3 Ga granitoids show small S-MIF signatures with Δ 33 S ranging from −0.29‰ to 0.13‰, whereas post-2.3 Ga granitoids record S-MDF (i.e. Δ 33 S = 0‰). The combination of sulfur and oxygen isotope signatures in the same sample with zircon U-Pb geochronology provides new insights on a potential causal link between the emergence of continents and Paleoproterozoic atmospheric oxygenation.