Publication Date:
2021-03-29
Description:
The relation of two well-known ancient
carbonate deposits to hydrocarbon seepage was
confirmed by this study. Archaea are found to be associated
with the formation of Oxfordian seep carbonates
from Beauvoisin and with a Miocene limestone from
Marmorito ("tube-worm limestone"). Carbonates
formed due to a mediation by archaea exhibit
extremely positive or extremely negative 813Ccarbonate
values, respectively. Highly positive values (+ 15%0)
reflect the use of 13C-enriched CO2 produced by
methanogenesis. Low 813C values of the Marmorito
carbonates (-30%0) indicate the oxidation of seepagederived
hydrocarbons. Likewise, the 813C content of
specific tail-to-tail linked isoprenoids, biomarkers for
archaea, was found to be strikingly depleted in these
sampies (as low as -115%0). The isotopic signatures
corroborate that archaea were involved in the cycling
of seepage-derived organic carbon at the ancient localities.
Another Miocene limestone ("Marmorito li mestone")
shows a strong imprint of methanotrophic
bacteria as indicated by 813C va lues of carbonate as low
J. Peckmann (IEI) . J. Reitner
Institut und Museum für Geologie und Paläontologie,
Georg-August-Universität. Goldschmidtstrasse 3,
D-37077 Göttingen, Germany
e-mail: jpeckma@gwdg.de.
Fax: + 49-551-397918
V. Thiel, W. Michaelis
Institut für Biogeochemie und Meereschemie, Universität
Hamburg, Bundesstrasse 55, D-20146 Hamburg, Germany
P. Clari, L. Martire
Dipartimento di Scienze della Terra, via Accademia delle
Scienze 5, 1-10123 Torino, Italy
C. Gaillard
UFR des Sciences de la Terre, UMR 5565 Centre de
Paleontologie stratigraphique et Paleoecologie, Universite
Claude Bemard, Lyon 1, 27-43 Boulevard du 11 Novembre,
F-69622 Villeurbanne Cedex, France
as -40%0 and biomarker evidence. Epifluorescence
microscopy and field-emission scanning electron
microscopy revealed that bacterial biofilms were
involved in carbonate aggregation. In addition to
lucinid bivalves previously reported from both localities,
we infer that sponges from Beauvoisin and tube
worms from Marmorito depended on chemosynthesis
as weil. Low 813C values of nodules related to sponge
taphonomy (-27%0) indicate that sponges might have
been Iinked to an enhanced hydrocarbon oxidation.
Tube worm fossils from Marmorito closely resemble
chemosynthetic pogonophoran tube worms from
Recent cold seeps and are embedded in isotopically
light carbonate (813C -300/00).
Keywords:
Paläontologie: Allgemeines
;
551
;
VU 000
;
38.20
;
38.2
Language:
English
Type:
article
,
publishedVersion
Format:
application/pdf
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