Geochemistry of ultramafic–alkaline rocks of the Ziminsky complex (on the example of the Bol’shetagninsky and Beloziminsky massifs) (Eastern Sayan)

The paper compares the elemental composition of alkaline silicate rocks of the Bol’shetagninsky and Beloziminsky massifs, which are part of the Ziminsky complex of ultrabasic rocks and carbonatites. The rocks of the Bol’shetagninsky massif belong to the potassium series and are distinguished by increased concentrations of large ionic lithophilic elements; in the rocks of the Beloziminsky massif, the rocks of the sodium series predominate and the contents of highly charged elements are increased. Judging by the lack of correlation between the highly charged elements in alkaline and subalkaline rocks of the Bol’shetagninsky massif, their formation, in contrast to the rocks of the Beloziminsky massif, is not associated with the process of fractional crystallization.

Platinum-Group Minerals in the Placer of the Kitoy River, East Sayan, Russia

The platinum-group minerals (PGM) in placer deposits provide important information on the types of their primary source rocks and ores and formation and alteration conditions. The article shows for the first time the results of a study of placer platinum mineralization found in the upper reaches of the Kitoy River (the southeastern part of the Eastern Sayan (SEPES)). Using modern methods of analysis (scanning electron microscopy), the authors studied the microtextural features of platinum-group minerals (PGM), their composition, texture, morphology and composition of microinclusions, rims, and other types of changes. The PGM are Os‑Ir‑Ru alloys with a pronounced ruthenium trend. Many of the Os‑Ir‑Ru grains have porous, fractured, or altered rims that contain secondary PGE sulfides, arsenides, sulfarsenides, Ir-Ni-Fe alloys, and rarer selenides, arsenoselenides, and tellurides of the PGE. The data obtained made it possible to identify the root sources of PGM in the placer and to make assumptions about the stages of transformation of primary igneous Os-Ir-Ru alloys from bedrock to placer. We assume that there are several stages of alteration of high-temperature Os-Ir-Ru alloys. The late magmatic stage is associated with the effect of fluid-saturated residual melt enriched with S, As. The post-magmatic hydrothermal stage (under conditions of changing reducing conditions to oxidative ones) is associated with the formation of telluro-selenides and oxide phases of PGE. The preservation of poorly rounded and unrounded PGM grains in the placer suggests a short transport from their primary source. The source of the platinum-group minerals from the Kitoy River placer is the rocks of the Southern ophiolite branch of SEPES and, in particular, the southern plate of the Ospa-Kitoy ophiolite complex, and primarily chromitites.

To the hoverflies fauna (Diptera: Syrphidae) of the high mountains of Eastern Sayan in Siberia

A list of 101 species of hoverflies recorded from three high altitudinal belts in the Eastern Sayan mountain region is given. Most species belong to the subfamilies Syrphinae (60 species) and Eristalinae (38 species), while Pipizinae and Microdontinae are presented by two and one species, respectively. Totally, 96 species were found in the forest zone, 37 species were found in the mountain tundra and only Platycheirus chilosia has been caught in the golsty belt. New synonymy is established: Melangyna arctica (Zetterstedt, 1838) = Melangyna soszynskii Mielczarek, 2013 syn. n., = Melangyna tsherepanovi (Violovitsh, 1965) syn. n.

Chemical component depositions in the microbial mats and travertine in the Khoito-Gol thermal spring (Eastern Sayan)

The results of studies of the chemical composition of water, travertine, and microbial mats in the Khoito-Gol mineral spring (Eastern Sayan) are presented. It was shown that the formation of mineral deposits, travertine, and microbial mat is connected with the active functioning of microorganisms and geological and geodynamic conditions. It has been revealed that the diversity of cyanobacterial and sulfur microbial mats increases as the distance from the springs of the thermal water grows. Microbial mats are hardened with carbonates being converted into solid travertine crusts that are built upon the top of older structures to form multi-meter domes. The concentration function of the microbial mats and thermal water showed higher coefficients of accumulation of nickel and beryllium.

Spatiotemporal Structure Features of a Pine Stand on the South Slope of the Eastern Sayan Mountain

Due to relatively long development and long life of forest-forming species most of the conclusions on stand dynamics are based on the data collected by indirect methods of comparative research and analysis of cenosis forming theoretically temporal and spatial succession sequences and need to be verified and clarified. The most reliable results on the stand dynamics can be received on stationary objects such as permanent sample areas. The article presents the analysis results of long-term monitoring (1968–2012) of a pine (Pinus sylvestris L.) stand in low-mountain Eastern Sayan on the south slope with a steepness of 7–8º. The intermittent test of morphometric indicators of trees mapped on the permanent sample area was used. It is shown that the sum of tree trunk cross-section areas at breast height (1.3 m) varied by no more than 10 % with timber reserves on the lower, central and upper equal sites of the sample area during the entire observation period. At the same time heterogeneity of ecological conditions, taking place even on a small section of a smooth slope, influences the plantation self-thinning intensity. In the 42-year-old stand density ratio at lower, central and upper sites was 1:1.5:2.1. Stand density difference along the slope had been decreasing gradually over time, although it remained around 30 % at the time of the last observation. Over the years of observation, 53, 47, and 32 % of pines on the lower, central, and upper sites, respectively, have survived. The calculated average age of the died trees showed that in all groups of natural diameter classes, there was an earlier die-off of pines at the bottom of the slope with an increase in dying age up to the slope. Trees with larger trunk diameter (first telling) died later. All this led to a rearrangement of the horizontal structure of the plantation, a decrease in the average diameter and average volume of trees up to the slope. Typical for mountain forests clinal tree distribution, which affects their morphological indicators, is important to consider when studying and modeling forest ecosystems, as well as when implementing forest management measures. For citation: Ovchinnikova N.F. Spatiotemporal Structure Features of a Pine Stand on the South Slope of the Eastern Sayan Mountains. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 5, pp. 34–47. DOI: 10.37482/0536-1036-2021-5-34-47

INFORMATION MODEL OF THE ECOTOURISM TERRITORY OF THE CENTRAL PART IN THE EASTERN SAYAN

In information modeling, it is important to determine the content, direction and form of information flows. Information flows of environmental education are formed in the visitor center, distributed across the territory of ecotourism and are aimed at forming an ecological mentality among various groups of visitors to the territory of ecotourism. The information system of environmental education and enlightenment, which forms a responsible attitude of tourists to their natural environment, is integrated into the tourist framework of the territory. The decomposition of the network of tourist routes in the Central part of Eastern Sayan made it possible to determine the field of influence of information centers and to identify the main characteristics: the general theme of expositions, environmental routes, a set of functions and architectural style. The territory of ecotourism is considered as a social space. The power of influence of information objects depends on their position in the social space, which is determined by the size of their social capital. The methodological approach to modeling the information content of the ecological and educational visit center is the concept of the social field of P. Bourdieu, where the ecological field seeks to maximize its influence. The institution that exerts this influence is the educational system. As a result, the author proposed a conceptual model of the environmental education system, the essence of which is that the content of the main theme of the visit center should correspond to its field of influence.