Two-billion-year-old evaporites capture Earth's great oxidation.

Autor: Blättler CL; Department of Geosciences, Princeton University, Princeton, NJ 08544, USA. blattler@princeton.edu., Claire MW; School of Earth and Environmental Sciences, University of St Andrews, St Andrews KY16 9AL, Scotland, UK.; Centre for Exoplanet Science, University of St Andrews, St Andrews KY16 9AL, Scotland, UK.; Blue Marble Space Institute of Science, 1001 4th Avenue, Suite 3201, Seattle, WA 98154, USA., Prave AR; School of Earth and Environmental Sciences, University of St Andrews, St Andrews KY16 9AL, Scotland, UK., Kirsimäe K; Department of Geology, University of Tartu, 50411 Tartu, Estonia., Higgins JA; Department of Geosciences, Princeton University, Princeton, NJ 08544, USA., Medvedev PV; Institute of Geology, Karelian Research Centre, Pushkinskaya 11, 185610 Petrozavodsk, Russia., Romashkin AE; Institute of Geology, Karelian Research Centre, Pushkinskaya 11, 185610 Petrozavodsk, Russia., Rychanchik DV; Institute of Geology, Karelian Research Centre, Pushkinskaya 11, 185610 Petrozavodsk, Russia., Zerkle AL; School of Earth and Environmental Sciences, University of St Andrews, St Andrews KY16 9AL, Scotland, UK.; Centre for Exoplanet Science, University of St Andrews, St Andrews KY16 9AL, Scotland, UK., Paiste K; Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geosciences, UiT The Arctic University of Norway, 9037 Tromsø, Norway., Kreitsmann T; Department of Geology, University of Tartu, 50411 Tartu, Estonia., Millar IL; NERC (Natural Environment Research Council) Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Nottingham NG12 5GG, England, UK., Hayles JA; Department of Earth Science, Rice University, 6100 Main Street, Houston, TX 77005, USA., Bao H; Department of Geology and Geophysics, E235 Howe-Russell Geoscience Complex, Louisiana State University, Baton Rouge, LA 70803, USA., Turchyn AV; Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, England, UK., Warke MR; School of Earth and Environmental Sciences, University of St Andrews, St Andrews KY16 9AL, Scotland, UK., Lepland A; Geological Survey of Norway, 7491 Trondheim, Norway.; Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geosciences, UiT The Arctic University of Norway, 9037 Tromsø, Norway.; Department of Geology, University of Tartu, 50411 Tartu, Estonia.; Institute of Geology, Tallinn University of Technology, 19086 Tallinn, Estonia.
Jazyk: angličtina
Zdroj: Science (New York, N.Y.) [Science] 2018 Apr 20; Vol. 360 (6386), pp. 320-323. Date of Electronic Publication: 2018 Mar 22.
DOI: 10.1126/science.aar2687
Abstrakt: Major changes in atmospheric and ocean chemistry occurred in the Paleoproterozoic era (2.5 to 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 2-billion-year-old, ~800-meter-thick evaporite succession from the Onega Basin in Russian Karelia. The deposit consists of a basal unit dominated by halite (~100 meters) followed by units dominated by anhydrite-magnesite (~500 meters) and dolomite-magnesite (~200 meters). The evaporite minerals robustly constrain marine sulfate concentrations to at least 10 millimoles per kilogram of water, representing an oxidant reservoir equivalent to more than 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.
(Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)
Databáze: MEDLINE
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