Constraining the rise of oxygen with oxygen isotopes.
- Killingsworth, Bryan A.
- Sansjofre, Pierre
- Philippot, Pascal
- Cartigny, Pierre
- Thomazo, Christophe
- Lalonde, Stefan
DOIAbstract
10 pagesInternational audienceAfter permanent atmospheric oxygenation, anomalous sulfur isotope compositions were lost from sedimentary rocks, demonstrating that atmospheric chemistry ceded its control of Earth's surficial sulfur cycle to weathering. However, mixed signals of anoxia and oxygenation in the sulfur isotope record between 2.5 to 2.3 billion years (Ga) ago require independent clarification, for example via oxygen isotopes in sulfate. Here we show <2.31 Ga sedimentary barium sulfates (barites) from the Turee Creek Basin, W. Australia with positive sulfur isotope anomalies of ∆33S up to + 1.55‰ and low δ18O down to -19.5‰. The unequivocal origin of this combination of signals is sulfide oxidation in meteoric water. Geochemical and...
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