Search

This article presents new data on the ionic, microcomponent, and isotope compositions of thermal waters of the Amgu group classified as sodium-bicarbonate waters with low mineralization (up to 0.2 g/L), high contents of silica (up to 24 mg/L), lithium, tungsten, and molybdenum, and pH = 8.5–9.7. The influence of neotectonics and Quaternary magmatism on the composition and conditions of formation of nitrogen–siliceous thermal waters is shown. Using δD and δ18O values in thermal and background waters, their atmogenic origin was proved, and the source area of mineral waters was identified. The calculated deep reservoir temperature of 77–81°С indicates the formation of water resources in the crust at significant depths (as much as 2.5 km). The efficiency of using the multicomponent geothermometry method for low-temperature reservoirs is shown. [ABSTRACT FROM AUTHOR]

The Vuoriyarvi Devonian carbonatite-ijolite-pyroxenite-olivinite complex comprises several carbonatite fields: Neske Vara, Tukhta-Vara, and Petyayan-Vara. The most common carbonatites in the Tukhta-Vara and Neske-Vara fields are calciocarbonatites, which host several P, Fe, Nb, and Ta deposits. This paper focuses on the Petyayan-Vara field, in which the primary magmatic carbonatites are magnesian. The least altered magnesiocarbonatites are composed of dolomite with burbankite and are rich in REE (up to 2.0 wt. %), Sr (up to 1.2 wt. %), and Ba (up to 0.8 wt. %). These carbonatites underwent several stages of metasomatism. Each metasomatic event produced a new rock type with specific mineralization. The introduction of K, Si, Al, Fe, Ti, and Nb by a F-rich fluid (or fluid-saturated melt) resulted in the formation of high-Ti magnesiocarbonatites and silicocarbonatites, composed of dolomite, microcline, Ti-rich phlogopite, and Fe-Ti oxides. Alteration by a phosphate-fluoride fluid caused the crystallization of apatite in the carbonatites. A sulfate-rich Ba-Sr-rare-earth elements (REE) fluid (probably brine-melt) promoted the massive precipitation of ancylite and baryte and, to a lesser extent, strontianite, bastnäsite, and synchysite. Varieties of carbonatite that contain the highest concentrations of REE are ancylite-dominant. The influence of sulfate-rich Ba-Sr-REE fluid on the apatite-bearing rocks resulted in the dissolution and reprecipitation of apatite in situ. The newly formed apatite generation is rich in HREE, Sr, and S. During late-stage transformations, breccias of magnesiocarbonatites with quartz-bastnäsite matrixes were formed. Simultaneously, strontianite, quartz, calcite, monazite, HREE-rich thorite, and Fe-hydroxides were deposited. Breccias with quartz-bastnäsite matrix are poorer in REE (up to 4.5 wt. % total REE) than the ancylite-dominant rocks (up to 11 wt. % total REE). [ABSTRACT FROM AUTHOR]

The mineral composition, distribution and fractionation of rare-earth elements in dissolved and suspended forms (solid residue) of atmospheric precipitation were studied by analyzing the snow sampled over urbanized territory by the example of the city of Blagoveschensk. Electron-microscopic studies revealed the own minerals of rare-earth elements in dust aerosols. It is shown that the main sources of the atmospheric pollution by rare-earth elements were emissions of TPP (heat and power plants) and boiler houses. Contrasting geochemical anomalies of rare-earth elements were found in the snow cover of the city. The REE concentrations in the solid phase of snow are few orders of magnitude higher than those of the liquid phase. The snow solid phase provides insight into the REE behavior, because it directly reflects the impact of different anthropogenic sources. The characteristic feature of the REE distribution in the solid residue of snow is their LREE enrichment relative to MREE and HREE. The average HREE content is 10% of total REE. In the snow water-solid phase system, most samples show weak fractionation between LREE and HREE owing to the low total mineralization of the snow liquid phase and the small content of organic matter. [ABSTRACT FROM AUTHOR]

The paper considers for the first time the morphology, composition, and conditions of formation of the greisens of the Solnechnoe deposit (Komsomol'sk ore district), a typical cassiterite-silicate assemblage. The greisens are localized in the root parts of the deposit and represent a system of veins and veinlets formed in the contraction fractures of the metasomatically altered roof of the monzogranite intrusion (age of 94-92 Ma). The cassiterite-chlorite-carbonate-muscovite-quartz composition of the greisens with admixture of topaz, fluorite, and apatite reflects the composition of the monzogranites. The greisens are close in age (85.3 Ma on muscovite) to the granitic aplites (80-85 Ma on the whole-rock and biotite) of the final phase of the intrusive magmatism. The fluid regime of their formation differs from that of the economic ores in higher temperature, pressure, and salinity. One distinguishing feature of the greisens is elevated contents of LREE, U, and Th, which are incorporated in the REE fluorcarbonates, thorite, and uranothorite crystallizing together with cassiterite. [ABSTRACT FROM AUTHOR]

