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We present data on dispersed gold and associated disseminated mineralization of leucogranites controlling the location of the Dukat epithermal Au-Ag deposit. The data suggest the formation and burial of small portions of oversaturated gold-bearing fluids in hypabyssal magmatic bodies. The lower (relative to silver) contents of gold in the deposit ores and the high Ag/Au ratios (350-550) are due to the limited occurrence of oxidized gold-bearing fractions of magmatogene fluids. This limitation is explained by the active interaction of late magmatic portions of fluids and the material of the host carbonaceous volcanosedimentary unit and by the formation of an environment favorable for the concentration, migration, and deposition of manganese, silver, and nonferrous-metal compounds.

We present results of petrographic, mineralogical, and geochemical study of all types of rocks of a multiphase pluton and consider the chemical evolution of igneous and metasomatic rocks of the Baga Gazriin Chuluu pluton, based on new precise analytical data. At the early stage of their formation, the pluton granites were already enriched in many trace elements (Li, Rb, Cs, Be, Nb, Ta, Th, and U), F, and HREE relative to the upper continental crust. They show strong negative Ba, Sr, La, and Eu anomalies, which is typical of rare-metal Li-F granites. The geochemical evolution of the Baga Gazriin Chuluu multiphase pluton at the postmagmatic stage was marked by the most intense enrichment of greisens and microclinites with lithophile and ore elements (Sn, W, and Zn) and the formation of ore mineralization. In the permeable rift zone where the Baga Gazriin Chuluu pluton is located, the fluid-magma interaction took place under the impact of a mantle plume. High-temperature mantle fluids caused melting of the crustal substratum, which determined the geochemical specifics of Li-F granite intrusions. Genesis of granitic magma enriched in Li, F, Rb, Sn, and Ta is possible at the low degrees of melting of the lower crustal substratum. The Baga Gazriin Chuluu pluton formed in the upper horizons of the Earth’s crust, where magma undergoes strong differentiation and the saturation of fluids with volatiles can lead to the postmagmatic formation of metasomatites of varying alkalinity (zwitters (greisens), microclinites, and albitites) producing rare-metal mineralization. By the example of the early Mesozoic magmatism area of Mongolia, it is shown that the formation of granites and associated rare-metal minerals is due to the interaction of mantle fluids with the crustal material and the subsequent evolution of granitic magmas.

The Nd isotope composition of ferromanganese deposits (FMD) from the central part of the Sea of Okhotsk and the Kuril island arc has been studied. The results showed that diagenetic samples from the Deryugin Basin have a heterogeneous Nd isotope composition. The positive ε_Nd values here might be both due to the input of a terrigenous impurity and due to diffuse endogenous element supply. The FMD samples from the Sonne underwater ridge show a ε_Nd value specific to seawater (-3.2). The ε_Nd value of hydrogenetic FMD from Volcano 7.14 is -3.4, which corresponds to the ε_Nd value of the Pacific water. The FMD samples from Volcano 5.5 are characterized by ε_Nd = -2.0. The higher ε_Nd value might be due to a moderate dilution of the hydrothermal fluid by seawater and might also indicate the presence of volcanic fragments in the FMD samples. The highest ε_Nd value (+4.4) has been established for volcaniclastic sandstone saturated with Fe and Mn hydroxides. It points to a mixing of volcanomictic and hydrothermal materials.

In the northern Ladoga area, the age of the Sortavala Group rocks in the southeast of the Raahe-Ladoga zone of junction of the epi-Archean Fenno-Karelian Craton and the Paleoproterozoic Svecofennian province, their relationship with dome granitoids, the age of the provenances, and the time of metamorphic processes were estimated. The study was focused on the Nd isotope composition of rocks, the geochemical and isotope-geochronological parameters of zircon from the granite-gneisses of the Kirjavalakhti dome, the basal graywackes of the lower unit and the trachytes of the middle unit of the Sortavala Group, and the plagio- and diorite-porphyry dikes cutting the volcanosedimentary units of this group. The new isotope-geochemical data show a Neoarchean age of the granitoids of the Kirjavalakhti dome (2695 ± 13 Ma) and their juvenile nature (ε_Nd( T ) = +1.5). The granitoids underwent tectonometamorphic transformations (rheomorphism) in the Paleoproterozoic (Sumian) (2.50-2.45 Ga), which are recorded in the U-Th-Pb isotope system of the rims of the ancient cores of zircon crystals. The volcanosedimentary complex of the Sortavala Group formed on the heterogeneous polychronous (3.10-2.46 Ga) continental crust of the epi-Archean Fenno-Karelian Craton. With regard to the errors in determination of the age of clastic zircon, the minimum concordant U-Th-Pb ages of 1940-1990 Ma of detrital zircon from volcanomictic graywackes of the Pitkyaranta Formation can be taken as the upper age bound of terrigenous rocks, which agrees with the maximum age of the Sortavala Group rocks estimated from the U-Th-Pb (SIMS) age of 1922 ± 11 Ma of the Tervaoya diorites (Matrenichev et al., 2006). According to the proposed new tectonic model, the accumulation of the volcanosedimentary complex of the Sortavala Group, its metamorphism, erosion, and overlapping by the Ladoga Group turbidites had already occurred in the pericratonic part of the epi-Archean Fenno-Karelian Craton by the time of the Svecofennian continent-island arc collision, subduction, and formation of bimodal volcanoplutonic complexes of the young Pyhäsalmi island arcs and felsic volcanics of the Savo schist belt (1920-1890 Ma).

