New Data on the Expression of the Early Eocene Hyperthermals in Northern Bulgaria: Riben Section Revisited

Authors

  • Kristalina Stoykova Department of Paleontology, Stratigraphy and Sedimentology, Geological Institute Bulgarian Academy of Sciences
  • Elena Koleva-Rekalova Department of Paleontology, Stratigraphy and Sedimentology, Geological Institute Bulgarian Academy of Sciences
  • Torsten Vennemann Stable Isotope Laboratory, University of Lausanne, Switzerland
  • Marin Ivanov Faculty of Geology and Geography, Sofia University “St. Kliment Ohridski”, Bulgaria

DOI:

https://doi.org/10.7546/CRABS.2023.11.06

Keywords:

PETM, Early Eocene hyperthermals, calcareous nannofossils, carbonate content, δ13C and δ18O isotopes, northern Bulgaria

Abstract

We present new lithologic, nannofossil biostratigraphic and benthic carbon and oxygen isotope records for a marly-rich, 11 m thick Paleocene-Eocene section, now exposed at an old quarry at Riben Village, northern Bulgaria. The occurrence of NP9, NP10 and NP11 nannofossil zones is evidenced by detailed high-resolution nannofossil biostratigraphy. The carbon dissolution interval is marked by the abrupt drop of CaCO3 content and deposition of a clay interval at the onset of the Paleocene-Eocene Thermal Maximum (PETM). Stable isotope analyses of δ13C and δ18O were performed on benthic-foraminiferal tests. An unusual two-fold carbon isotope excursion (CIE) in the PETM interval is documented (total negative shift of 2.89‰). Moreover, three paired negative excursions: two in the Paleocene within the PETM interval, upper NP9 zone, and one within the early Eocene, NP11 zone are identified. The most prominent negative carbon isotope excursion (4.90‰ negative shift) is related with ETM3 (or “X” event), 52.84 Ma ago.

Integration of nannofossil biostratigraphy, benthic stable isotope data sets and lithology unravel two separate early Eocene hyperthermal events: the PETM (= ETM1) and the ETM3 (= “X” event), recorded at Riben section.

Author Biographies

Kristalina Stoykova, Department of Paleontology, Stratigraphy and Sedimentology, Geological Institute Bulgarian Academy of Sciences

Mailing Address:
Department of Paleontology, Stratigraphy and Sedimentology,
Geological Institute
Bulgarian Academy of Sciences
Akad. G. Bonchev St, B. 24
1113 Sofia, Bulgaria

E-mail: stoykova@geology.bas.bg

Elena Koleva-Rekalova, Department of Paleontology, Stratigraphy and Sedimentology, Geological Institute Bulgarian Academy of Sciences

Mailing Address:
Department of Paleontology, Stratigraphy and Sedimentology,
Geological Institute
Bulgarian Academy of Sciences
Akad. G. Bonchev St, B. 24
1113 Sofia, Bulgaria

E-mail: e_koleva@geology.bas.bg

Torsten Vennemann, Stable Isotope Laboratory, University of Lausanne, Switzerland

Mailing Address:
Stable Isotope Laboratory,
University of Lausanne
Geopolis 4634
CH-1015 Dorigny, Switzerland

E-mail: Torsten.Vennemann@unil.ch

Marin Ivanov, Faculty of Geology and Geography, Sofia University “St. Kliment Ohridski”, Bulgaria

Mailing Address:
Faculty of Geology and Geography,
Sofia University “St. Kliment Ohridski”
15 Tsar Osvoboditel Blvd
1504 Sofia, Bulgaria

E-mail: mivanov@gea.uni-sofia.bg

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Published

27-11-2023

How to Cite

[1]
K. Stoykova, E. Koleva-Rekalova, T. Vennemann, and M. Ivanov, “New Data on the Expression of the Early Eocene Hyperthermals in Northern Bulgaria: Riben Section Revisited”, C. R. Acad. Bulg. Sci. , vol. 76, no. 11, pp. 1687–1697, Nov. 2023.

Issue

Section

Geology