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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
Aerobic bacterial pyrite oxidation and acid rock drainage during the Great Oxidation Event
Nature, Volume 478, No. 7369, Year 2011
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Description
The enrichment of redox-sensitive trace metals in ancient marine sedimentary rocks has been used to determine the timing of the oxidation of the Earth's land surface. Chromium (Cr) is among the emerging proxies for tracking the effects of atmospheric oxygenation on continental weathering; this is because its supply to the oceans is dominated by terrestrial processes that can be recorded in the Cr isotope composition of Precambrian iron formations. However, the factors controlling past and present seawater Cr isotope composition are poorly understood. Here we provide an independent and complementary record of marine Cr supply, in the form of Cr concentrations and authigenic enrichment in iron-rich sedimentary rocks. Our data suggest that Cr was largely immobile on land until around 2.48-Gyr ago, but within the 160-Myr that followed-and synchronous with independent evidence for oxygenation associated with the Great Oxidation Event (see, for example, refs 4-6)-marked excursions in Cr content and Cr/Ti ratios indicate that Cr was solubilized at a scale unrivalled in history. As Cr isotope fractionations at that time were muted, Cr must have been mobilized predominantly in reduced, Cr(iii), form. We demonstrate that only the oxidation of an abundant and previously stable crustal pyrite reservoir by aerobic-respiring, chemolithoautotrophic bacteria could have generated the degree of acidity required to solubilize Cr(iii) from ultramafic source rocks and residual soils. This profound shift in weathering regimes beginning at 2.48-Gyr ago constitutes the earliest known geochemical evidence for acidophilic aerobes and the resulting acid rock drainage, and accounts for independent evidence of an increased supply of dissolved sulphate and sulphide-hosted trace elements to the oceans around that time. Our model adds to amassing evidence that the Archaean-Palaeoproterozoic boundary was marked by a substantial shift in terrestrial geochemistry and biology. © 2011 Macmillan Publishers Limited. All rights reserved.
Authors & Co-Authors
Konhauser, Kurt O.
Canada, Edmonton
University of Alberta
Lalonde, Stefan V.
Canada, Edmonton
University of Alberta
France, Plouzane
Institut Universitaire Européen de la Mer Iuem
Planavsky, Noah J.
United States, Riverside
University of California, Riverside
Pecoits, Ernesto
Canada, Edmonton
University of Alberta
Lyons, Timothy W.
United States, Riverside
University of California, Riverside
Rouxel, Olivier J.
France, Plouzane
Institut Universitaire Européen de la Mer Iuem
France, Plouzane
Ifremer Institut Francais de Recherche Pour L'exploitation de la Mer
Barley, Mark E.
Australia, Perth
The University of Western Australia
Rosière, Carlos Alberto
Brazil, Belo Horizonte
Universidade Federal de Minas Gerais
Fralick, Philip W.
Canada, Thunder Bay
Lakehead University
Kump, Lee R.
United States, University Park
Pennsylvania State University
Bekker, Andrey Yu
Canada, Winnipeg
University of Manitoba
Statistics
Citations: 265
Authors: 11
Affiliations: 10
Identifiers
Doi:
10.1038/nature10511
ISSN:
14764687