The paper concerns the sediment sequence, which is widespread in the Yenisei valley and in the Tuva and Minusa depressions and also present in the valleys of the southern Chulym plain. The sediments of this sequence were previously described as “Neogene mud-shedding”, as well as moraines, alluvial fan deposits, alluvium of Middle Pleistocene high terraces, and lacustrine sediments. The giant ripple marks on the Upper Yenisei terraces was commonly interpreted as ribbed moraines; however, in recent studies, these ridges have been repeatedly referred to as marks of giant current ripples. Besides, some recently published papers provide description of geology of this sequence fragments suggesting its deposition by cataclysmic floods. Geomorphological analysis of the area shows Pleistocene glaciers to have been localized within the medium-high mountainous areas. The glaciers did not reach the Tuva and Minusa depressions and occupied large areas only in the Todzha basin and on the periphery of the Darkhat basin, forming a glacial dam at its outlet, which resulted in glacial-dammed lakes filling the basin completely. These lakes outburst, and the resultant flooding led to the deposition of megaflood sediments, which we refer to here as the Upper Yenisei sediment sequence. A detailed analysis of its facies architecture revealed similarity of these sediments to those of the Sal’dzhar and Inya sequences in Gorny Altai. Most of the Upper Yenisei megaflood sediments are localized in topographic lows of the Tuva and Minusa depressions. Beyond the Altai-Sayan mountainous area, the megaflood sediments of the Upper Yenisei sequence compose high terraces of the Yenisei, Chulym, Chet’, and Kiya rivers in the southern Chulym plain. The formation of Upper Yenisei sequence dates to the first half of the Late Pleistocene, inasmuch as it contains inset alluvial sediments of the second terrace of the Yenisei River. The available data allow suggesting that the Upper Yenisei sequence formed in the first Late Pleistocene regional glaciation. The Sal’dzhar sequence in Gorny Altai and the fourth terrace of the Ob’ River on the Fore-Altai plain are stratigraphic analogs of the Upper Yenisei sequence. The Upper Yenisei and Sal’dzhar sequences can thus be considered future regional markers serving as a link for the local stratigraphic schemes of the Altai-Sayan mountainous area and adjacent West Siberian plains. The results obtained call for verification by geochronological dating, first of all, by modern luminescence dating methods covering a wider chronological interval than radiocarbon dating.

We consider the geologic structure of the Nerunda gold ore field located in the Nerunda-Mama ore district in northern Transbaikalia. Gold-quartz low-sulfide formation and ore-bearing carbonate-terrigenous strata and intrusive complexes are briefly described. An ore complex of beresite-listvenite metasomatites hosting carbonate-quartz veins and vein-veinlet zones is characterized. Two stages of ore formation have been recognized. Anomalous geochemical associations and the composition of ore mineralization typical of these stages have been established. Mineralogical and geochemical studies of gold-bearing metasomatites of the Nerunda ore field were carried out. The known geochemical and mineralogical search criteria used for the assessment of the erosion zone level of gold deposits were applied to the geologic conditions of the Nerunda ore field and the Nerunda-Mama gold ore district as a whole. The emphasis was made on the express assessment of the erosion zone level at the early stage of prospecting. We draw a conclusion about the gold potential of the poorly studied ore objects at depth and give guidelines for the following geological exploration.

The compositions of volatile components in cordierite, tourmaline, and quartz from pegmatites of the Kuhilal deposit were studied by pyrolysis-free gas chromatography-mass spectrometry (GC-MS), IR and Raman spectroscopy, and microthermometry, and their comparative analysis was performed. Capillary GC-MS was applied to determine the component composition and relative contents (rel. %) of volatiles from different zones of crystals and fractions of cordierite. It has been established that water and carbon dioxide prevail among them. Hydrocarbons are predominantly aliphatic, cyclic, and oxygenated. Heterocyclic, nitrogenated, and sulfonated compounds are present in gas-liquid inclusions in tourmaline and quartz, and volatile components are localized in both structural cavities and nonstructural positions in cordierites.

