Constraining the rise of oxygen with oxygen isotopes

Type Article
Date 2019-10
Language English
Author(s) Killingsworth B. A.1, 3, Sansjofre P.1, 5, Philippot P.2, 3, Cartigny P.3, Thomazo C.4, Lalonde Stefan1
Affiliation(s) 1 : Univ Bretagne Occidentale, European Inst Marine Studies, CNRS, UMR6538,Lab Geosci Ocean, F-29280 Plouzane, France.
2 : Univ Montpellier, CNRS, UMR 5243, Geosci Montpellier, Montpellier 5, France.
3 : Univ Paris Diderot, Sorbonne Paris Cite, CNRS, Inst Phys Globe Paris,UMR 7154, F-75005 Paris 05, France.
4 : Univ Bourgogne Franche Comte, CNRS, UMR uB 6282, Lab Biogeosci, 6 Bd Gabriel, F-21000 Dijon, France.
5 : Sorbonne Univ, Inst Mineral Phys Mat & Cosmochim, Museum Hist Nat, CNRS,UMR 7590, F-75005 Paris, France.
Source Nature Communications (2041-1723) (Nature Publishing Group), 2019-10 , Vol. 10 , N. 4924 , P. 10p.
DOI 10.1038/s41467-019-12883-2
WOS© Times Cited 4
Abstract

After 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 Delta S-33 up to +1.55% and low delta O-18 down to -19.5%. The unequivocal origin of this combination of signals is sulfide oxidation in meteoric water. Geochemical and sedimentary evidence suggests that these S-isotope anomalies were transferred from the paleo-continent under an oxygenated atmosphere. Our findings indicate that incipient oxidative continental weathering, ca. 2.8-2.5 Ga or earlier, may be diagnosed with such a combination of low delta O-18 and high Delta S-33 in sulfates.

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