THE PEDOGENESIS OF SOME GIBBSITIC SOILS FROM THE SOUTHERN UPLANDS OF SCOTLAND

The mineralogy of ten profiles developed from hornfelsic rocks on the summit areas of the Merrick and Kells Hills has been investigated by X-ray powder diffraction, thermal, infra-red, and optical methods. The soil clays of the C horizons of all profiles contain 6 to 37 per cent of gibbsite but this mineral is not found in the A horizons. Optical observations reveal that gibbsite is associated with hematitic rock fragments which are considered to represent older soil material–i.e. are pedorelicts. It is suggested that the Merrick soils are polygenetic and consist of two soil stratigraphic units, recent pedogenic effects being superimposed on a basal horizon that has been strongly influenced by preglacial or interglacial weathering.     

Basic features of late pleistocene soil formation in the east european plain and their paleogeographic interpretation

Large-scale climate fluctuations reflected in the alternation of glacial and interglacial epochs have resulted in structural changes in the landscape shell. Differences in heat and moisture supply have accounted for specific features of soil-forming processes, zonality structure, and the ratio of soil formation and sedimentation processes. The sequence of types of soil formation epochs is most completely reflected in the structure of loess-soil cryogenic formations, where specific features of soil formation and sedimentation during no less than seven natural climatic macrocycles (over the past 800 ka, the Brunhes paleomagnetic epoch) have been revealed and analyzed. Within macrocycles, three main types of soil formation epochs have been distinguished: interglacial, interstadial, and pleniglacial (interphasial). Interglacial soil formation evolved from subtropical in the Eopleitocene and Early Pleistocene to subboreal and boreal in the Middle and Late Pleistocene. Interstadial dark-colored soils developed during early interstadial warmings at the beginning of glacial epochs and formed complexes with interglacial soils. Pleniglacial soil formation was characteristic of the coldest phase of the Valdai glaciation, when sedimentation and physical weathering absolutely prevailed over soil formation, leading to the development of specific synlithogenic soils. In the periods of climate softening, interstadial soils of cryo-gley genesis were formed.     

Genesis and age of mineralogical profiles of Moldavian chernozems

In chernozems developed in the autonomous positions in Moldova, the mineralogy of their silicate component has some features indicative of stronger transformations than those that could be expected for the chernozems formed by the Holocene pedogenesis. The mineralogical profiles testify to the eluvial nature of the main subtypes of chernozems. It is suggested that the revealed changes are not due to the Holocene pedogenesis. According to the probable age of the mineralogical profiles calculated from the volumes of aluminosilicates removed, these profiles originated in the early and middle Late Pleistocene, i.e., about 50 000–120 000 years ago. The effect of forest pedogenesis in the past epochs on the mineralogy of the northern subtypes of chernozems also cannot be excluded. The presented data characterize the chernozems under study as polygenetic soil formations.     

Specificity of the morphology of interglacial and interstadial paleosol complexes of the middle and late Pleistocene in the center of the East European Plain

Paleosol studies were conducted on the Moskva-Oka interfluve in the center of the East European Plain. Three paleosol complexes were distinguished in the sequence of soil-loess deposits: the Mezin complex of the Late Pleistocene age and the Kamensk and Inzhavin complexes of the Middle Pleistocene. Each of them consisted of the paleosols of two phases: the earlier interglacial phase and the later interstadial phase. In some cases, the paleosols of these two phases were separated by a thin layer of sediments with distinct features of cryoturbation. Paleosols of the interstadial phases are represented by the dark-colored humus-rich meadowchernozemic and chernozem-like prairie soils. During the interglacial periods in the Middle and Late Pleistocene, the soils with pronounced eluvial-illuvial differentiation of their profiles were developed under forest cenoses. Data on the morphology of paleosols; their physical, chemical, and physicochemical properties (particle-size distribution, pH, humus, carbonates, amorphous and crystallized iron oxides, etc.); and their micro-morphological features studied in thin sections prepared from undisturbed soil monoliths make it possible to judge the character of the pedogenesis during different epochs.     

