Proceedings of Siberian Department of the Section of Earth Sciences of the Russian Academy of Natura

20-34

Authors: Zh.V. Seminsky

The purpose of the article is to describe the ore belts of the Baikal-Transbaikal region identified in the course of the long-term metallogenic studies. Methods. Based on the analysis of the materials on the ore content in the region metallogenic zoning has been carried out. Two taxa have been distinguished: regional metallogenic belts and ore belts which are the links of the former. The first ones we described earlier. The minerals of the ore belts are examined in connection with the description of main tectonic elements and geological complexes composing them. We did not set the task to provide a complete description of all minerals: consideration was given to the most significant and large ore objects only. This article deals with the belts of marginal continental and collision-accretionary conditions. The second part of the article (to be published in the next issue of the journal) is going to deal with the ore belts of intraplate orogenic nature. Results. Ore belts of the Baikal-Patom marginal continental metallogenic belt are located in the marginal western part and in the north of the territory. The geodynamic situation here is determined by the spread occurrence of ancient blocks of foundation (terranes) and complexes sewing and overlapping them. The main is the Neoproterozoic metallogenic epoch which is characterized by the formation of fluorite-polymetallic, pyrite-lead-zinc, uranium and gold mineralization (Pribaikalsky, Akitkansky, Tyaya-Olokitsky, Bodaibo belts). The ore belts of the Baikal-Muya and Baikal-Vitim accretionary collision metallogenic belts are located in the central part of the region (Charo-Tokkinsky, Muya and other ore belts). Large stratiform deposits of cupriferous sandstones, banded iron formations, gold-quartz, large polymetallic and fluorite deposits, which were formed during the Proterozoic, Paleozoic and partly Mesozoic metallogenic epochs are localized within their boundaries. Conclusions. The ore belts of the marginal-continental type are represented by the systems of foundation blocks with overlapping and sewing complexes where stratiform, fluorite-polymetallic deposits, gold ore deposits, uranium mineralization in ancient volcanites are formed. The accretionary collision ore belts contain the terrains of different nature, fragments of island arcs, formations of subduction and collision geodynamic environments. Large stratiform deposits of cupriferous sandstones, lead-zinc ores, banded iron formations are widespread.

48-60

Authors: I.A. Izbrodin, G.S. Ripp, D.Ts. Ayurzhanaeva, V.F. Posokhov

The Purpose of the article is investigation of isotopic and geochemical features of Kyakhta sillimanite deposit quartzites, their genesis and possibilities to be used as a raw quartz material. Methods. Quartzites and their enclosing rocks have been examined by the complex of methods including geological, geothermal surveying methods, geochemical and isotopic (O, H) studies. Results. It is determined that quartzites located in sillimanitebearing rocks (Krutoi, Traktovy-II, Glukhaya Pad, Lesnoi sections) and in gneisses (Chernaya Sopka) have similar mineral compositions. The quartzites are enriched with titanium (0.8–2.5 wt.% TiO2) and contain high concentrations of aluminum (0.2–1.45 wt.% Al2O3). The rocks are characterized with the differentiated REE distribution range. To evaluate the sources of fluids participated in ore formation the thermocriometrical studies were conducted and isotopic abundance of oxygen and hydrogen in minerals was determined. The results of the thermocryometrical investigation of fluid inclusions indicate the predominance of aqueus carbon dioxides in all types of quartzites with the insignificant role of aqueus acids of Ca, Mg chloride fluids. The isotopic composition of oxygen (δ18O % v-SMOW) in quartz (-0.3...-3.5), sillimanite (-1.1), muscovite (-3.2... -3.7), hematite (-4.2...-4.6), rutile (-6.4…-7.6) and hydrogen (δD % v-SMOW) in muscovite (-160.0....-175.3) demonstrates the participation of fluids with the contribution of meteoric waters in the formation of quartzites. According to the isotopic thermometers quartzites were formed at the temperatures of 720–600°C. Conclusions. Some parts of quartzites correspond to raw materials for the production of silica products. The presence of rutile does not hinder concentration by traditional methods of quartz beneficiation. The rutile concentrate can be used as a raw material for titanium production

