No abstract

Abandoned channels are essential in the Quaternary floodplains, and their infill contains different paleoenvironment recorders. Grain-size distribution (GSD) is one proxy that helps characterize the alluviation and associated sedimentological processes of the abandoned channels. The classic statistical methods of the grain-size analysis provide insufficient information on the whole distribution; this necessitates a more comprehensive approach. Grain-size endmember modeling (EMM) is one approach beyond the traditional procedures that helps unmix the GSDs. This study describes the changes in the depositional process by unmixing the GSDs of a Holocene abandoned channel through parameterized EMM integrated with lithofacies, age–depth model, loss-on-ignition (LOI), and magnetic susceptibility (MS). This approach effectively enabled the quantification and characterization of up to four endmembers (EM1-4); the characteristics of grain-size endmembers imply changes in sedimentary environments since 8000 BP. EM1 is mainly clay and very fine silt, representing the fine component of the distribution corresponding to the background of quiet water sedimentation of the lacustrine phase. EM2 and EM3 are the intermediate components representing the distal overbank deposits of the flood. EM4 is dominated by coarse silt and very fine sand, representing deposition of overbank flow during the flood periods. This paper demonstrates that the parametrized grain-size EMM is reasonable in characterizing abandoned channel infill sedimentary depositional and sedimentation history.

The 10 m thick Madaras loess-palaeosol profile is one of the Hungarian outcrops that yielded Upper Palaeolithic artefacts in 1966. To clarify the nature of the deposits and establish a reliable litho-and chronostratigraphy, a profile was opened and sampled at 25 cm intervals on the northern side of the brickyard in 1975. Analyses focused on grain size, carbonate content and the mollusc fauna. The chronology was based on the mollusc composition and a single date from the archaeological layer at the depth of ca 7 m below the surface. The 1975 profile was destroyed by mining but the reposited samples allowed an extended analysis of this important Marine Isotope Stage 2 record to which archaeological features were directly assigned. A new absolute chronology was built based on 11 14 C dates. Environmental magnetic, geochemical and palaeoecological investigations allowed a refined view of site evolution with reliable chronology for the Last Glacial Maximum. Our results corroborated those of previous investigations done on other coeval loess-palaeosol sequences of the Southern Carpathian Basin. This also allowed for a temporal correlation to another local record with the published high-resolution chronology of the same brickyard and enabled modelling of local-scale heterogeneity of the environment in the long run.

The loess-paleosol profile near the settlement of Pécel has a notable size among the loess-paleosol sequences of the Northern Carpathian territories. Therefore, comprehensive sedimentological examinations were performed to understand the profile and the information preserved in it. The past periodicity and intensity of winds were showed by particle composition studies (GSI, U-ratio). At least two source areas can be presumed based on geochemical indices (CIA, CIW, Rb/Sr, Zr/Rb). Based on the characteristics of the chemical composition of sulphide minerals (P, S, Pb, Ni, As sulphides), the lower 10 m of the profile was supposed to be transported from the NW direction (Buda Thermal Karst, Börzsöny, Cserhát). Sufficient information is not yet available in order to determine the source area of the upper 10 m. By using the mentioned indexes, major developing and weathering horizons also could be identified.

The two loess-paleosol sequences of Vill anyk€ ovesd and M aza preserved specific paleoecological information of the Late Pleistocene environmental conditions in SW-Hungary. For malacological examinations, sampling of 12 cm intervals were used; homogenous amounts of sediment (ca. 5 kg) were collected. During the malacological examinations, more than 27,000 specimens were identified. Interpreting their environmental and climatic demands the paleoclimate and paleoenvironment of the last 80,000 years could be reconstructed. The results of the malacological investigations of Vill anyk€ ovesd sequence indicated 5 malacological zones (MZs) by the snail species' dominant occurrence. All of the 5 MZs indicate mild climatic conditions with only one cooling phase. The mild climatic conditions were reconstructed by the high dominance of thermophilous species, especially Pupilla triplicata. This warmth loving, xerophilous and open vegetation preferring species is present in the entire sequence, which indicates a refuge area of P. triplicata around Vill anyk€ ovesd. At the M aza sequence, 9 MZs could be allocated with mainly dominance of cold resistant species, indicating cooler climatic conditions than at Vill anyk€ ovesd. The reason of the high ratio of cold resistant species and the high number of MZs could be the geographic exposition of the M aza sequence. The M aza sequence is located in a bench between higher and lower reliefs on the northern pediment area of Mecsek Mountains. This indicates the presence of a fluctuation zone for the snail species in the area of M aza sequence. The Late Pleistocene sequences possess different climatic and environmental conditions during same timeframe, therefore we highlight that the previously reconstructed mosaic-like environmental patters in the Carpathian Basin are real properties in the region.