西藏高原土壤多元发生的微形态研究

自上新世末以来,随着西藏高原的隆起和多次冰川作用,作为成土因素的气候、植被、地形、水文等条件发生了剧烈的演变,从而对西藏高原土壤的发生、演化产生重要的影响.土壤大形态研究表明,西藏高原土壤广泛地显示有明显的组合剖面,突出表现在这些土壤剖面中存在有黄棕或棕带红色的、与其上下土层无发生上联系的、在暖湿气候条件下形成的土层;或者在某些现代陆成上壤剖面中存在有水成土的残遗特征等,这些形态特征在很大程度上说明了西藏高原土壤多元发生的客观存在.     

Morphological and chemical properties of the meadow-semidesert soil complexes of the Khaki playa (the Caspian Lowland) and the influence of the biogenic factor on them

The initial stage of the development of the complex soil cover pattern in the Caspian Lowland was studied. The obtained data made it possible to reveal the specific features of the morphological and chemical properties of the soils on terraces of the Khaki playa and the role of burrowing animals in the formation of the microtopography and complex soil cover patterns on the youngest surfaces. The soil cover of the studied area consists of three-component complexes: light-humus quasi-gley solonetzes on relatively flat background surfaces, zooturbated solonetzes on microhighs, and humus quasi-gley soils in microlows. The layered deposits of the Khaki playa terraces and the shallow depth of the saline groundwater are responsible for the specificity of the modern salinization of the studied solonetzes. The distribution of the salts in their profiles has a sawshaped patter, which is related to the nonuniform texture of the deposits. On the microhighs composed of the earth extracted from 5- to 7-year-old suslik burrows, specific zooturbated solonetzes are formed. The known age of these formations makes it possible to determine the rate of the desalinization of the gypsum- and salt-bearing material extracted onto the soil surface and the rate of the salt accumulation in the lower part of the solonetzic horizon and in the subsolonetzic horizons in comparison with the data on the solonetzes of the background flat surfaces. The specific features of the soils in the closed microlows suggest that these soils have a polygenetic origin. The features of the recent hydromorphism predetermine the specificity of their morphology.     

Genesis of light-colored acid eluvial horizons in soil profiles

General ideas concerning the formation of light-colored acid eluvial horizons in soil profiles are considered. In Russia, the current concept is related to the polygenetic origin of these horizons due to processes of acid hydrolysis, lessivage, and gley. Based on the original and literature data summarized by the author, the conclusion was drawn that the acid hydrolysis cannot provide the reduction of Fe (III) to Fe (II) under aerobic conditions or its further transfer to the soil solution. Lessivage, which governs the formation of light-colored acid eluvial horizons, is not an obligatory factor, as its features are often absent in the profile of these soils. Under conditions of a stagnant-percolative water regime, gley may be considered to be the only process responsible for the eluviation of Fe, Mn, and Al and removal of iron hydroxide and iron oxide coatings from mineral grains, resulting in an increase in the relative Si content and the appearance of a whitish color. This factor is the only cause for the formation of light-colored eluvial (podzolic) horizons. Therefore, they are monogenetic in origin.     

Specific features of soil formation in the taiga zone of Western Siberia

Specific features of soil formation in the taiga zone of Western Siberia are considered. The polygenetic nature of podzolic and gley-podzolic soils in the middle taiga zone, soddy-podzolic and soddy gley soils in the southern taiga zone, and meadow soils in the subtaiga zone is related to the pre-Holocene transformation of the lithogenic matrix upon activation of denudation and accumulation processes and the complicated Holocene evolution of these soils. A soil profile can be subdivided into separate layers according to the geomorphic features of the cryogenesis, the indices of interruption of soil formation, and the differences in the composition of the organic matter in the relict and modern humus horizons.     

