No 1 (2024)

As life progressed, there were a small number of key evolutionary innovations that initiated global biosphere change. One such event was the explosive development of terrestrial vegetation and the emergence of forest ecosystems during the Devonian period. The colonization of land begun by bryophytes and their ancestors required the appearance and development of a variety of root systems. Roots evolved separately and independently in several main directions, rapidly expanding their functionality and complexity. In the middle Zilma river on the Middle Timan in the red-colored sediments of the Middle and Upper Devonian numerous paleosoil horizons and their complexes were studied. According to palynological data in this territory the terrestrial flora was highly diverse. The studied ancient soils are distinguished by the presence of insitu roots of various types. The purpose of the work was a morphological description of the discovered root systems. The taxonomy of Devonian root systems today is in the period of primary data accumulation. As a result of studies three morphological types of root systems belonging mainly to grass-like plants have been identified in paleosoils. There are no descriptions of such objects in paleobotanic literature. Morphological types of root systems are correlated with geomorphological features of the studied territory.

The paper deals with the fossil cyanobacterial films from the Lower Proterozoic shungites (Livvian) of the Republic Karelia, Russian Federation. The films were previously described as a formal species Cyathotes nigoserica Makarikhin. These films were formed by bacteria and possibly by fungi, which existed in condition of littoral or supralittoral (zone of stochastic wave drops reaching, or splash zone, spray zone). The adaptation of these organisms for existence in temporally (possibly, long-temp) dry conditions is evidenced by development of their outer dense covers predicting against dehydration of the organism body. This basically bacterial community intensively influenced onto the mineral substrate and had changed its structure enriching the soil by biogenic chemicals/constituents and thus forming an archaic paleosole microprofile. The signs of ancient soil formation found in the course of research can be considered the transformation of the surface texture of the mineral substrate by the vital activity of terrestrial organisms (bacteria, fungi) with the formation of a specific cellular relief, a change in the internal structure of this substrate with the appearance of casts of wedge-shaped cracks in the underlying matrix, the redistribution of inorganic compounds during the formation of a paleosurface microprofile (an increase in the content of silicon oxide in the upper part profile with simultaneous reduction of the amount of iron oxides).

A detailed mineralogical and geochemical study of the reference section “Otkaznoye”, representing a loess-soil complex confined to the Tersko-Kuma Plain, was carried out. The section provides a detailed record of the history of the development of the region in the Pleistocene. The thickness of the deposits reaches up to –140 m, and the age can exceed 800 thousand years. One of the main tasks of the work was to demonstrate the capabilities of a set of methods of environmental magnetism in combination with Mössbauer spectroscopy, mineralogical and geochemical methods for carrying out paleogeographic reconstructions of the natural environment and sedimentation conditions in the Pleistocene. Changes in the main magnetic properties for the Otkaznoe section were found, indicating with a high sensitivity of iron mineralogy in conection to climatic conditions during soil formation and sedimentation. The soil horizons are characterized by an increased content of ferrimagnets. There is a significant increase in the ferrimagnetic contribution in paleosol horizons (PS), where it reaches 80% of the total magnetic susceptibility compared to loess horizons, where its share is 5060%. The distribution of clay minerals over the depth of the studied section makes it possible to distinguish up to six levels of development of paleosols. The degree of manifestation of changes in the mineral composition in them is different. An important point is the presence of chlorites in the paleosol horizons, which can probably be explained by the erosion of the most weathered top of the PS. A noticeable increase in the content of the smectite phase in the PS horizons indicates a sufficient duration of soil formation. The results obtained on the change in magnetic and clay mineralogy quite clearly fix the paleosol horizons, but two interstadials are also distinguished – the Mikulin (MIS5) and the Dnieper (MIS6) (probably weakly pronounced Bryansk paleosol), which confirms the stratigraphic constructions. ased on the obtained set of magnetic and mineralogical, and geochemical parameters for the soil-loess complexes of the territory of the Terek-Kuma Plain, the dynamics of climatic conditions in the Pleistocene is quantitatively reconstructed and the trend of gradual climate aridization during the Pleistocene is confirmed. The epochs of interglacials, when soil complexes were formed, were characterized by an increased, compared to the stages of glaciations, climate humidity with a maximum aridity index IDM -35 (annual precipitation up to 700 mm) characteristic of the Inzhava pedocomplex (PS4).

Structure and properties of MIS3 and MIS2 cryopedolith material indicate the general similarities in synlithogenic pedogenesis that took place during those stages. On the other hand, some differences are determined by the intensity of pedogenic processes, plant cover, rate of mineral material deposition, climatic conditions. During MIS3 stage, four epigenic (buried) soils had been formed. The lowest one (4^th) was formed in the very beginning of MIS3 stage under the relatively favourable climatic conditions and with no mineral material deposition. 2^nd and 3^rd buried soils had been formed in the middle of MIS3 under the less favourable conditions and with no mineral matter deposition as well. The upper one (1^st) buried soil was formed in the transition period between MIS3 and MIS2 under the increasing of the climate conditions severity and the soil has both sinlithogenic and epigenic features in its morphology.

