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  • 1
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    Dynamic anoxic ferruginous conditions during the end-Permian mass extinction and recovery (2016)
    Springer Nature
    Details
    Publication Date: 2016-07-21
    Description: Article Oceanic anoxia is invoked for driving the Permo-Triassic Mass Extinction, but the timing, distribution and chemical state are poorly understood. Here, the authors show that fluctuations of anoxic, non-sulfidic (ferruginous) conditions were important for the delayed biotic recovery in the Neo-Tethys. Nature Communications doi: 10.1038/ncomms12236 Authors: M. O. Clarkson, R. A. Wood, S. W. Poulton, S. Richoz, R. J. Newton, S. A. Kasemann, F. Bowyer, L. Krystyn
    Electronic ISSN: 2041-1723
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 2
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    Influence of diagenesis on the stable isotopic composition of biogenic carbonates from the Gulf of Tehuantepec oxygen minimum zone (2012)
    Wiley
    Details
    Publication Date: 2012-04-11
    Description: In order to evaluate the influence of diagenetic and post-sampling processes on the stable oxygen and carbon isotope compositions of biogenic carbonates, we conducted a multiproxy study of organic-rich sediments from the eastern Pacific oxygen minimum zone. Core MD02-2520, which was retrieved from the Gulf of Tehuantepec (Mexico), has seasonal laminations and covers the last 40 kyr. Together with the presence of gypsum crystals and inorganic calcite aggregates, the occurrence of large excursions in the stable oxygen and carbon isotope records of both planktonic and benthic foraminifera (as large as +3‰ in δ18O and −5‰ in δ13C) point to significant secondary transformations. Storage-related gypsum precipitation was ruled out since it implies sulfide reoxidation by oxygen that triggers biogenic calcite dissolution, which proved to be of minor importance here. Instead, precipitation of authigenic calcite during early diagenesis appears to be the most likely process responsible for the observed isotopic excursions. The δ13C composition for inorganic calcite aggregates (−5 to −7‰) suggests a major contribution from anaerobic oxidation of organic matter. The δ34S composition for gypsum crystals (−10 to +15‰) suggests a major contribution from anaerobic reoxidation of authigenic sulfides, potentially involving reactions with metal oxides and sulfur disproportionation. A minor part of the gypsum might possibly have formed as a result of local pore water salinity increases induced by gas hydrate formation.
    Electronic ISSN: 1525-2027
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 3
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    Tracing the stepwise oxygenation of the Proterozoic ocean (2008)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2008-03-28
    Description: Biogeochemical signatures preserved in ancient sedimentary rocks provide clues to the nature and timing of the oxygenation of the Earth's atmosphere. Geochemical data suggest that oxygenation proceeded in two broad steps near the beginning and end of the Proterozoic eon (2,500 to 542 million years ago). The oxidation state of the Proterozoic ocean between these two steps and the timing of deep-ocean oxygenation have important implications for the evolutionary course of life on Earth but remain poorly known. Here we present a new perspective on ocean oxygenation based on the authigenic accumulation of the redox-sensitive transition element molybdenum in sulphidic black shales. Accumulation of authigenic molybdenum from sea water is already seen in shales by 2,650 Myr ago; however, the small magnitudes of these enrichments reflect weak or transient sources of dissolved molybdenum before about 2,200 Myr ago, consistent with minimal oxidative weathering of the continents. Enrichments indicative of persistent and vigorous oxidative weathering appear in shales deposited at roughly 2,150 Myr ago, more than 200 million years after the initial rise in atmospheric oxygen. Subsequent expansion of sulphidic conditions after about 1,800 Myr ago (refs 8, 9) maintained a mid-Proterozoic molybdenum reservoir below 20 per cent of the modern inventory, which in turn may have acted as a nutrient feedback limiting the spatiotemporal distribution of euxinic (sulphidic) bottom waters and perhaps the evolutionary and ecological expansion of eukaryotic organisms. By 551 Myr ago, molybdenum contents reflect a greatly expanded oceanic reservoir due to oxygenation of the deep ocean and corresponding decrease in sulphidic conditions in the sediments and water column.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Scott, C -- Lyons, T W -- Bekker, A -- Shen, Y -- Poulton, S W -- Chu, X -- Anbar, A D -- England -- Nature. 2008 Mar 27;452(7186):456-9. doi: 10.1038/nature06811.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth Sciences, University of California, Riverside, California 92521, USA. cscot002@ucr.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18368114" target="_blank"〉PubMed〈/a〉
    Keywords: Atmosphere/chemistry ; Geologic Sediments/chemistry ; History, Ancient ; Molybdenum/analysis ; Oceans and Seas ; Oxygen/*analysis/chemistry ; Seawater/*chemistry ; Sulfides/chemistry ; Time Factors
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 4
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    Fluctuations in Precambrian atmospheric oxygenation recorded by chromium isotopes (2009)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2009-09-11
