Sofia Lessovaia - Academia.edu (original) (raw)

Uploads

Papers by Sofia Lessovaia

The transformation of primary and secondary minerals in a recent shallow soil (Haplic Cryosol (Re... more The transformation of primary and secondary minerals in a recent shallow soil (Haplic Cryosol (Reductaquic)) from a highly weatherable ultrabasic rock (serpentinous dunite) of the mountainous tundra of the Polar Urals was determined. Primary and secondary mineral associations were analyzed in thin sections, by electron microscopy, X-ray diffraction, IR-spectroscopy, and thermal analysis. The susceptibility of the fresh rock for weathering was characterized by the micromorphology of the connective pores. Disintegration of the rock resulted in relatively high amounts of inherited olivine, serpentine, talc, and chlorite in the fine soil. Element release from fresh mineral surfaces exposed also in internal pore systems of rock fragments is a decisive factor for the appearance of secondary minerals in the fine soil. Secondary minerals are two smectites, saponite and nontronite, and vermiculite. Especially the silicates rich in Mg, olivine and serpentine with lower contents in the b 1 mm fraction of the soil horizons in comparison with the fresh rock, are the most probable sources for saponite. The source of nontronite is not fully understood. It is supposed that olivine and serpentine and/or pyroxenes that are allochthonous for serpentinous dunite and inherited from harzburgite affect their formation in the soil. Most probably vermiculite is the result of chlorite transformation. Content of smectites decreases in the upper horizons of the soil whereas in an opposite trend, vermiculite increases. Supposedly biota, especially moss and lichens, have a strong contribution to silicate weathering which leads to saponite and nontronite decomposition and chlorite transformation despite neutral to alkaline pH-values in the whole soil. Relatively high amounts of dithionite and oxalate soluble Fe indicate a marked release of Fe by silicate weathering. For element release freezing in the permafrost environment seems to have a decisive role by affecting pore systems in the rock and the soil skeleton fraction.

CATENA, 2014

ABSTRACT Recent soils from basic (amphibolite and meta-gabbro amphibolite) and ultrabasic (serpen... more ABSTRACT Recent soils from basic (amphibolite and meta-gabbro amphibolite) and ultrabasic (serpentinous dunite) rocks formed in cold and humid climates of Northern Eurasia (Russia) were studied to detail the characterization of soils and rocks with special attention to the interdependence of porosity system and rock mineralogy. The study plots were located in taiga and tundra zones of East Fennoscandia and the Polar Ural Mountains. A variety of methods was used including optical microscopy, X-ray diffraction and Rietveld analysis, and three supplemental methods for the determination of pore space characteristics in rocks: (i) mercury intrusion porosimetry, (ii) a modification of this method using the intrusion of a molten alloy (Wood's metal), and (iii) scanning atomic-force microscopy. The results illustrate that the specification of the porosity system is a significant factor in tracing the clay mineralogy in soils formed from hard rocks. Ultrabasic rock is the most sensitive to weathering, as determined by (i) the high value of small pores, especially those with a radius of < 10 nm, (ii) the elongated form of the pores and surface roughness, and (iii) zones with an accumulation of phyllosilicates in regions with higher porosity causing the formation of soil enriched by clay minerals. Despite the presence of low proportions of phyllosilicates in both types of basic rocks, only soil from meta-gabbro amphibolite is enriched by clay minerals and is most probably affected by small pores (< 10 nm). The absence of phyllosilicate accumulation along the pores and the predominantly empty space inside the pores indicates the limitation of potential sources of phyllosilicates for developing soils from meta-gabbro amphibolite. Insignificant phyllosilicate accumulation in shallow soil from amphibolite, in which the fine size fractions are mostly the result of rock disintegration, is supposedly due to a particularly narrow pore size distribution with a predominance of pores between 100 and 1000 nm.

Quaternary International, 2006

This study investigates the iron oxide chemistry and mineralogy of two relict paleosols, a Ferri-... more This study investigates the iron oxide chemistry and mineralogy of two relict paleosols, a Ferri-Endostagnic Lixisol (Bathiplinthic) and a Profondi-Endostagnic Luvisol (Chromic). The estimated inception of their pedogenesis is Early Pleistocene. The two paleosols belong ...

Journal of Soils and Sediments, 2014

Eurasian Soil Science, 2012

Gravelly clay loamy and clayey soils developed from the derivatives of ultramafic rocks of the du... more Gravelly clay loamy and clayey soils developed from the derivatives of ultramafic rocks of the dun ite-harzburgite complex of the Rai Iz massif in the Polar Urals have been studied. They are represented by raw humus pelozems (weakly developed clayey soils) under conditions of perfect drainage on steep slopes and by the gleyzems (Gleysols) with vivid gley color patterns in the eluvial positions on leveled elements of the relief. The magnesium released from the silicates with the high content of this element (mainly from olivine) specifies the neutral-alkaline reaction in these soils. Cryoturbation, the accumulation of raw humus, the impregnation of the soil mass with humic substances, gleyzation, and the ferrugination of the gleyed horizons are also clearly pronounced in the studied soils. Despite the high pH values, the destruction of supergene smectites in the upper horizons and ferrugination (the accumulation of iron hydroxides) in the microfissures dissecting the grains of olivine, pyroxene, and serpentine, and in decomposing plant tissues take place. The development of these processes may be related to the local acidification (neutralization) of the soil medium under the impact of biota and carbonic acids. The specificity of gleyzation in the soils developing from ultra mafic rocks is shown in the absence of iron depletion from the fine earth material against the background of the greenish blue gley color pattern.

