A multi-proxy study on polygenetic middle-to late pleistocene paleosols in the Hevizgyork loess-paleosol sequence (Hungary)

摘要

A multi-proxy analysis, including grain size, magnetic susceptibility and the examination of stable isotopes of hypocoatings, was performed on the loess-paleosol succession at Hevizgyork (Hungary). Field investigations suggested a continuous record of sedimentation and pedogenesis. However, after the identification of the Bag Tephra, it revealed that paleosols and loess units are missing from the section, despite no obvious signs of erosion. Fluctuations in the measured proxies indicate a polygenetic development of the upper paleosol.Paleogeomorphological processes are supposed to be responsible for the polygenesis of the paleosols, alongside of the differences in the paleoenvironment and the local geomorphological position. Erosional processes could be more intensive during the beginning of interglacials along the slope, when vegetation was sparse but precipitation increased. On the other hand, it is presumed that sedimentation decreased locally, during glacial periods, because the strong winds carried away the deposited dust. These paleoenvironmental features may well have led to the partial erosion of paleosol horizons and the lack of or entire alteration of thin loess formed during the glacials, therefore the successive paleosol formed on the previous one. The case study shows that although the polygenetic development of paleosols disrupts the clear chronostratigraphical subdivision of the section, it can nonetheless provide valuable information about the sequence evolution.