Paleoclimatic implications of micromorphic features of Quaternary paleosols of NW Himalayas and polygenetic soils of the Gangetic Plains — A comparative study

Micromorphological examination of the paleosols (50–10 ka) developed in alluvial fan deposits of the NW Himalayas and the bordering polygenetic soils (mainly Holocene) of the Gangetic Plains has been used to differentiate the pedosedimentary features indicating climatic changes during late Quaternary time. The paleosols within rapidly aggrading sediments of the alluvial fans of the Dehradun valley resulted in response to the reduced rate of sedimentation and climatic changes and correspond to the MIS3 and MIS2 stages. Distinctive micromorphic features of these paleosols provided the details of the prevalent pedogenesis in response to the paleoclimatic changes during 50 ka. Microfabrics of these paleosols show reorganization of the pedality from massive and/or subangular blocky to platy and prismatic structures, strong to very strong mobilization of the plasma, different types of textural pedofeatures along with faunal activities. These pedofeatures are indicative of cold-humid climate with subsequent change to even colder but drier conditions during the last Glaciation. Comparison of the micromorphological characters of the paleosols of the NW Himalayas and the polygenetic soils of the Gangetic Plains show the same degree of soil development indicating 5–10 ka pedogenic intervals in alluvial fans of the Dehradun Valley. However, the difference in their pedofeatures is attributed to different pedogenic environments. The paleosols of the Dehradun Valley show predominance of the illuvial features with superposed impure silty clay on earlier clay pedofeatures and banded clay fabric features without any pedogenic calcium carbonate. The bordering Gangetic Plains are covered with polygenetic soils developed on stable surfaces and are < 13.5 ka. These surficial soils developed during the period marked by deglaciation and correspond to MIS1 stage. These are defined by the juxtaposition of different illuvial pedofeatures along with pedogenic calcium carbonate. This study suggests that formation of the paleosols in NW Himalayas was mainly controlled by warmer intervals during the last glaciation and the movement along the adjacent thrusts. While fluctuating climate punctuated with humid–semiarid–humid conditions played a major role during the formation of soils on the Gangetic Plains in Holocene that favoured illuviation, calcification and dissolution of pedogenic carbonates in the polygenetic soils.     

The regularities of the late Holocene soil formation in the lower don steppes

The direction and stages of pedogenesis, rate and scales of changeability, and type of evolution of chernozems in the steppes of the Lower Don are ascertained by studying the archaeological monuments of the Bronze Age, Early Iron Age, and Middle Ages. It is shown that the soil formation process was characterized by cyclicity, and evolutional soil transformations took place at the level of subtype. The paper ascertains the polygenetic character of modern chernozems, whose evolution during the second half of the Holocene was predominantly low-contrast, inheriting, and transforming. The processes forming the humus, salt, gypsum, and carbonate profiles, as well as the processes of solonetzization-desolonetzization, were the most dynamic. The fundamental differences in the genesis of different parts of the humus profile are revealed. The role of climatically pulsing solonetzicity in forming the specific Azov chernozems is for the first time ascertained.     

Soils of cryogenic subarid steppe landscapes in the Terekhol intermontane Depression of the Sangilen Upland

The soil cover of the Terekhol intermontane Depression in the Tyva Region is poorly studied. The data obtained in the 1950s do not reflect the real genetic diversity of soils and their specific character. According to these data, the soil cover was dominated by meadow-chernozemic soils under virgin steppe-like meadows. The investigations of 2007–2009 show that the disperse-carbonate chernozems, which are often solonetzic and weakly saline; the specific polygenetic dark soda solonchaks-solonetzes; and the postagrogenic chernozems, solonetzes, and agrozems are the main components of the soil cover of the depression at the present time. The described chernozems correspond mainly to the central image of southern Siberia chernozems. The investigated solonetzes are characterized by a number of evolution-genetic features that distinguish them from previously described solonetzes of Tyva and from all the solonetzic soils in the current interpretation. The chernozems and solonetzes have cryogenic features due to the cold extremely continental climate and relatively shallow continuous permafrost.     

Comparison of the results of soil profiles’ diagnostics performed in three classification systems

Three soil classification systems—the World Reference Base for Soil Resources (WRB), Soil Taxonomy, and the recent Russian system—were used for the identification of 17 soil profiles in southwestern Poland; all the systems put emphasis on the soil properties as diagnostic criteria. Different soils developed on glaciofluvial plains, loessic uplands, and in the Sudetes Mountains were classified. The best correlation between the classification decisions in the different systems was obtained for the most widespread soils owing to the similarity of the diagnostic criteria, which were essentially close although not coinciding. The most prominent divergence between the systems in both the names and the taxonomic categories of the soils was found for the polygenetic soils and for the soils developing from the lithologically discontinuous parent materials. It was also found that the diagnostic elements differ in terms of their taxonomic importance among the classification systems.     

