engleski

Clay mineralogy, a useful tool for the identification of a double layer soil profile

Eluvial and illuvial horizons of a pseudogley on flat terrain, primary, middle deep, distric at Laudonov Gaj locality were analysed by X-ray powder diffraction (XRD). The mineral composition of the following size fractions was analysed: <2 mm, 63-125 μm, 32-63 μm, 2-32 μm and clay fraction (<2 μm). The dominant mineral phases in eluvial and illuvial horizons are quartz and mixed-layer clay minerals. Samples also contain micaceous minerals (including illitic material), kaolinite (well and poorly crystallised kaolinite), potassium feldspar, plagioclase, goethite, amorphous matter, possibly chlorite and vermiculite. In the eluvial horizon, the amount of quartz is almost twice the amount of quartz in the illuvial horizon. In contrast, the amount of clay minerals in the illuvial horizon is twice the amount of clay minerals in the eluvial horizon. Compared to the illuvial horizon, the eluvial horizon is enriched in potassium feldspar. The clay fraction of the eluvial horizon is dominated by mixed-layer clay minerals, presumably interstratified chlorite-vermiculite. It also contains significant amounts of kaolinite minerals (approximately similar amounts of both well crystallised and poorly crystallized kaolinite), illitic material and vermiculite. The clay fraction of the illluvial horizon is dominated by mixed-layer clay minerals and kaolinite minerals. The amount of the irregularly interstratified chlorite-vermiculite dominates over regularly interstratified chlorite-vermiculite. The share of poorly crystallised kaolinite is substantially higher than the share of well crystallised kaolinite. This fraction also contains illitic material, and, possibly, irregularly interstratified illite-smectite. The diffraction lines of chlorite and vermiculite are also discernible, but it cannot be taken for granted due to their very low content. It is important to stress that the 2-32 μm and 32-63 μm fractions of the illuvial horizon contain kaolinite minerals. The same fractions of the eluvial horizon do not contain kaolinite minerals. The diffraction lines of dolomite in the 32-63 μm fraction of the eluvial horizon are visible. This mineral phase was not observed in the same fraction of the illuvial horizon. Given the great texture contrast between the two horizons and the differences in their mineral composition, it can be assumed that the proluvial deposit could be the source material for the development of younger sediments, which were later, as a coarse textured material, deposited on the soil formed on proluvial clays, and the double-layer soil profile was formed.

Clay mineralogy; double layer soil profile

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