Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 13. 1987. (Budapest, 1987)

3. At about 500-600°C there is the endothermal peak of clay minerals. Rarely it appears at 480°C. The curves show the presence of illite, probably an illite-montmorillonite mixed-layer clay mineral. The mixed-layer structure might be responsible for the appearance of adsorption water at the beginning of the DTA curves in a double peak, altough the second peak is almost invisible. An exothermal peak also appears above 800°C, characteristic for montmorillonite. However, the characteristic peak of pure montmorillonite between 680 and 700°C does not appear. The asymmetrical form of the endothermal peak between 500 and 600°C also indicates mixed-layer structure. The appearance of the quartz peak at 570°C, indicating transformation of alpha to beta quartz, does not make our work easier in determining the clay mineral. If there is coarse-grained organic matter in the sample (e.g. root fragments), it burnt out at higher temperatures only, causing the spreading of the organic matter peak over 500°C; it partly compensated the clay mineral peak on the DTA curve and increased it on the DTG curve. In this case the organic matter - clay mineral boundary was determined artificially at 500°C, and quantitative interpretation was carried out considering this distribution. 4. Over 600°C thermal dissociation of carbonates begins. Downwarping branch of the endothermal peak of the carbonates always starts with a moderate slope; also, on the DTG curve there is a gradually quickening weight loss only. The peak terminates with a steep upwarping section. On the registrates of samples treated by dilute HCl this flat endothermal section starting at 600°C could not be observed. Consequently, we can postulate that dissociation of the finest, weakly crystallized calcium-carbonate, forming a film-like coating observable by the naked eye, occurs at this temperature. The better crystallized calciumcarbonate leaves from 700°C onwards. In some cases there is a definite weight loss around 700°C, before the main peak of calcite, observable on the DTA curve, too, and the typical peak of calcite appears around 800°C only. The peak around 700°C can be attributed to the magnesium content of calcite. In other cases presence of dolomite could be proved if the double carbonate peak was easily observed. All peaks were considered as carbonates between 600 and 750°C, but we are aware that less characteristic montmorillonite and chlorite peaks may occur in this interval having no significant effect on quantitative relationships. Fig. 9 shows some characteristic derivatograms. Clay mineral content of the samples ranges between 5 and 40%, average value being 20%. The quantity of organic matter is a few percent. Of course most of it is in level A, gradually decreasing downwards, reaching almost zero in the subsoil. Change of carbonate content in the profiles where it attains considerable quantities, shows a more or less regular pattern. In these profiles there is almost no carbonate in level A, it increases suddenly at 40-60 cm depth and it can be followed downwards by a further 6080 cm. Below it suddenly decreases. In meadow soil (26) and alluvial meadow soil (29) profiles carbonate content does not exceed 1-3%. The quantities of organic matter, clay minerals and carbonates determined by derivatograph are given in Table 2. Optical emission spectrometry Qualitative and semi-quantitative analysis was carried out to determine trace element occurrences. Samples were pulverized in an achate ball-mill down to silt size. The powder was put into aluminium electrodes and placed into an ISZP-29 medium dispersion quartz spectrograph applying alternating current arc induction. Gevaert Scientia 23 D 56 photographic plate was applied for registration, developed for 5 minutes in TÖRÖK's developing bath at 20°C, The following elements were determined: Mn, Zn, Cu, Pb, Ga, Cr, Ni, Co, Ti, V, Ba, Sr, B. As our method has given only semi-quantitative data, the results are applicable only for the characterization of average trace element content of the investigated area. Interpretation within the profiles and correlation among profiles could be made in a very general manner only. The interpretation is based on the data of VINOGRADOV (1950) and AUBERT and PINTA (19 77). The spectrometry data are listed in Table 3. A^ng_anes_e Mn-content of soils ranges from 50 to 8 500 ppm, average value is 1 000 ppm. Our re-