EGU21-460
https://doi.org/10.5194/egusphere-egu21-460
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Authigenic nanoscale magnetite within methanic marine sediments

Zhiyong Lin1,2, Xiaoming Sun1, Andrew Roberts3, Harald Strauss2, Benjamin Brunner4, and Jörn Peckmann5
Zhiyong Lin et al.
  • 1School of Marine Sciences, Sun Yat-sen University, Guangzhou 510006, China (linzhiy9@mail.sysu.edu.cn)
  • 2Institut für Geologie und Paläontologie, Westfälische Wilhelms-Universität Münster, Münster, D-48149, Germany
  • 3Research School of Earth Sciences, Australian National University, Canberra, ACT 2601, Australia
  • 4Department of Geological Sciences, The University of Texas, El Paso, TX 79902, USA
  • 5Institut für Geologie, Zentrum für Erdsystemforschung und Nachhaltigkeit, Universität Hamburg, Hamburg, D-20146, Germany.

Magnetic studies of methanic sediments focus mainly on magnetic iron sulfide (greigite, 3C pyrrhotite) formation and magnetic iron oxide (magnetite, titanomagnetite) dissolution, which mainly result from the release of hydrogen sulfide during sulfate-driven anaerobic oxidation of methane. In some instances, authigenic fine-grained magnetite within methanic environments is recognized from magnetic parameters, but the mechanisms for explaining its occurrence remain unclear. We report a novel authigenic nanoscale magnetite source in methanic marine sediments. The magnetite occurs in large concentrations in multiple horizons in a 230-m long sediment core with gas hydrate-bearing intervals. In contrast to typical biogenic magnetite produced by magnetotactic bacteria and dissimilatory iron-reducing bacteria, most particles have sizes of 200-800 nm and many are aligned in distinctive structures that resemble microbial precipitates. This new type of magnetite is interpreted to be a by-product of microbial iron reduction within methanic sediments. It will record younger paleomagnetic signals than surrounding sediments, which is important for paleomagnetic interpretations in methanic sediments.

How to cite: Lin, Z., Sun, X., Roberts, A., Strauss, H., Brunner, B., and Peckmann, J.: Authigenic nanoscale magnetite within methanic marine sediments, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-460, https://doi.org/10.5194/egusphere-egu21-460, 2021.

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