Paleotemperature and carbon cycle changes on geological time scales

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Contact person:

Dr. Demény Attila

The main research fields

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1. Stable isotope studies on major extinction events (Permian-Triassic and Triassic-Jurassic) have been conducted in joint projects financed by the Hungarian Research Fund (2001-2007).
   Co-operation partners: Dr. Janos Haas (Eötvös Loránd University & Hungarian Academy of Sciences, Geological, Geophysical & Space Science Research Group) and Dr. Jozsef Palfy (Hungarian Natural Science Museum & Hungarian Academy of Sciences, Paleontological Research Group)
2. Determination of Mesozoic paleotemperatures by means of stable isotope thermometry
   As the climate of the Mesozoic was comparable to the extreme predictions of present-day global warming, its research can help refine climate models by providing accurate paleotemperature signals. The major aims of the project are the analyses of internal structures of calcitic fossils from Hungarian, Slovenian, and selected European locations to detect diagenetic influences, and the determinations of accurate and reliable paleotemperature data by analyzing the collected aptychi, rhyncholites, belemnites, and brachiopods with the aim of clarifying Mesozoic climate conditions and the paleolatitudinal distribution of seawater temperature covering different time intervals.
3. The analysis of the formation and evolution of microfabric features in mandible organs of cephalopods
   The main goal of the present project is to perform microfabric analyses and their mathematical modeling on calcitic elements mandible organs of cephalopods (aptychus and rhyncholite) from Hungarian and European sites to determine the origin, function and evolution of the structures.

Financial support: NKFIH SNN 152120 Slovenian-Hungarian collaboration project

Publications

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• Demény, A., Bujtor, L., Domokos, G., A. Sipos, A., Farkas, Cs., Ferencz, E., Topa, B., Leskó, M., Zajzon, N. (2025) Calcitic coverings of the lower jaw of Jurassic ammonites exhibit Bouligand-like structures. Communications Earth & Environment 6 (1), 927. https://doi.org/10.1038/s43247-025-02892-z
• Bujtor, L., Demény, A., Németh, P., Bajnóczi, B. (2024): Laevaptychi as reliable paleotemperature archives: high-resolution stable isotope compositions of Kimmeridgian (Jurassic) lamellar structured aspidoceratid lower mandibles from Zengővárkony (Mecsek Mountains, Hungary). International Journal of Earth Sciences 113, 353 – 367. https://doi.org/10.1007/s00531-023-02376-5
• Haas, J., Demény, A., Hips, K., Zajzon, N., Weiszburg, T.G., Sudar, M., Pálfy, J. (2007): Biotic and environmental changes in the Permian-Triassic boundary interval recorded on a western Tethyan ramp in the Bükk Mountains, Hungary. Global and Planetary Change, 55, 136-154. https://doi.org/10.1016/j.gloplacha.2006.06.010
• Pálfy, J., Demény, A., Haas, J., Carter, E.S., Görög, Á., Halász, D., Oravecz-Scheffer, A., Hetényi, M., Márton, E., Orchard, M.J., Ozsvárt, P., Vetõ, I., Zajzon, N. (2007): Triassic-Jurassic boundary events inferred from integrated stratigraphy of the Csõvár section, Hungary. Palaeogeography, Palaeoclimatology, Palaeoecology, 244, 11-33. https://doi.org/10.1016/j.palaeo.2006.06.021
• Haas, J., Demény, A., Hips, K., Vennemann, T.W. (2006): Carbon isotope excursions and microfacies changes in marine Permian-Triassic boundary sections in Hungary. Palaeogeography, Palaeoclimatology, Palaeoecology, 237, 160-181. https://doi.org/10.1016/j.palaeo.2005.11.017
• Pálfy, J., Demény, A., Haas, J., Hetényi, M., Orchard, M., Vetõ, I. (2001): Carbon isotope anomaly and other geochemical changes at the Triassic-Jurassic boundary from a marine section in Hungary. Geology, 29, 1047-1050. https://doi.org/10.1130/0091-7613(2001)029<1047:CIAAOG>2.0.CO;2