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Methodological add-ons to a non-destructive, micro-CT-based taxonomic/morphometric analysis of characean remains

Benyó-Korcsmáros Réka, Gulyás Sándor, Sebők Dániel, Benyó Dániel, Cseh Péter, Sümegi Pál

Geologos

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2023

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Vol. 29, No. 2

69--75

EN

Ever since its introduction, computed tomography has come a long way. No longer is it merely a method that is used in clinical diagnostics, but it is becoming more and more popular among palaeontologists because it can be used to analyse both external and internal structures of fossil remains, such as small insects, snail shells and plant remains. The present study describes non-destructive analyses of Late Cretaceous and early Holocene charophyte gyrogonites by using the micro-CT technique, from sample preparation (embedding, fixing) to visualisation and assessment of images obtained. In addition to this non-destructive examination, we wished to test whether or not computed tomography could be used to examine the gyrogonites. Our preliminary results have made it clear that the micro-CT technique is worth employing for further research. It has proved possible to visualise the samples in 3D, rotate them, and observe them from different directions. By using the appropriate parameters, we have also been able to observe density differences between parts of characean remains and to study several important defining features of these.

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Middle and Late Pleistocene loess-palaeosol archives in East Croatia: multi-proxy palaeoecological studies on Zmajevac and Šarengrad II sequences

Molnár Dávid, Makó László, Cseh Péter, Sümegi Pál, Fekete István, Galović Lidija

Studia Quaternaria

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2021

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Vol. 38, Nr 1

3--17

EN

Multi-proxy palaeoenvironmental analyses on the two loess-palaeosol sequences of Šarengrad II and Zmajevac (Croatia) provided the opportunity to obtain various data on climatic and environmental events that occurred in the southern part of the Carpathian Basin during the past 350,000 years. Palaeoecological horizons were reconstructed using sedimentological data (organic matter and carbonate content, grain-size distribution and magnetic susceptibility) and the dominance-based malacological results (MZs) supported by habitat and richness charts, moreover multi-variate statistics (cluster analysis). The correlation of the reconstructed palaeoecological horizons with global climatic trends (Marine Isotope Stages) determined the main accumulation processes in the examined areas. The palaeoecological analyses revealed specific accumulation conditions at both sequences, fluvial and aeolian environments at Šarengrad and a possible forest refuge at Zmajevac.

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MAR comparisons between different chronometric methods for two profilesin the Bodrogkeresztúr area

Makó László, Molnár Dávid, Cseh Péter, Sümegi Pál

Studia Quaternaria

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2021

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Vol. 38, Nr 1

67--73

EN

The deepening and exploration of the loess-palaeosol section at the foot of the Kopasz Hill at Bodrogkeresztúr have been carried out to expand the existing knowledge of the Carpathian foothill palaeoenvironmental factors and their impact. The study deals with particle size analysis, organic matter and carbonate content. For the presentation of age-depth models, the OSL dates of Bodrogkeresztúr (BKT) and the 14C dates of Bodrogkeresztúr, brickyard 1 were used-, and the diagrams of the Accumulation Rates (AR) derived from them. These were compared with Mass Accumulation Rate (MAR) calculations based on OSL and 14C data from BKT and 14C data from Bodrogkeresztúr, brickyard 1. It became evident that there is a significant difference between the two sections, which may be due to the upland position, the overlap, or the wind tunnel effect. Sedimentological studies revealed coarser grain composition, however, the nearly complete absence of coarser sand fraction is also noticeable in the case of BKT. Also, the entire section is characterized by increased carbonate content due to post-sedimentation processes, recarbonization and leaching. The AR and MAR results show the difference between the suitability of different chronometric methods, indicating that the top of both sections may have been redeposited or eroded.