The paper presents results of a petrogeochemical and isotope-geochronological study of the granite-leucogranite association of the Pavlov massif and felsic volcanics from the Elash graben (Biryusa block, southwest of the Siberian craton). A characteristic feature of the granite-leucogranites is their spatial and temporal association with vein aplites and pegmatites of the East Sayan rare-metal province. The U-Pb age of zircon from granites of the Pavlov massif (1852 ± 5 Ma) is close to age of the pegmatites of the Vishnyakovskoe rare-metal deposit (1838 ± 3 Ma). The predominant biotite porphyritic granites and leucogranites of the Pavlov massif show variable alkali ratios (K₂O/Na₂O = 1.1-2.3) and ferroan (Fe^*) index and peraluminous composition; they are comparable with S -granites. The studied rhyolites of the Tagul River (SiO₂ = 71-76%) have a low ferroan index, an increased K₂O/Na₂O ratio (1.6-4.0), low (La/Yb) _n = 4.3-10.5, and a clear Eu minimum (Eu/Eu^* = 0.3-0.5); they are similar to highly fractionated I -granites. All the coeval Later Paleoproterozoic (1.88-1.85 Ga) granites and felsic volcanics of the Elash graben have distinct differences in composition, especially in the ferroan index and heavy REE content, owing to variations in the source composition and melting conditions during their formation at postcollision extension. A wide range of isotopic parameters of granites and felsic volcanic rocks (ɛ_Nd from +2.0 to -3.7) and zircons (ɛ_Hf from +3.0 to +0.8, granites of the Toporok massif) indicates the heterogeneity of the crustal basement of the Elash graben, which formed both in the Archean and Paleoproterozoic.

An assessment is made of the lake resources of Russia in particular regions identified on the basis of the genetic principle, i. e. an approximate even-aged origin of most lake basins within the territory. It was determined that a little less than two-thirds of all water bodies are located on the coastal plains of the seas of the Arctic and Pacific Oceans, which account for one-fifth of the country’s area. The climatic conditions of the coastal zone are favorable for the existence of lakes, most of which owe their origin to relatively recent (on a geological time scale) marine transgressions. The total water surface area of the coastal plains makes up about 40 % of the total area of all water bodies of Russia; however, they contains only 1.3 % of the total water volume of the country because most of these water bodies are shallow. The territories that were previously under the cover of the Valdai glaciation occupy about 4 % of the country, their water surface area is about 18 %, and the number of water bodies located there makes up 6 % of the total number for Russia. The lakes remaining on the site of the Valdai glaciation contain more than 5 % of the total volume of the country’s waters. About 90 % of the entire lake waters are concentrated in mountainous regions, where a significant part of the deepest and most capacious lakes including Baikal are located, but the number of water bodies is only 5.6 % of the total number in the country, and the water surface area is 13 %. It is shown that since the origin of the lakes is primarily determined by the geological history of the region, their distribution over the territory is rather weakly dependent on climatic factors. An increased lake percentage is observed in regions that had ridded themselves of sea waters and glacial cover at the interface of the Lake Pleistocene and the Holocene; within these regions, changes in lake percentage are governed by differences in sculptural landforms.

A natural resource zoning of the Far Eastern macro-region within the boundaries of the modern Far Eastern Federal Dis trict (Okrug) has been carried out. The zoning is based on identifying territorial combinations of natural resources from the presence of two types of inter-resource links: direct and indirect links of resource-containing components in natural geosystems, and indirect links of resource-containing components through components of territorial socio-economic systems that are formed in the process of extraction and development of natural resources. The following algorithm for natural resource zoning was worked out and used. On the basis of physical-geographical zoning, a relatively integral natural geosystem is identified, in which resource-containing components are distinguished, including areas of land and forest resources. Next, geosystem inter-resource links are determined, including the links of certain natural resources with the largest ones. As a result, the territorial combinations of natural resources existing in this natural geosystem are revealed. After that, the inter-resource relations, formed in the process of extraction and use of certain natural resources through transport links and settlements, are determined. Taking them into consideration, the more complete territorial combinations of natural resources as the basis for natural resource areas are distin guished. In coastal areas, in-land natural resources can be interrelated with marine natural resources. This means that the maritime boundaries of such areas remain open.