Two-billion-year-old evaporites capture Earth’s great oxidation

Blättler, C. L. and Claire, M. W. and Prave, A. R. and Kirsimäe, K. and Higgins, J.A. and Medvedev, P. V. and Romashkin, A. E. and Rychanchik, D. V. and Zerkle, A. L. and Paiste, K. and Kreitsmann, T. and Millar, I. L. and Hayles, J. A. and Bao, H. and Turchyn, A. V. and Warke, M. R. and Lepland, A. (2018) Two-billion-year-old evaporites capture Earth’s great oxidation. Science. eaar2687. ISSN 0036-8075 DOI https://doi.org/10.1126/science.aar2687

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Abstract

Major changes in atmospheric and ocean chemistry occurred in the Paleoproterozoic Era (2.5–1.6 billion years ago). Increasing oxidation dramatically changed Earth’s surface, but few quantitative constraints exist on this important transition. This study describes the sedimentology, mineralogy, and geochemistry of a two-billion-year-old and ~800 m-thick evaporite succession from the Onega Basin in Russian Karelia. The deposit consists of a basal unit dominated by halite (~100 m) followed by anhydrite-magnesite (~500 m) and dolomite-magnesite (~200 m) dominated units. The evaporite minerals provide a robust constraint that marine sulfate concentrations were at least 10 mmol/kg, representing an oxidant reservoir equivalent to over 20% of the modern ocean-atmosphere oxidizing capacity. These results show that substantial amounts of surface oxidant accumulated during this critical transition in Earth’s oxygenation.

Item Type: Article
Uncontrolled Keywords: 2018AREP; IA74
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Science
Page Range: eaar2687
Identification Number: https://doi.org/10.1126/science.aar2687
Depositing User: Sarah Humbert
Date Deposited: 13 Apr 2018 10:26
Last Modified: 13 Apr 2018 10:26
URI: http://eprints.esc.cam.ac.uk/id/eprint/4253

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