    Description: Geochemical data suggest that oxygenation of the Earth's atmosphere occurred in two broad steps. The first rise in atmospheric oxygen is thought to have occurred between approximately 2.45 and 2.2 Gyr ago, leading to a significant increase in atmospheric oxygen concentrations and concomitant oxygenation of the shallow surface ocean. The second increase in atmospheric oxygen appears to have taken place in distinct stages during the late Neoproterozoic era ( approximately 800-542 Myr ago), ultimately leading to oxygenation of the deep ocean approximately 580 Myr ago, but details of the evolution of atmospheric oxygenation remain uncertain. Here we use chromium (Cr) stable isotopes from banded iron formations (BIFs) to track the presence of Cr(VI) in Precambrian oceans, providing a time-resolved picture of the oxygenation history of the Earth's atmosphere-hydrosphere system. The geochemical behaviour of Cr is highly sensitive to the redox state of the surface environment because oxidative weathering processes produce the oxidized hexavalent [Cr(VI)] form. Oxidation of reduced trivalent [Cr(III)] chromium on land is accompanied by an isotopic fractionation, leading to enrichment of the mobile hexavalent form in the heavier isotope. Our fractionated Cr isotope data indicate the accumulation of Cr(VI) in ocean surface waters approximately 2.8 to 2.6 Gyr ago and a likely transient elevation in atmospheric and surface ocean oxygenation before the first great rise of oxygen 2.45-2.2 Gyr ago (the Great Oxidation Event). In approximately 1.88-Gyr-old BIFs we find that Cr isotopes are not fractionated, indicating a decline in atmospheric oxygen. Our findings suggest that the Great Oxidation Event did not lead to a unidirectional stepwise increase in atmospheric oxygen. In the late Neoproterozoic, we observe strong positive fractionations in Cr isotopes (delta(53)Cr up to +4.9 per thousand), providing independent support for increased surface oxygenation at that time, which may have stimulated rapid evolution of macroscopic multicellular life.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Frei, Robert -- Gaucher, Claudio -- Poulton, Simon W -- Canfield, Don E -- England -- Nature. 2009 Sep 10;461(7261):250-3. doi: 10.1038/nature08266.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Geography and Geology and Nordic Center for Earth Evolution (NordCEE), University of Copenhagen, Oster Voldgade 10, 1350 Copenhagen, Denmark.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19741707" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atmosphere/*chemistry ; Biodiversity ; Chromium/*analysis/chemistry ; Chromium Isotopes ; History, Ancient ; Iron/analysis/metabolism ; Manganese Compounds/metabolism ; Oceans and Seas ; Oxidation-Reduction ; Oxides/metabolism ; Oxygen/analysis/*metabolism ; Seawater/chemistry
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 5
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    Late-Neoproterozoic deep-ocean oxygenation and the rise of animal life (2006)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2006-12-13
    Description: Because animals require oxygen, an increase in late-Neoproterozoic oxygen concentrations has been suggested as a stimulus for their evolution. The iron content of deep-sea sediments shows that the deep ocean was anoxic and ferruginous before and during the Gaskiers glaciation 580 million years ago and that it became oxic afterward. The first known members of the Ediacara biota arose shortly after the Gaskiers glaciation, suggesting a causal link between their evolution and this oxygenation event. A prolonged stable oxic environment may have permitted the emergence of bilateral motile animals some 25 million years later.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Canfield, Don E -- Poulton, Simon W -- Narbonne, Guy M -- New York, N.Y. -- Science. 2007 Jan 5;315(5808):92-5. Epub 2006 Dec 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Nordic Center for Earth Evolution (NordCEE) and Institute of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark. dec@biology.sdu.dk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17158290" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atmosphere ; *Biological Evolution ; *Fossils ; Geologic Sediments/chemistry ; Ice Cover ; Iron/analysis ; Newfoundland and Labrador ; Oxidation-Reduction ; Oxygen/*analysis ; Seawater/*chemistry ; Sulfates/analysis ; Time
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 6
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    Ferruginous conditions dominated later neoproterozoic deep-water chemistry (2008)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2008-07-19
    Description: Earth's surface chemical environment has evolved from an early anoxic condition to the oxic state we have today. Transitional between an earlier Proterozoic world with widespread deep-water anoxia and a Phanerozoic world with large oxygen-utilizing animals, the Neoproterozoic Era [1000 to 542 million years ago (Ma)] plays a key role in this history. The details of Neoproterozoic Earth surface oxygenation, however, remain unclear. We report that through much of the later Neoproterozoic (〈742 +/- 6 Ma), anoxia remained widespread beneath the mixed layer of the oceans; deeper water masses were sometimes sulfidic but were mainly Fe2+-enriched. These ferruginous conditions marked a return to ocean chemistry not seen for more than one billion years of Earth history.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Canfield, Donald E -- Poulton, Simon W -- Knoll, Andrew H -- Narbonne, Guy M -- Ross, Gerry -- Goldberg, Tatiana -- Strauss, Harald -- New York, N.Y. -- Science. 2008 Aug 15;321(5891):949-52. doi: 10.1126/science.1154499. Epub 2008 Jul 17.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Nordic Center for Earth Evolution and Institute of Biology, Campusvej 55, University of Southern Denmark, 5230 Odense, Denmark. dec@biology.sdu.dk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18635761" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atmosphere ; Geologic Sediments/*chemistry ; Ice Cover ; Iron/*analysis ; Oceans and Seas ; Oxidation-Reduction ; Oxygen/*analysis ; Seawater/*chemistry ; Sulfates/analysis ; Sulfides/analysis ; Time
