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Sources and mechanisms for the enrichment of highly reactive iron in euxinic Black Sea sediments

Anderson, T.F. and Raiswell, R. (2004) Sources and mechanisms for the enrichment of highly reactive iron in euxinic Black Sea sediments. American Journal of Science, 304 (3). pp. 203-233. ISSN 0002-9599

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The deep basinal euxinic sediments of the Black Sea are enriched in iron that is highly susceptible to sulfidization compared to oxic/suboxic continental margin sediments in the Black Sea and oxic/dysoxic continental margin and deep-sea sediments worldwide. A mass balance treatment of iron speciation data from three deep basin sediment cores shows that this enrichment is due to a combination of (1)highly reactive iron-bearing phases (sulfides and oxides) whose ultimate source was by diagenetic mobilization from the shelf (Wijsman and others, 2001) and (2) enhanced iron reactivity in the lithogenous component of deep basinal sediments. The cause of the enhanced reactivity of lithogenous iron is problematical. Possible mechanisms include microbial oxidation of non-reactive iron silicates and the preferential deposition of a fine-grained, reactive iron-enriched lithogenous component in the deep basin by the fractionation of the lithogenous flux during transport across the shelf. The application of paleoredox indicators based on iron reactivity (Degree of Pyritization, Indicator of Anoxicity) should take into account that the availability of highly reactive iron, and hence the concentration of reactive iron phases in the sediment, is controlled by a variety of chemical, physical and biological factors, some of which are not related directly to redox conditions in the water column.

Item Type: Article
Institution: The University of Leeds
Academic Units: The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds)
Depositing User: Sherpa Assistant
Date Deposited: 11 Mar 2005
Last Modified: 08 Jun 2014 03:21
Published Version: http://www.geology.yale.edu/journals/Ajs.html/
Status: Published
Refereed: Yes
URI: http://eprints.whiterose.ac.uk/id/eprint/333

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