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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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Applying grain-size and compositional data analysis for interpretation of the Quaternary oxbow lake sedimentation processes: eastern Great Hungarian Plain

Eltijani Abdelrhim, Molnár Dávid, Makó László, Geiger János, Sümegi Pál

Studia Quaternaria

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2022

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Vol. 39, Nr 2

83--93

EN

Grain size distribution is one of the paleoenvironmental proxies that provide insight statistical distribution of size fractions within the sediments. Multivariate statistics have been used to investigate the depositional process from the grain size distribution. Still, the direct application of the standard multivariate methods is not straightforward and can yield misleading interpretations due to the compositional nature of the raw grain size data. This paper is a methodological framework for grain size data characterization through the centered log ratio transformation and euclidean data, coupled with principal component analysis, cluster analysis, and linear discriminant analysis to examine Quaternary sediments from Tovises bed in the southeast Great Hungarian Plain. These approaches provide statistically significant and sedimentologically interpretable results for both datasets. However, the details by which they supplemented the conceptual model were significantly different, and this discrepancy resulted in a different temporal model of the depositional history.

3

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.

4

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.

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Holocene environmental history of the Bottomless Lake (Tăul fără fund) sphagnum peat bog in Bǎgǎu, Romania

Vári Tamás Zsolt, Molnár Dávid, Sümegi Pál, Sümegi Balázs Pál, Törőcsik Tünde, Szakál Edit, Benyó-Korcsmáros Réka

Studia Quaternaria

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2020

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Vol. 37, Nr 2

69--77

EN

This work focuses on the paleoenvironmental and palaeoclimatological history of the undisturbed core sequence of 8.6 m extracted from the Bottomless Lake (Tăul fără fund) sphagnum peat bog located in Bǎgǎu, Romania, which covers the last 8,600 years based on radiocarbon dating. By comparing results of archaeological and palaeoenvironmental investigations carried out so far in the area, results of the loss on ignition analyses and the data of the chronological analyses, it was possible to reconstruct climatic factors and anthropogenic impacts on the local environment. The undisturbed core sequence has above 86% organic matter content all along excluding the erosion horizons. Anthropogenic effects (building, woodcutting, pasturage, husbandry, farming) and changes in the local climate, vegetation, and environment increased the rate of the erosion and decreased the rate of the accumulation.

6

Revisiting the Palaeolithic site at Szeged-Öthalom: attempt for appoint the Palaeolithic horizon

Molnár Dávid, Makó László, Sümegi Pál, Sümegi Balázs P., Törőcsik Tünde

Studia Quaternaria

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2019

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Vol. 36, Nr 1

45--53

EN

This paper presents a new approach to study the palaeoecological and archaeological benefits of the previously investigated Szeged-Öthalom area. The aim was to combine the archaeological results with the palaeoecological ones by a new integral view. Age-depth models of 14C dated charcoal were calculated via Bayesian method to reconstruct the sediment accumulation rates in the investigated loess- palaeosol sequences. Moreover, the age of a Mammoth bone found in 1935 at the nearby Palaeolithic site was correlated with the calculated accumulation rates. Through our new results, the age of the Palaeolithic site could be correlated to the late LGM dust-accumulation-peak period. Even if this period is considered as cold and dry, the palaeoecological settings indicated dense forest cover and cool climate in the investigated area. This means that the palaeoenvironment may have encouraged the diffusion of Gravettian hunters in this area, founding campsites like Öthalom in the southern part of the Carpathian Basin.

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Environmental history of the Csorna Plain (Western Danube Plain, NW Hungary) from the Late Glacial to the Late Holocene as seen from data of multiproxy geoarchaeological investigations

Törőcsik Tünde, Gulyás Sándor, Sümegi Pál, Sümegi Balázs, Molnár Dávid, Benyó-Korcsmáros Réka

Studia Quaternaria

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2019

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Vol. 36, Nr 1

19--43

EN

This study presents the results of a comprehensive geoarchaeological study implemented at an archeological site covering ca. 5 ha near the city of Csorna on the NW part of the Danube Plain, NW Hungary. The site itself exposed a complex fluvial system of an ice age creek with near bank and overbank areas (levee, point bar, back swamp). Spatial distribution of archeological features allowed for the interpretation of differential use of the fluvial landscape by different cultures. According to our data, the referred fluvial system must have emerged during the Late Glacial. At this time, creeks originating from hills to the SE followed a uniform NW trajectory. From the Holocene, small creeks were beheaded turning into inactive flood channels. It was the time when the gradual infilling of the floodplain started. Alternating layers of floodwater coarses and floodplain fines mark recurring floods at our site. These could have been correlated with cooler, wetter climatic phases of the North Atlantic, Western Europe and high stands in Central European lakes. Highest floods are recorded during the Late Bronze and Iron Ages besides the Neolithic. Pollen data enabled us to make inferences on the vegetation as well.