Pervasive oxygenation along late Archaean ocean margins

Brian Kendall, Christopher T. Reinhard, Timothy W. Lyons, Alan J. Kaufman, Simon W. Poulton, Ariel Anbar

Research output: Contribution to journalArticlepeer-review

180 Scopus citations

Abstract

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 100 million years before the first significant increase in atmospheric O2 concentration.

Original languageEnglish (US)
Pages (from-to)647-652
Number of pages6
JournalNature Geoscience
Volume3
Issue number9
DOIs
StatePublished - Sep 1 2010

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

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