In 2011, the Ryshkovo pedolithocomplex of the Mikulino Interglacial (MIS-5e), consisting of three or four soil profiles separated by humus pedosediments, was studied in the Alexandrov quarry (Kursk, Russia). The lower soil is eroded gray, the two middle ones are meadow soils at the bottom of the coastal ravine, the middle one on the paleoslope is soddy-podzolic, and the upper poorly developed soils with elements of forest soil formation. Morphological, physicochemical, and microbiomorphic study of the pedolithic complex on the slope and in the bottom of the buried coastal ravine filled with colluvial and alluvial-colluvial deposits made it possible to reconstruct at least three or four pedogenic and four morpholithogenic stages in MIS-5e, which significantly detailed the event history of the interglacial. In the profile of the Ryshkovo pedolithocomplex, a buried humus horizon of the lower gray soil is well expressed, reflecting the warmer climatic conditions of the first half of the last completed interglacial compared to the second half. Soil formation in trans-accumulative landscapes was repeatedly interrupted by erosion-accumulative processes, which reflects the instability (rhythmicity) of the climatic situation during the Mikulino (Eem) interglacial and correlates well with other detailed records of geological archives.

Soils buried under burial mounds (kurgans) of the Middle Ages (12^th–13^th centuries AD) and surface soddy-podzolic soils (Retisols) in the Odintsovo district of the Moscow region have been studied. In the buried soils, differences were recorded in signs of the processes of waterlogging and/or podzolization, as well as in morphological data – humus accumulation and biological activity. The surface soil shows the most light-colored profile with deep tongues of bleached material. Based on the data of microbiomorphic analysis, a relative chronological order of the kurgans construction in the necropolis is proposed. At the beginning of the 13^th century AD a relatively warm and humid climatic conditions under which the soil buried under kurgan 3 was formed have been reconstructed, similar to those of the last thirty years, but with extreme weather events in the form of severe winters and anomalous precipitation years (no more than 5–10 years in a row), and relatively dry and cold climate in the second half of the same century, when the soil under kurgan 1 was formed. The study confirmed the variable nature of the climate in the forest zone of the Moscow region during the last completed climatic rhythm of the Holocene. An approach for the construction of kurgans has been determined: soil horizons from ditches around the kurgan was laid in reverse order on the cut surface of the buried soil and tamping the soil without additional moisture. The results obtained supplement the database of the information block of ancient forest soils under the kurgans.

The soils buried under the early medieval mounds of the 9th and early 11th centuries have been studied. The reconstruction of the influence of natural changes in the natural environment on the dynamics of soil formation processes was carried out on the basis of a comparative analysis of the properties of soils buried under mounds of different ages, day (background) and newly formed on mound structures; supplemented with data on the time of soil formation on sandy soil-forming rocks in the taiga zone. The study area belongs to the Baltic province of soddy-podzolic soils of the southern taiga subzone. Soils buried under mound structures during periods with different climatic conditions are described. Soils that developed before burial in a cool and humid climate of the 8th-9th centuries. AD, are characterized by the mobility of iron forms along the profile and a morphologically pronounced accumulation of bleached quartz grains in its upper part. The influence of the warm and dry climate of the X century. AD on the processes of soil formation is manifested in the lower mobility of iron compounds and more active humus accumulation, less clarification of mineral grains. The time of formation of the profile of soddy podbur in the material of mound structures is estimated at 1 thousand years. The construction of the mound structures consisted in successive filling of the shaft from the edges to the center of the site, in which the material of the middle horizons of the original soil turned out to be in the upper part of the mound.

Based on the example of an exposure at Cape Maly Chukochi, a model was developed for the accumulation of the soil-sedimentary sequence of the ice complex of the Kolyma Lowland. The distribution of the magnetic susceptibility of the sediment over the depth of the sequence is measured, which has a periodic shape. The specific magnetic susceptibility of the material at the level of (5–25) × 10⁻⁸ m³_/kg is determined by the presence of fine magnetite crystals in it. The hypothesis is substantiated that the finely dispersed magnetite of the ice complex is of authigenic origin. Due to its accumulation, the magnetic susceptibility of the soil increases during the lifetime of the material in the seasonally thawed layer, and its distribution in the soil-sedimentary sequence contains information about the history of the sequence accumulation. The proposed model describes the soil-sedimentary sequence because of sediment ingress to the soil surface with a time-varying intensity of the sedimentary matter flow, which determines the dynamics of the sediment lifetime in the seasonally thawed layer and the period of magnetite accumulation in the soil. The calculated distribution of the sediment transformation degree in the sequence profile is compared with the measured distribution of magnetic susceptibility. Based on the data on the distribution of magnetic susceptibility, the model was used to reconstruct the accumulation history of the soil-sedimentary sequence.