Miniaturized biosignature analysis reveals implications for the formation of cold seep carbonates at Hydrate Ridge (off Oregon, USA)
Zeitschrift: Biogeosciences, 20085, 3: 731 - 738
DOI: https://doi.org/10.5194/bg-5-731-2008
Persistent URL: http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/6664
Persistent URL: http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/6664
Leefmann, T.; Bauermeister, J.; Kronz, A.; Liebetrau, V.; Reitner, J.; Thiel, V., 2008: Miniaturized biosignature analysis reveals implications for the formation of cold seep carbonates at Hydrate Ridge (off Oregon, USA). In: Leefmann, T.; Bauermeister, J.; Kronz, A.; Liebetrau, V.; Reitner, J.; Thiel, V. (2008): Miniaturized biosignature analysis reveals implications for the formation of cold seep carbonates at Hydrate Ridge (off Oregon, USA), DOI: 10.5194/bg-5-731-2008.
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Methane-related carbonates from Hydrate Ridge
typically show several macroscopically distinguishable mineral
phases, namely whitish aragonite, lucent aragonite, and
gray micrite. The relationship of these phases to particular
microorganisms or biogeochemical processes is as yet
unclear. We used a miniaturized biomarker technique on
mg samples, combined with factor analysis and subsequent
electron microprobe analysis, to study lipid biomarkers and
chemical compositions of the individual phases. This allows
us to identify particular mechanisms involved in the
formation of the different carbonate precipitates. Our combined
analysis of biomarkers and petrographic traits shows
that most of the lipids related to the anaerobic oxidation of
methane (>90% by weight) are concentrated within only
a minor compartment ( 20% by volume) of the Hydrate
Ridge carbonates, the whitish aragonite. The patterns indicate
that the whitish aragonite represents fossilized biofilms
of methanotrophic consortia containing mainly archaea of
the ANME-2 group and sulfate reducing bacteria, whereas
the precipitation of the lucent aragonite may have lacked the
immediate proximity of microorganisms during formation.
By contrast, the gray micrite formed by incorporation of allochthonous
organic and inorganic matter during carbonate
precipitation induced by the anaerobic oxidation of methane
involving ANME-1 archaea.
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