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Low marine sulphate and protracted oxygenation of the Proterozoic biosphere.
Nature. 2004 Oct 14; 431(7010):834-8.Nat

Abstract

Progressive oxygenation of the Earth's early biosphere is thought to have resulted in increased sulphide oxidation during continental weathering, leading to a corresponding increase in marine sulphate concentration. Accurate reconstruction of marine sulphate reservoir size is therefore important for interpreting the oxygenation history of early Earth environments. Few data, however, specifically constrain how sulphate concentrations may have changed during the Proterozoic era (2.5-0.54 Gyr ago). Prior to 2.2 Gyr ago, when oxygen began to accumulate in the Earth's atmosphere, sulphate concentrations are inferred to have been <1 mM and possibly <200 microM, on the basis of limited isotopic variability preserved in sedimentary sulphides and experimental data showing suppressed isotopic fractionation at extremely low sulphate concentrations. By 0.8 Gyr ago, oxygen and thus sulphate levels may have risen significantly. Here we report large stratigraphic variations in the sulphur isotope composition of marine carbonate-associated sulphate, and use a rate-dependent model for sulphur isotope change that allows us to track changes in marine sulphate concentrations throughout the Proterozoic. Our calculations indicate sulphate levels between 1.5 and 4.5 mM, or 5-15 per cent of modern values, for more than 1 Gyr after initial oxygenation of the Earth's biosphere. Persistence of low oceanic sulphate demonstrates the protracted nature of Earth's oxygenation. It links biospheric evolution to temporal patterns in the depositional behaviour of marine iron- and sulphur-bearing minerals, biological cycling of redox-sensitive elements and availability of trace metals essential to eukaryotic development.

Authors+Show Affiliations

Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee 37996, USA. lckah@utk.eduNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

15483609

Citation

Kah, Linda C., et al. "Low Marine Sulphate and Protracted Oxygenation of the Proterozoic Biosphere." Nature, vol. 431, no. 7010, 2004, pp. 834-8.
Kah LC, Lyons TW, Frank TD. Low marine sulphate and protracted oxygenation of the Proterozoic biosphere. Nature. 2004;431(7010):834-8.
Kah, L. C., Lyons, T. W., & Frank, T. D. (2004). Low marine sulphate and protracted oxygenation of the Proterozoic biosphere. Nature, 431(7010), 834-8.
Kah LC, Lyons TW, Frank TD. Low Marine Sulphate and Protracted Oxygenation of the Proterozoic Biosphere. Nature. 2004 Oct 14;431(7010):834-8. PubMed PMID: 15483609.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Low marine sulphate and protracted oxygenation of the Proterozoic biosphere. AU - Kah,Linda C, AU - Lyons,Timothy W, AU - Frank,Tracy D, PY - 2003/10/24/received PY - 2004/08/20/accepted PY - 2004/10/16/pubmed PY - 2004/12/16/medline PY - 2004/10/16/entrez SP - 834 EP - 8 JF - Nature JO - Nature VL - 431 IS - 7010 N2 - Progressive oxygenation of the Earth's early biosphere is thought to have resulted in increased sulphide oxidation during continental weathering, leading to a corresponding increase in marine sulphate concentration. Accurate reconstruction of marine sulphate reservoir size is therefore important for interpreting the oxygenation history of early Earth environments. Few data, however, specifically constrain how sulphate concentrations may have changed during the Proterozoic era (2.5-0.54 Gyr ago). Prior to 2.2 Gyr ago, when oxygen began to accumulate in the Earth's atmosphere, sulphate concentrations are inferred to have been <1 mM and possibly <200 microM, on the basis of limited isotopic variability preserved in sedimentary sulphides and experimental data showing suppressed isotopic fractionation at extremely low sulphate concentrations. By 0.8 Gyr ago, oxygen and thus sulphate levels may have risen significantly. Here we report large stratigraphic variations in the sulphur isotope composition of marine carbonate-associated sulphate, and use a rate-dependent model for sulphur isotope change that allows us to track changes in marine sulphate concentrations throughout the Proterozoic. Our calculations indicate sulphate levels between 1.5 and 4.5 mM, or 5-15 per cent of modern values, for more than 1 Gyr after initial oxygenation of the Earth's biosphere. Persistence of low oceanic sulphate demonstrates the protracted nature of Earth's oxygenation. It links biospheric evolution to temporal patterns in the depositional behaviour of marine iron- and sulphur-bearing minerals, biological cycling of redox-sensitive elements and availability of trace metals essential to eukaryotic development. SN - 1476-4687 UR - https://www.unboundmedicine.com/medline/citation/15483609/Low_marine_sulphate_and_protracted_oxygenation_of_the_Proterozoic_biosphere_ L2 - https://doi.org/10.1038/nature02974 DB - PRIME DP - Unbound Medicine ER -