Mineralogical composition of the clay fraction and micromorphology of the Middle and Late Pleistocene loesses and paleosols in the center of the East European Plain

The mineralogical composition of the clay fraction and microfabrics of the cryogenic soil-loess sequences of the Middle and Late Pleistocene ages have been studied near the northern boundary of loess sediments on the East European Plain. Poorly ordered mixed-layered mica-smectitic minerals with different portions of smectitic layers predominate in the clay fraction; di-and trioctahedral hydromicas occupy the second place. The clay fraction also contains chlorite, clay-size quartz grains, and feldspars. Individual smectite is present in some of the samples. Interstadial chernozem-like paleosols are specified by the higher content of clay, the maximum concentration of smectitic layers in the mixed-layered minerals, and the presence of individual smectite. The clay fraction in the profiles of interglacial paleosols is sharply differentiated: in the eluvial part, it is depleted of smectite and enriched in kaolinite, hydromica, and clay-size quartz. These features allow us to suppose that interglacial paleosols were subjected to podzolization processes. According to the mineralogical indices, Middle Pleistocene paleosols can be differentiated into those subjected to lessivage (the Kamenskii interglacial paleosol) and podzolization (the Inzhavin interglacial paleosol).     

Geomorphic implications of Pre-Wisconsin soils on the White River Plateau erosion surface of northwestern Colorado

The White River Plateau erosion surface (Miocene-Pliocene) at an elevation of approximately 2850 m (9500 ft) is dominated by weakly developed Holocene soils which commonly possess simple A-C horizonation. However, Pre-Wisconsin soils occur on the surface in isolated areas at both high and low topographic sites, most notably in Triangle Park. These Pre-Wisconsin soils consist of composite, polygenetic profiles having truncated, clayey subsoils which are overlain by stone or pebble lines, colluvium, soil creep, and probable local eolian deposits Truncation of the paleosols preceded development of the Holocene soils, which have formed on bedrock surfaces and have been superposed on the truncated, buried paleosols Soil distribution and character, in relation to structure of bedrock on the erosion surface, indicate that the surface as it now exists is structurally controlled and has a topography generated in late Tertiary to Pre-Wisconsin time.     

Stages of development and palaeogeographical inheritance of the recent soils features in the center of the Russian plain

In the article an attempt was undertaken to make palaeogeographical analysis of the history of development of the present soils in the center of the Russian plain on the basis of the soils study in a series of sections, located in different microrelief elements of the cryogenic genesis in the Bryansk region. The analysis of the data on soil morphology, chemical and mechanical composition of soils, and peculiarities of microstructure made it possible to determine that the appearance of certain features in the soils structure was predetermined as far back as during the Late Pleistocene cryogenic period; i.e. before the beginning of the Holocene (up to 10 000 y. B.P.). The studied soils are considered as polygenetic formations. Six stages of their formation were singled out.     

鼎湖山土壤有机质深度分布的剖面演化机制

根据鼎湖山森林植被带(SL)、灌丛—草甸过渡带土壤剖面(GC)有机质含量,有机质Δ14C、δ13C值,土壤粘粒含量及孢粉分析结果,研究华南亚热带山地土壤有机质深度分布特征的成因机制。结果表明土壤有机质的深度分布特征与土壤剖面的发育过程密切相关,随深度增大,有机质的来源数量不断减少,而成土时间增加,分解作用导致的有机质含量降低幅度增大,有机质含量不断减少。土壤有机质14C表观年龄随深度增加,土壤有机质δ13C值与有机质含量的深度变化具有明显对应关系,这些都是土壤剖面发育过程中有机质不同更新周期组分呈规律性分解的结果。粘粒的深度分布反映土壤剖面淋滤淀积的特点,表明土壤剖面经受了长期成土风化。土壤剖面的上述特征均为剖面发育过程中不断沉积、不断成土的结果,表明土壤剖面成土演化对于有机质深度分布具有显著制约。     

