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Talajképződési folyamatok rekonstrukciója morfológiai, talajtani és ásványtani vizsgálatok alapján egy visontai paleotalaj szelvényében

Berényi Üveges, Judit, Németh, Tibor, Michéli, Erika, Tóth, Mária
Agrokémia és talajtan 2002 v.51 no.3-4 pp. 325-340
Chernozems, Fourier transform infrared spectroscopy, Vertisols, X-ray diffraction, calcium carbonate, clay, clay fraction, eluviation, forest soils, lignite, loess, mineralogy, mountains, paleosolic soil types, Hungary
Investigation aiming the reconstruction of soil forming processes in a representative paleosol profile was carried out in the open lignite mine located at Visonta (pediment of the Mátra mountains, Hungary). The sequence of layers of the studied wall consists of a present day chernozem brown forest soil on top, a red paleosol, a bioturbated layer and two grey clay layers. Samples from identified layers and horizons were examined by chemical and mineralogical methods (XRD, FTIR, DTA). The characteristics of the red paleosol (structure, presence of „slickensides”, high clay content, smectitic mineralogy, high layer charge of smectites etc.) indicates that the dominant soil forming process was periodic shrinking and swelling of the clays. It correlates very well with the features described in present day Vertisols (FAO–UNESCO, 1998) in several parts of the world. The parent material of the red paleosol at Visonta seems very likely to be the red clay formed in the Mátra Mountains. This red clay was eroded off, reworked, mixed with other sediments, (e.g. loess) and deposited on the site. The evidence on the influence of loess or loess like material is the presence of chlorite and its usual alteration products towards vermiculite, moreover the presence and the characteristics of the calcium carbonate concretions. The present day state was reached as the result of several different processes: the periodical shrinking and swelling of the clays which indicates changes of wet and dry periods, eluviation and precipitation of carbonates, frost effects, and periodical freeze and thaw, bioturbation, reworking of materials and erosion. Most of them reoccurred periodically, consequently they over-printed each other.