Sulfur and mercury MIF suggest volcanic contributions to Earth’s atmosphere at 2.7 Ga

Aubrey Zerkle, M. W. Claire, T. Di Rocco, Nathalie Grassineau, Euan Nisbet, R. Sun, R. Yin

Research output: Contribution to journalArticlepeer-review

Abstract

The Archean eon is associated with large-scale changes in Earth’s geosphere and bio-sphere, including the onset of plate tectonics and the expansion of oxygenic photo-synthesis, although the full impacts of these changes on the atmosphere remainunclear. Here we present coupled records of mass independent fractionation of sulfur (S-MIF) and mercury (Hg-MIF) isotopes from well preserved sediments of the ∼2.7 billion year old (Ga) Manjeri Formation, Belingwe Greenstone Belt, Zimbabwe. These palaeoatmospheric proxies record different trends for S-MIF and odd number Hg-MIF versus even number Hg-MIF, providing novel constraints on atmospheric chemistry during this time. S-MIF and odd number Hg-MIF values are muted in comparison to values preserved in later Archean sediments, representing a combination of enhanced volcanic input and local mixing. Even number Hg-MIF is absent from these sediments, consistent with complete photo-oxidation of gaseous Hg0, which could have been driven by increased halogen emissions from arc volcanism. When considered within a global geo-dynamic context, these MIF data suggest an important role for subduction zone-related volcanism associated with early platetectonics in modulating the ∼2.7 Ga atmosphere.
Original languageEnglish
Pages (from-to)48-52
Number of pages5
JournalGeochemical Perspectives Letters
Volume18
DOIs
Publication statusPublished - 9 Sep 2021

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