Publication Date:
2017-04-04
Description:
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
d13C values are depleted in 13C (d13C 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.
2007 Elsevier Ltd. All rights reserved.
Description:
Published
Description:
5155-5167
Description:
3.8. Geofisica per l'ambiente
Description:
JCR Journal
Description:
reserved
Keywords:
sulfide nodules
;
Valle Ricca section
;
04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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