Aerobic bacterial pyrite oxidation and acid rock drainage during the Great Oxidation Event

Autor: Andrey Bekker, Carlos Alberto Rosière, Timothy W. Lyons, Olivier Rouxel, Noah J. Planavsky, Lee R. Kump, Kurt O. Konhauser, Ernesto Pecoits, Mark Barley, Stephen J. Mojzsis, Phillip W. Fralick, Stefan V. Lalonde
Přispěvatelé: Department of Earth and Atmospheric Sciences [Edmonton], University of Alberta, Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Department of Earth Sciences [Riverside], University of California [Riverside] (UCR), University of California-University of California, Department of Geological Sciences [Boulder], University of Colorado [Boulder], Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), School of Earth and Environment, The University of Western Australia (UWA), University of Federal Minas Gerais, Department of Geology [Thunder Bay], Lakehead University, Instituto de Geociencias, Pennsylvania State University (Penn State), Penn State System-Penn State System, Department of Geological Sciences [Winnipeg], University of Manitoba [Winnipeg]
Rok vydání: 2011
Předmět:
Zdroj: Nature
Nature, Nature Publishing Group, 2011, 478 (7369), pp.369-373. ⟨10.1038/nature10511⟩
ISSN: 1476-4687
0028-0836
1476-4679
DOI: 10.1038/nature10511
Popis: International audience; 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 surface1,2. 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 formations3. 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 soils7. 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 sulphate8 and sulphide-hosted trace elements to the oceans around that time1,9. Our model adds to amassing evidence that the Archaean-Palaeoproterozoic boundary was marked by a substantial shift in terrestrial geochemistry and biology.
Databáze: OpenAIRE
Externí odkaz: