Carbon isotope excursions and microfacies changes in marine Permian-Triassic boundary sections in Hungary

Détails

ID Serval
serval:BIB_3450B1335FB3
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Carbon isotope excursions and microfacies changes in marine Permian-Triassic boundary sections in Hungary
Périodique
Palaeogeography, Palaeoclimatology, Palaeoecology
Auteur(s)
Haas J., Demény A., Hips K., Vennemann T.W.
ISSN-L
0031-0182
Statut éditorial
Publié
Date de publication
2006
Peer-reviewed
Oui
Volume
237
Pages
160-181
Langue
anglais
Résumé
Several Permian-Triassic boundary sections occur in various structural
units within Hungary. These sections represent different facies zones of
the western Palaeotethys margin. The Gardony core in the NE part of the
Transdanubian Range typically represents the inner ramp, while the
Balvany section in the Bukk Mountains of northern Hungary represents an
outer ramp setting. The two sections have different patterns for their
delta(13)C values. The Balvany section shows a continuous change towards
more negative delta(13)C values starting at the first biotic decline,
followed by a sharp, quasi-symmetric negative peak at the second
decline. The appearance of the delta(13)C peak has no relationship to
the lithology and occurs within a shale with low overall carbonate
content, indicating that the peak is not related to diagenesis or other
secondary influences. Instead, the shift and the peak reflect primary
processes related to changes in environmental conditions. The continuous
shift in delta(13)C values is most probably related to a decrease in
bioproductivity, whereas the sharp peak can be attributed to an addition
of C strongly depleted in (13)C to the ocean-atmosphere system. The most
plausible model is a massive release of methane-hydrate. The
quasi-symmetric pattern suggests a rapid warming-cooling cycle or
physical unroofing of sediments through slope-failure and releasing
methane-hydrate. The Gidony-1 core shows a continuous negative
delta(13)C shift starting below the P-T boundary. However, the detailed
analyses revealed a sharp delta(13)C peak in the boundary interval, just
below the major biotic decline, although its magnitude doesn't reach
that observed in the Balvany section. Based on careful textural
examination and high-resolution stable isotope microanalyses we suggest
that the suppression of the delta(13)C peak that is common in the
oolitic boundary sections is due to combined effects of condensed
sedimentation, sediment reworking and erosion, as well as perhaps
diagenesis. (c) 2005 Elsevier B.V All rights reserved.
Création de la notice
29/09/2012 16:23
Dernière modification de la notice
20/08/2019 13:20
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