Coupling sulfur and oxygen isotope ratios in sediment melts across the Archean-Proterozoic transition

Janne Liebmann, Christopher J. Spencer, Christopher L. Kirkland, Claire E. Bucholz, Xiao Ping Xia, Laure Martin, Nami Kitchen, Leonid Shumlyanskyy

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

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 δ18O 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 Δ33S ranging from −0.29‰ to 0.13‰, whereas post-2.3 Ga granitoids record S-MDF (i.e. Δ33S = 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.

Original languageEnglish
Pages (from-to)242-257
Number of pages16
JournalGeochimica et Cosmochimica Acta
Volume307
DOIs
Publication statusPublished - 15 Aug 2021

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