Eurasian Soil Science, 2011

Permafrost affected palevye (pale) soils of Central Yakutia are developed from mantle calcareous ... more Permafrost affected palevye (pale) soils of Central Yakutia are developed from mantle calcareous deposits of different textures and are characterized by the common mica-chloritic association of clay min erals with a higher content of chlorite in comparison with the soils developed from mantle loams and loess like loams in the European part of Russia. In the pale soils, the distribution of clay minerals in the profile has an even pattern in the loamy variants and a differentiated pattern typical of podzols in the loamy sandy vari ants. Data on the chemical extracts and Mössbauer spectroscopy indicate that the iron in the pale soils is mainly fixed in silicate minerals. The content of nonsilicate iron represented by the amorphous and weakly crystallized compounds in the pale soils is relatively low. The humus accumulative horizon in these soils is close to the gray humus (soddy) AY horizon according to its acid-base characteristics (the soil pH and the degree of base saturation) despite the presence of exchangeable sodium and the shallow occurrence of the cal careous horizon.

Eurasian Soil Science, 2008

Soil formation on hard rocks-nepheline syenite, amphibolite, metamorphized gabbro diabase, and th... more Soil formation on hard rocks-nepheline syenite, amphibolite, metamorphized gabbro diabase, and their derivatives-was studied in the mountainous tundra and in the northern and middle taiga zones of the Kola Peninsula and Karelia (in the Kivach Reserve). It was found that the soils developing from these rocks could be classified into three groups: (1) petrozems with the O-M profile (the most common variant), (2) podzols and podzolized podburs on the substrates with an admixture of morainic derivatives of acid rocks, and shallow (<5-10 cm) pebbly soils on the substrates without an admixture of allochthonous material (the rarest variant). In soils of the third group, the pedogenic alteration of the mineral matrix does not result in the appearance of phyllosilicates in the fine fractions if these phyllosilicates are initially absent in the rock. In these soils, the processes of modern pedogenesis (rock disintegration, migration of Al-Fe-humus compounds, in situ transformation of the organic matter, and binding of iron released from the weathered silicate minerals into iron-organic complexes) are virtually undifferentiated by the separate soil horizons because of the very low thickness of the soil profiles. These soils have the Oao-BHFao-M profile; it is suggested that they can be classified as leptic podburs. An admixture of morainic material containing phyllosilicate minerals favors a more pronounced differentiation of the modern pedogenic processes by separate soil horizons even in the case of shallow soil profiles; the intense transformation of phyllosilicates takes place in the soils.

Applied Clay Science, 2012

Applied Clay Science, 2014

Pore space issues and mineral paragenesis of traprocks from the central part of the basaltic prov... more Pore space issues and mineral paragenesis of traprocks from the central part of the basaltic province (Central Siberia, Russia) were studied, as was the fine size fraction (b1 μm) of well-drained soils from two groups -"shallow with hard rock" and "deeper and mature with saprolite." The explanation of coexisting of these two groups was given via rocks' characteristics. The methods used included mercury intrusion porosimetry (MIP), impregnation of connective pores with a molten alloy (Wood's metal) combined with subsequent electron microscopy, optical microscopy, X-ray diffraction, and IR spectroscopy. Rock from the lithic contact is represented by slightly weathered dolerite and shows a tendency to bimodal pore size distribution with a second maximum in pore size at 10 nm, which is due to the occurrence of phyllosilicates. Coarse pore systems are mainly due to cracks, which allow an easy exchange of water. Higher total porosity in the rock in one of two pits (~12 vol.% compared with 4 vol.%) appears to be a prerequisite for the formation of a deeper and more mature profile. Secondary products of dolerite weathering are smectites determining the association of clay minerals in both soil profiles and Fe-oxides. Most likely, desegregation and weathering of the rock fragments from soil horizons are fast enough to keep sufficient amounts of smectite only in the fine size fraction of the shallow profile. In the mature profile, pedogenesis leads to acidification of upper soil horizons and to a pronounced decrease in the smectite proportion, not only in the soil but also in the rock fragments from soil horizons. Thus, smectite(s) that was stable in early stages of rock weathering and soil formation and became unstable due to soil acidification illustrates the metastable nature of clay mineralogy in the well-drained soils from basic rock.