Anthropogenic transformation of soils in the Pokrovskoe-Streshnevo Park (Moscow) and adjacent residential areas

The diversity of soils within the specially protected natural territory of Pokrovskoe-Streshnevo in Moscow is discussed. The soils of this large park are not affected by the modern construction activities that delete the features inherited from the early stages of the anthropogenic transformation of soils in Moscow. They are characterized by the book-like type of soil memory, which makes it possible to trace several sequences of the anthropogenic soil transformation. The background natural soils-rzhavozems (Chromic Cambisols)—have been transformed into agrogenic soils (agrosols) and postagrogenic soils (postagrosols) under abandoned plowlands, into urbo-soils and urbanozems in the areas of former or modern settlements, and into techno-soils in the areas of active excavation works and engineering reclamation. The change in the character of the land use without the accumulation of osediments on the surface leads to the development of polygenetic soil horizons.     

应用Markov链理论定量描述区域冲积土壤质地层次的垂向变化特征

冲积土壤剖面质地层次的垂向变化是一个十分复杂的问题,长期以来都是定性描述而无法定量化,但土壤剖面的质地层次组合特点对土壤水分转化和溶质运移等具有重要影响,对其定量地描述和研究是进一步准确定量区域农田水转化和溶质运移的基础。马尔可夫链理论是用来描述随时间（空间）变化的一个离散状态序列的状态转移特性的,本文就其引入来研究冲积土壤剖面质地层次的垂向变化规律。研究结果表明,区域冲积土壤剖面质地层次的垂向变     

Iron Oxide Properties as Support to Soil Morphological Features for Prediction of Moisture Regimes in Oxisols of Central Brazil

The relation between iron oxide properties and soil morphology was tested in a catena comprised by a sequence of Anionic Acrudox, Plinthic Acrudox, Plinthic Acraquox and Typic Acraquox soils, for prediction of drainage classes and moisture regimes, in the savanna region of Central Brazil. Morphological features, as mottles, nodules and low chromas of soil matrix, with iron content increasing in the sequence matrix → mottles → nodules, are evidence of iron segregation. The polygenetic nature of these soils is interpreted from the gibbsitic-kaolinitic mineralogical composition associated to high Al goethites attributed to a former dessilication weathering stage, and low Al goethites related to a presently wetter moisture regime. The soil morphological features, the iron distribution, and iron oxide properties are products of the selective dissolution of hematite inducing a xanthization process at the upper sites, followed by dissolution of “primary” high Al-goethite and formation of “secondary” low Al-goethite in mottles and nodules at the lower sites. Iron oxide properties are useful to distinguish preteric from present features in pedoenvironments, supporting the use of morphological soil properties to predict drainage classes and estimate soil moisture regimes in low intensity pedological surveys of these regions.     

Geochemical characterization of loess-soil complexes on the Terek-Kuma Plain and the Azov-Kuban’ Lowland

The changes in the material composition of the buried soils and loesses in relation to the dynamics of the climate and sediment accumulation were studied for revealing the pedogenetic features and assessing the natural conditions in the steppe zone of the southern Russian Plain. A comparative analysis of the chemical compositions of the different-aged Pleistocene loess-soil complexes (the Otkaznoe, Port-Katon, and Shabel’skoe profiles) on the Terek-Kuma Plain and the Azov-Kuban’ Lowland was performed. An increase in the concentrations of Fe and Mn, which are intensively involved in the biological cycle, and Rb, which is accumulated due to the activation of weathering processes, was observed in the paleosols that developed in interglacial periods of activation of pedogenesis. Increased coefficients of weathering (chemical index of alteration (CIA)) = [Al/(Al + Ca + Na + K)] 100, Al/(Al + Ca + Na + Mg), Rb/Sr, and Mn/Sr), leaching (Ba/Sr), and biological activity and bioproductivity (Mn/Fe, Mn/Al) were also noted for the paleosol horizons as compared with the loess horizons. It is argued that geochemical coefficients can be used as an efficient tool in the soil and paleogeographic studies aimed at the reconstruction and refinement of the schemes of changes in the bioclimatic conditions during the Pleistocene.