Lösz-paleotalaj sorozatokban megőrződött fitolitkészletek környezettörténeti és környezet régészeti vonatkozású kutatási lehetőségei = Environmental History and Environmental Archaeological Research Opportunities of Phytoliths Preserved in Loesspaleosoil Series

A fitolitok növények által termelt opálszemcsék, amelyek bizonyos tulajdonságaiknak köszönhetően (pl. nagy mennyiségben termelődnek, diagnosztikai értékkel bíró morfotípusok létezése, viszonylag nagy ellenállóképesség) az egykori (lokális) vegetáció indikátorai. Talajokból, üledékekből, üledékes kőzetekből kinyert fitolitkészlet értékes proxy adatot jelenthet a környezetrekonstrukciós vizsgálatokhoz. Régészeti kontextusból gyűjtött fitolitok az ember táj- és növényhasznosításának rekonstrukciójában játszhatnak fontos szerepet. A fitolitkészlet megfelelő kiértékeléséhez elengedhetetlen a fitolitkészletet ért tafonómiai folyamatok ismerete, hatásuk becslése. Lösz-paleotalaj sorozatok jelentős kiterjedésben és vastagságban borítják a szárazföldek felszínét. A lösz-paleotalaj sorozatokból kinyert fitolitkészleteket ennélfogva nagy kiterjedésű területen, jelentős időtávot (elsősorban a negyedidőszakot) átfogva lehet felhasználni a környezetrekonstrukciós vizsgálatok során. A fitolitkészlet környezetrekonstrukciós vizsgálatokban történő megfelelő kiértékeléséhez szükséges ismerni a lösz-paleotalaj sorozatok esetében érvényesülő főbb tafonómiai folyamatokat. A fitolitok lösz-paleotalaj sorozatokban történő megőrződését befolyásoló folyamatok jobb megismerése megbízhatóbb környezetrekonstrukciót tesz lehetővé

Tectonic and climatic control on terrace formation: Coupling in situ produced 10Be depth profiles and luminescence approach, Danube River, Hungary, Central Europe

International audience\textcopyright 2015 Elsevier Ltd.The terrace sequence of the Hungarian part of the Danube valley preserves a record of varying tectonic uplift rates along the river course and throughout several climate stages. To establish the chronology of formation of these terraces, two different dating methods were used on alluvial terraces: exposure age dating using in situ produced cosmogenic 10Be and luminescence dating. Using Monte Carlo approach to model the denudation rate-corrected exposure ages, in situ produced cosmogenic 10Be samples originated from vertical depth profiles enabled the determination of both the exposure time and the denudation rate. Post-IR IRSL measurements were carried out on K-feldspar samples to obtain the ages of sedimentation.The highest terrace horizon remnants of the study area provided a best estimate erosion-corrected minimum 10Be exposure age of \textgreater700 ka. We propose that the abandonment of the highest terrace of the Hungarian Danube valley was triggered by the combined effect of the beginning tectonic uplift and the onset of major continental glaciations of Quaternary age (around MIS 22). For the lower terraces it was possible to reveal close correlation with MIS stages using IRSL ages. The new chronology enabled the distinction of tIIb (~90 ka; MIS 5b-c) and tIIIa (~140 ka; MIS 6) in the study area. Surface denudation rates were well constrained by the cosmogenic 10Be depth profiles between 5.8 m/Ma and 10.0 m/Ma for all terraces. The calculated maximum incision rates of the Danube relevant for the above determined \textgreater700 ka time span were increasing from west (\textless0.06 mm/a) to east (\textless0.13 mm/a), toward the more elevated Transdanubian Range. Late Pleistocene incision rates derived from the age of the low terraces (~0.13-0.15 mm/a) may suggest a slight acceleration of uplift towards present