70-81

Authors: Yu.N. Didenkov, Z.V. Proskuryakova

The Purpose of the article is to study the role of rifting in the formation of Baikal region natural waters. Methods. The main research methods used in the study are structural hydrogeological analysis and simulation computer thermodynamic modeling using the “Selector” software complex. Results. A formation scheme of structural and hydro-geological conditions of the Baikal region has been developed as well as a conceptual scheme and formation models of natural waters. Zoning has been performed and identified hydrogeological structures have been described. The results of physico-chemical modeling of endogenous hydrocarbon fluid evolution when lifting to the surface and discharging into Lake Baikal have been shown. Conclusions. The structural-hydrogeological analysis and thermodynamic modeling allowed to establish the possibility of the existence of an endogenous renewable source of fresh water formed as a result of degassing at the present stage of Baikal rifting development. This fact determines both the hydrosphere freshness of the region under investigation and the preservation of the unique composition of waters of the rift lakes of Baikal and Khubsugul.

90-98

Authors: E.V. Averkina, E.V. Shakirova, Yu.V. Fokin

Introduction. The drilling practice of inclined directed wells in Eastern Siberia involves different materials and reagents with defoaming and foam suppressing properties. However, different substances work selectively in different media where it is supposed to suppress foam. The efficiency of an anti-foaming agent is evaluated by the comparison results of its action with other anti-foaming agents when processing a drilling mud of a certain composition. We have conducted comparative researches aimed at the determination of the most efficient foam suppression and foam prevention performed by anti-foaming agents on a drilling mud used in the construction of producing wells on the Yarakta oil-gas condensate field. Methods. Two methods are applied in this research: evaluation of foam suppression efficiency by the method of drilling mud density variation and determination of foam prevention efficiency. Results. It has been revealed that all tested anti-foaming agents have different compatibility with initial drilling mud. It has been concluded that BauDF Antifoam and Reapen 1408 reagents have the best lubricating ability. It has been determined that the most optimum anti-foaming agent for the drilling mud of this composition is Atren Antifoam C of 1% concentration which has one of the best indicators of both foam suppression and foam prevention. Conclusions. Application of Atren Antifoam C in 1% concentration as a part of the drilling mud will allow to prevent its foaming while being prepared and prevent the adverse impact of foam on drilling equipment.

107-117

Authors: M.P. Belykh, A.Yu. Chikin, S.V. Petrov, N.L. Belkova

Purpose. The processes of biopassive detoxication are of special interest for the solution of environmental issues of detoxification of gold heap leach cyanide-bearing wastes whose detoxification period is unlimited. These processes are based on spontaneous degradation of cyanides under the influence of natural factors including the action of autochthonous bacterial community. The purpose of the work is to develop a biopassive detoxification technology of heap leach stockpiled wastes. Methods. A long-term experiment on ore mass storage under the conditions of heap leach ore pile zoning has been carried out in order to model the process of passive detoxification of gold heap leach stockpiled wastes. The content of toxic compounds in the ore mass has been determined using a chemical analysis based on standard procedures. Results. It is found that biochemical processes dominate over simple chemical oxidation during passive detoxification of the gold heap leach ore pile. Approximating biodegradation equations have been calculated for the major toxic compounds (thiocyanates and cyanides including copper and nickel cyanide complexes).The technology of biopassive detoxification of heap leach stockpiled wastes has been developed at an industrial heap leach site of the Sakha Republic (Yakutia) deposit. Water balance of the heap leach installation and detoxification time for the major mass of the ore pile have been calculated. Process circuit and process flow diagram of the proposed technology have been developed. Conclusions. The introduced technology eliminates the costs for reagent detoxification and is based on high economic and environmental efficiency as compared to conventional chemical technology. Introduction of additional modernizations of the irrigation circuit as well as removal and transportation of snow will be carried out at low capital and operational costs. The expected economic potential of the technology of bipassive detoxification of gold heap leach site will be 151429.7 thousand roubles