Article abstract


Nature Geoscience 3, 647 - 652 (2010)
Published online: 22 August 2010 | doi:10.1038/ngeo942

Subject Categories: Palaeoclimate and palaeoceanography | Biogeochemistry

Pervasive oxygenation along late Archaean ocean margins

Brian Kendall1, Christopher T. Reinhard2, Timothy W. Lyons2, Alan J. Kaufman3, Simon W. Poulton4 & Ariel D. Anbar1,5


The photosynthetic production of oxygen in the oceans is thought to have begun by 2.7 billion years ago, several hundred million years before appreciable accumulation of oxygen in the atmosphere. However, the abundance and distribution of dissolved oxygen in the late Archaean oceans is poorly constrained. Here we present geochemical profiles from 2.6- to 2.5-billion-year-old black shales from the Campbellrand–Malmani carbonate platform in South Africa. We find a high abundance of rhenium and a low abundance of molybdenum, which, together with the speciation of sedimentary iron, points to the presence of dissolved oxygen in the bottom waters on the platform slope. The water depth on the slope probably reached several hundred metres, implying the export of O2 below the photic zone. Our data also indicate that the mildly oxygenated surface ocean gave way to an anoxic deep ocean. We therefore suggest that the production of oxygen in the surface ocean was vigorous at this time, but was not sufficient to fully consume the deep-sea reductants. On the basis of our results and observations from the Hamersley basin in Western Australia, we conclude that the productive regions along ocean margins during the late Archaean eon were sites of substantial O2 accumulation, at least 100million years before the first significant increase in atmospheric O2 concentration.

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  1. School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287, USA
  2. Department of Earth Sciences, University of California, Riverside, California 92521, USA
  3. Department of Geology and Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland 20742, USA
  4. School of Civil Engineering and Geosciences, Newcastle University, Drummond Building, Newcastle upon Tyne NE1 7RU, UK
  5. Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, USA

Correspondence to: Brian Kendall1 e-mail: brian.kendall@asu.edu



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