Clumped isotope paleotemperatures from MIS 5 soil carbonates in southern Hungary

Quantitative paleotemperature reconstructions for the continents, including East Central Europe, over marine isotope stage 5 (MIS 5) and specifically the last interglacial (LIG, MIS 5e) are scarce and mostly based on pollen assemblages. Here we provide soil and air temperature reconstructions for the summer season of MIS 5e (5c) using carbonate clumped isotope thermometry applied to soil carbonate concretions in the Dunaszekcső loess-paleosol record, Southern Hungary. The sediments making up the S1 pedocomplex investigated represent the MIS 5 as demonstrated by bracketing K-feldspar post-IR-IRSL225/290 ages of ~63 to 164 ka. Both the absolute ages and pedogenic susceptibility (χP) curve indicate that all the subtages of MIS 5 were found to be recorded in the sequence, and soil carbonates found >1 m depth below the paleosurface of the S1 soil provide pristine, undisturbed isotopic signals. The soil carbonate concretions likely formed during MIS 5e at a relatively shallow (20–50 cm) depth, but a later formation during MIS 5c at >50 cm depth is also plausible. Clumped isotope-based soil temperatures (ST-Δ47sc) ranged from 16 to 20 °C, and reconstructed summer season air temperatures (SATs) for the LIG are consistently lower than the modern values at the site by ~1–5 °C, matching surprisingly well the soil bacteria membrane lipid-based MIS 5e air temperature estimates from a nearby Serbian site. At the same time, the reconstructed SAT values do not match the 2–4 °C positive warm season anomalies modeled for East Central Europe between LIG and present-day in paleoclimate simulations. ST uncertainties of 1–6 °C, infiltration-driven cooling of soil temperatures, and the possibility of MIS 5c formation of the investigated carbonates may account for this proxy-model data discrepancy. Oxygen isotope compositions of summer season paleo-rainwaters for MIS 5e (5c), as reconstructed using the ST-Δ47sc and δ18Osc data of soil carbonates, were found in a range of −6.7 and −6.4‰, matching the modern mean summer season value of −6.2 ± 0.94‰ within error

Late Pleistocene paleosol formation in a dynamic aggradational microenvironment - A case study from the Malá nad Hronom loess succession (Slovakia)

The geomorphological characteristics of the loess succession at Malá nad Hronom (Slovakia) mean that it provides a valuable opportunity for the investigation of differences in soil formation in various topographic positions. Along with the semiquantitative characterization of the paleosols (on the basis of physical properties, texture, the characteristics of peds, clay films, horizon boundaries), high-resolution field magnetic susceptibility measurements and sampling were carried out along four different sections of the profile. Samples for luminescence dating were also taken, in order to establish the chronostratigraphical position of the paleosols studied. The comparison of various proxies revealed the differences in soil formation in a dynamic aggradational microenvironment for the same paleosol horizons located in various positions along the slope. Contrary to expectation, paleosols developed in local top or slope topographical positions did not display significant differences in e.g. in their degree of development, nor the characteristics of their magnetic susceptibility curves. In the case of paleosols in positions lower down the slope, signs of quasi-permanent sediment input could be recognized as being present as early as during the formation of the soil itself. This sediment input would seem to be surpassed in the case of pedogenesis strengthened by the climate of the last interglacial (marine isotope stage - MIS 5). Pedogenesis seems to be sustained by renewed intense dust accumulation in the Late Pleistocene, in MIS 3, though compared to MIS 5, the climate of MIS 3 did not favor intense pedogenesis. Despite the general belief that loess series formed in plateau positions can preserve terrestrial records without significant erosion, in the case of the Malá nad Hronom loess this is not so. Compared to the sequence affected by erosional events in the local top position, the sequence affected by quasi-continuous sediment input in the lower slope position seems to have preserved the soil horizons intact.International Visegrad Fund (project Number 11410020). The paper was also supported by a long-term conceptual development subvention available to research organizations RVO: 68145535 from the Institute of Geonics AS CR, by the Slovak Research and Development Agency under contract No. APVV-0625-11 (project “A new synthesis of the Western Carpathians landform evolution – preparation of the database for testing of key hypotheses”. B. Bradák acknowledges the financial support of project BU235P18 (Junta de Castilla y Leon, Spain) and the European Regional Development Fund (ERD), project PID2019-108753GB-C21 / AECI / 10.13039/501100011033 of the Agencia Estatal de Investigación and project PID2019-105796GB-100 / AECI / 10.13039/501100011033 of the Agencia Estatal de Investigación