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Formation of iron sulfide nodules during anaerobic oxidation of methane

Formation of iron sulfide nodules during anaerobic oxidation of methane
Formation of iron sulfide nodules during anaerobic oxidation of methane
The biomarker compositions of iron sulfide nodules (ISNs; upper Pliocene Valle Ricca section near Rome, Italy) that contain the ferrimagnetic mineral greigite (Fe3S4) were examined. In addition to the presence of specific terrestrial and marine biomarkers, consistent with formation in coastal marine sediments, these ISNs contain compounds thought to originate from sulfate reducing bacteria (SRB). These compounds include a variety of low-molecular-weight and branched alkanols and several non-isoprenoidal dialkyl glycerol diethers (DGDs). In addition, archaeal biomarkers, including archaeol, macrocyclic isoprenoidal DGDs and isoprenoidal glycerol dialkyl glycerol tetraethers are also present. Both SRB and archaeal lipid ?13C values are depleted in 13C (?13C values are typically less than ?50‰), which suggests that the SRB and archaea consumed 13C depleted methane. These biomarker and isotopic signatures are similar to those found in cold seeps and marine sediments where anaerobic oxidation of methane (AOM) occurs with sulfate serving as the terminal electron acceptor. Association of AOM with formation of greigite-containing ISNs could provide an explanation for documented remagnetization of the Valle Ricca sediments. Upward migration of methane, subsequent AOM and associated authigenic greigite formation are widespread processes in the geological record that have considerable potential to compromise paleomagnetic records.

0016-7037
5155-5167
Dongen, Bart E.
c0cdb83e-d781-424e-a10d-f0654a45366e
Roberts, Andrew P.
4f062491-5408-4edb-8dd1-140c6a42e93f
Schouten, Stefan
0d0291ca-b8dc-48a2-b61c-798c650ec1fd
Jiang, Wei-Teh
1a596525-11f8-437a-a796-bc37f4e680c3
Florindo, Fabio
5953170b-79f7-431e-9e08-824a47e0fbd5
Pancost, Richard D.
5914e19e-7777-4304-9fd8-86e2e9cfe8a1
Dongen, Bart E.
c0cdb83e-d781-424e-a10d-f0654a45366e
Roberts, Andrew P.
4f062491-5408-4edb-8dd1-140c6a42e93f
Schouten, Stefan
0d0291ca-b8dc-48a2-b61c-798c650ec1fd
Jiang, Wei-Teh
1a596525-11f8-437a-a796-bc37f4e680c3
Florindo, Fabio
5953170b-79f7-431e-9e08-824a47e0fbd5
Pancost, Richard D.
5914e19e-7777-4304-9fd8-86e2e9cfe8a1

Dongen, Bart E., Roberts, Andrew P., Schouten, Stefan, Jiang, Wei-Teh, Florindo, Fabio and Pancost, Richard D. (2007) Formation of iron sulfide nodules during anaerobic oxidation of methane. Geochimica et Cosmochimica Acta, 71 (21), 5155-5167. (doi:10.1016/j.gca.2007.08.019).

Record type: Article

Abstract

The biomarker compositions of iron sulfide nodules (ISNs; upper Pliocene Valle Ricca section near Rome, Italy) that contain the ferrimagnetic mineral greigite (Fe3S4) were examined. In addition to the presence of specific terrestrial and marine biomarkers, consistent with formation in coastal marine sediments, these ISNs contain compounds thought to originate from sulfate reducing bacteria (SRB). These compounds include a variety of low-molecular-weight and branched alkanols and several non-isoprenoidal dialkyl glycerol diethers (DGDs). In addition, archaeal biomarkers, including archaeol, macrocyclic isoprenoidal DGDs and isoprenoidal glycerol dialkyl glycerol tetraethers are also present. Both SRB and archaeal lipid ?13C values are depleted in 13C (?13C values are typically less than ?50‰), which suggests that the SRB and archaea consumed 13C depleted methane. These biomarker and isotopic signatures are similar to those found in cold seeps and marine sediments where anaerobic oxidation of methane (AOM) occurs with sulfate serving as the terminal electron acceptor. Association of AOM with formation of greigite-containing ISNs could provide an explanation for documented remagnetization of the Valle Ricca sediments. Upward migration of methane, subsequent AOM and associated authigenic greigite formation are widespread processes in the geological record that have considerable potential to compromise paleomagnetic records.

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Published date: 1 November 2007

Identifiers

Local EPrints ID: 54906
URI: http://eprints.soton.ac.uk/id/eprint/54906
ISSN: 0016-7037
PURE UUID: e2188152-e892-4536-8696-06af2d0030af

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Date deposited: 23 Jul 2008
Last modified: 15 Mar 2024 10:51

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Contributors

Author: Bart E. Dongen
Author: Andrew P. Roberts
Author: Stefan Schouten
Author: Wei-Teh Jiang
Author: Fabio Florindo
Author: Richard D. Pancost

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