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 7
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    Ocean acidification and the Permo-Triassic mass extinction (2015)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2015-04-11
    Description: Ocean acidification triggered by Siberian Trap volcanism was a possible kill mechanism for the Permo-Triassic Boundary mass extinction, but direct evidence for an acidification event is lacking. We present a high-resolution seawater pH record across this interval, using boron isotope data combined with a quantitative modeling approach. In the latest Permian, increased ocean alkalinity primed the Earth system with a low level of atmospheric CO2 and a high ocean buffering capacity. The first phase of extinction was coincident with a slow injection of carbon into the atmosphere, and ocean pH remained stable. During the second extinction pulse, however, a rapid and large injection of carbon caused an abrupt acidification event that drove the preferential loss of heavily calcified marine biota.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Clarkson, M O -- Kasemann, S A -- Wood, R A -- Lenton, T M -- Daines, S J -- Richoz, S -- Ohnemueller, F -- Meixner, A -- Poulton, S W -- Tipper, E T -- New York, N.Y. -- Science. 2015 Apr 10;348(6231):229-32. doi: 10.1126/science.aaa0193.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Geosciences, University of Edinburgh, West Mains Road, Edinburgh EH9 3FE, UK. matthew.clarkson@otago.ac.nz. ; Faculty of Geosciences and MARUM-Center for Marine Environmental Sciences, University of Bremen, 28334 Bremen, Germany. ; School of Geosciences, University of Edinburgh, West Mains Road, Edinburgh EH9 3FE, UK. ; College of Life and Environmental Sciences, University of Exeter, Laver Building, North Parks Road, Exeter EX4 4QE, UK. ; Institute of Earth Sciences, NAWI Graz, University of Graz, Heinrichstrasse 26, 8010 Graz, Austria. ; School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK. ; Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25859043" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Aquatic Organisms ; Atmosphere ; Boron ; *Carbon ; Carbon Cycle ; Carbon Isotopes ; Ecosystem ; *Extinction, Biological ; Hydrogen-Ion Concentration ; Isotopes ; Oceans and Seas ; Seawater/*chemistry ; Time
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 8
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    Stepwise Earth oxygenation is an inherent property of global biogeochemical cycling (2019)
    American Association for the Advancement of Science (AAAS)
    In: Science
    Details
    Publication Date: 2019
    Description: 〈p〉Oxygenation of Earth’s atmosphere and oceans occurred across three major steps during the Paleoproterozoic, Neoproterozoic, and Paleozoic eras, with each increase having profound consequences for the biosphere. Biological or tectonic revolutions have been proposed to explain each of these stepwise increases in oxygen, but the principal driver of each event remains unclear. Here we show, using a theoretical model, that the observed oxygenation steps are a simple consequence of internal feedbacks in the long-term biogeochemical cycles of carbon, oxygen, and phosphorus, and that there is no requirement for a specific stepwise external forcing to explain the course of Earth surface oxygenation. We conclude that Earth’s oxygenation events are entirely consistent with gradual oxygenation of the planetary surface after the evolution of oxygenic photosynthesis.〈/p〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 9
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    Pathways for Neoarchean pyrite formation constrained by mass-independent sulfur isotopes (2013)
    National Academy of Sciences
    Details
    Publication Date: 2013-02-13
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 10
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    A continental-weathering control on orbitally driven redox-nutrient cycling during Cretaceous Oceanic Anoxic Event 2 (2015)
    Geological Society of America (GSA)
    In: Geology
    Details
    Publication Date: 2015-10-20
    Description: The Cretaceous period (~145–65 m.y. ago) was characterized by intervals of enhanced organic carbon burial associated with increased primary production under greenhouse conditions. The global consequences of these perturbations, oceanic anoxic events (OAEs), lasted up to 1 m.y., but short-term nutrient and climatic controls on widespread anoxia are poorly understood. Here, we present a high-resolution reconstruction of oceanic redox and nutrient cycling as recorded in subtropical shelf sediments from Tarfaya, Morocco, spanning the initiation of OAE2. Iron-sulfur systematics and biomarker evidence demonstrate previously undescribed redox cyclicity on orbital time scales, from sulfidic to anoxic ferruginous (Fe-rich) water-column conditions. Bulk geochemical data and sulfur isotope modeling suggest that ferruginous conditions were not a consequence of nutrient or sulfate limitation, despite overall low sulfate concentrations in the proto–North Atlantic. Instead, fluctuations in the weathering influxes of sulfur and reactive iron, linked to a dynamic hydrological cycle, likely drove the redox cyclicity. Despite the potential for elevated phosphorus burial in association with Fe oxides under ferruginous conditions on the Tarfaya shelf, porewater sulfide generation drove extensive phosphorus recycling back to the water column, thus maintaining widespread open-ocean anoxia.
    Print ISSN: 0091-7613
    Electronic ISSN: 1943-2682
    Topics: Geosciences
    Published by Geological Society of America (GSA)
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