Material composition of embriozems developing on dumps of iron ore deposits in the south of Western Siberia

Nowadays the problem of industrial impact on natural landscapes is one of the most critical. It is urgent for regions of the south of Western Siberia where large-scale industrial and resource centers are concentrated. The aim of this research was to study material composition of man-made soils developing on dumps of iron ore deposits in the south of Western Siberia. The research objects were man-made soils (embriozems) of the Odrabash deposit transport dumps (53°12'23'' N, 87°17'53'' E) included in the Temir-Telbesskiy group of iron ore deposits. We carried out petrological analysis of the rocky part of embriozems by the method of polarization microscopy of sections specially made from fragments of rock formation. We studied the mineralogical content of the samples with the help of X-ray phase analysis using the X-ray diffractometer X»Pert PRO (PANalytical). The diffractograms were decoded with the help of PDF-4 and HighScore software. The diagnostics and identification of minerals in the analysis of X-ray patterns were carried out according to basal reflections (for targeted formulations) and their interplanar distances. We revealed that, in contrast to forest-steppe and steppe zones, there is prevalence of three embriozem types (initial, organo-accumulative, sod) which differ in degree of severity and maturity of organogenic horizons in soils of man-made landscapes of the Odrabash iron ore solid mass of the taiga mining belt. In comparison with background brown taiga mining soils, a specific particularity of embriozems is a higher rockiness (See Table 1) which determines adverse water regime and low actual fertility potential. In the petrographic respect, dump rocks where embriozems are formed are represented mainly by clinozoisite and actinolite metasomatite (See Figure 3). The Odrabash iron ore deposit has contact metasomatic origin in the class of the magnetite-magnesian-skarns. The studied embriozem types are similar in qualitative and quantitative content to minerals. In embriozem rock matrix, crystalline silica is the main primary mineral (See Table 4), which is explained by the silicate nature of the majority of rock-forming minerals in the studied territory of the iron ore deposit; minor minerals are represented by typical rock-forming minerals of the Altai-Sayan mountainous country: grossular (andradite group), kozulit (amphibole group); rare minerals are zeolite, ferric oxide and micas (mostly potash mica). Such a small content of finely-divided mica in matrix soil is an indicator of relatively recent processes of mineral weathering of overburden and enclosing rocks that appeared on a daylight surface as a result of technogenesis. The main iron-containing minerals are brassil and ferric oxide. We found out that mineral content of montmorillonitic group increases from initial embriozems to sod ones in the evolutional range of man-made soils, which indicates intensification of structure-forming processes in this direction. We established that material composition differences between natural landscape soils and those formed at corresponding geochemical positions of anthropogenic landscapes of the same area are determined by several factors. Among such factors the leading role belongs to particularities of maternal matrix composition, age resulting in different degrees of embriozem profile development, and chaotic mineral distribution in embriozems caused by anthropogenic impact. The obtained results of material composition along with other parameters make it possible to carry out geographical and genetic analysis of relationships between development particularities of a particular embriozem type and determining factors and conditions of soil formation, as well as to assess soil-ecological state of anthropogenic landscapes. The article contains 3 Figures, 4 Tables and 31 References.

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