Data on the concentrations of rare-earth elements and other metals in oils from Sakhalin fields were obtained by inductively coupled plasma mass spectrometry. The chemical preparation of the samples included the stages of acid digestion and ashing. In terms of the total metal contents; V, Ni, and Fe ratios; and Sr isotope ratios, the oil samples are divided into three groups. The crude oils from the extreme northeastern part of the island shelf, which are assigned to group I, differ from the other oils in the high contents of V and other metals, as well as the high V/Ni and V/Fe ratios. The crude oils of the group II fields located southward have elevated contents of REE and some other lithophile elements and moderate V/Ni and V/Fe ratios. Group III fields from the same area and from the Tatar Strait have low metal concentrations and low V/Ni and V/Fe ratios. The Sr/Sr ratio is comparatively low in the group II oil (0.70838-0.70858) and elevated in the group III oil (0.70854-0.70911). The Sr isotope ratio of the crude oils of the Kaigan-Vasyukan deposit (group I) originated from marine organic matter (0.70867-0.70884) is correlated with Sr/Sr ratios in sea-water with an age of 18.0-10.5 Ma. Based on the REE patterns, the V/Ni ratios, and the results of the multielement factor analysis, the crude oils of group III and, to a lesser extent, of group II are similar to the West Siberian crude oils. [ABSTRACT FROM AUTHOR]

The chemical composition of the bottom sediments of the Amur River has been analyzed using modern analytical techniques. It was found that their composition and distribution patterns are controlled by several sources. The most probable sources for the bottom sediments of the studied area are siliceous magmatic or metasedimentary rocks. [ABSTRACT FROM AUTHOR]

Abstract: The Bulka intrusion, a standard intrusion of the Bulka complex, is localized in northeastern West Sayan. The layered series is composed of dunites, melanotroctolites, troctolites, olivine gabbro, gabbro, hornblende gabbro, olivine leucogabbro, olivine leucogabbronorites, leucogabbro, hornblende leucogabbro, leucotroctolites, anorthosites, and plagioclase-bearing hornblendites. The Mg-number (Mg#) varies from 76 in peridotites (38 wt.% MgO) to 34 in anorthosites (2 wt.% MgO). From bottom to top of the section, the following crystallization sequence of liquidus minerals is observed: Ol ⇒ Pl ⇒ Cpx ⇒ Opx ⇒ Amph + Mag. The petrochemical features of the intrusion rocks are consistent with the fractional crystallization of picritic parental magma (24 wt.% MgO, 11 wt.% FeO, Mg# = 80). The compositions of model cumulates determined by fractional crystallization modeling using the COMAGMAT 3.5 computer program at 1–2 kbar, QFM buffer, and 0.5 wt.% H2O in the melt are similar to those of the Bulka intrusion rocks. The REE and trace-element patterns for these rocks show a nonfractionated composition trend with LILE and HFSE depletion. The LILE patterns are similar to those in N-MORB, which evidences that the parental magma was produced through the partial melting of the oceanic lithospheric mantle probably similar to the adjacent ophiolites of the Kurtushiba belt. The HFSE depletion of the intrusion rocks might be due to the island-arc processes during the belt formation. The Bulka intrusion formed at the accretion-collision stage of magmatism as a result of the differentiation of picritic melt generated from the oceanic lithospheric mantle with superposed island-arc processes. [Copyright &y& Elsevier]

Abstract: Geochemical studies of the ecosystems of 184 Siberian lakes in three largest zones of northern Asia (humid, arid, and semiarid) and in mountainous area were carried out. The contents of natural radionuclides, radiocesium, and rare-earth elements in conjugate components of the systems and the types of the main sources of the bottom sediment material have been determined. Dating of the bottom sediments was made by the activity of radioisotopes 137Cs and 210Pb, which permitted estimation of the sedimentation rates in lakes in different regions of Siberia: 0.35 cm/year in the south and 0.25–0.3 cm/year in the north. Six main ions have been determined in the waters of the studied lakes: Ca2+, Mg2+, Na+, HCO3 −, SO4 2−, and Cl−. The distribution of natural radionuclides in the stratified sections of bottom sediments of Siberian lakes evidences the stable sedimentation and characterizes their contents in the soils of water-catchment areas, which can be considered background contents there. Sediments enriched in organic matter have higher concentrations of U and lower ones of Th and K. The Th/K ratio in the studied bottom sediments is the same as in the soils. The Th/U ratios are somewhat lower than those in the soils because U is accumulated by chemogenic and organic components. The overall 137Cs pollution of bottom sediments of Siberian lakes is close to the global background (40 mCi /km2 in 2000), but in the Altai Territory and Buryatia and Altai Republics it is twice higher. The uneven areal and temporal distribution of residual radiocesium is observed not only in the lacustrine sediments but also in the lake water areas. The REE patterns of bottom sediments of different mineral types are similar to those of continental crust and clays of the Russian Platform, though organogenic and carbonate sediments have higher absolute REE contents than terrigenous ones. Pelitic fraction is the main REE concentrator in the bottom sediments. [Copyright &y& Elsevier]

Abstract: The meteoritic-material-normalized REE patterns of rare-metal granite intrusions of the ore-bearing Kukul''bei complex (J2–J3), eastern Transbaikalia, were studied. It is shown that the intrusions were initially enriched in granitophile volatiles and trace elements (rare metals), i.e., this phenomenon is not related to the differentiation of their parental magma chambers. On the differentiation of the Kukul''bei rare-metal intrusions, the REE contents decrease in passing from granites of the main intrusive phase (MP) to late leucocratic differentiates (muscovite and amazonite granites), the differentiates become more enriched in granitophile elements, and their rare-metal contents drastically increase as compared with the MP granites. The ore-bearing bodies of muscovite and amazonite granites have extremely low REE contents and the highest contents of granitophile (including ore-forming) elements. The REE patterns of the Kukul''bei intrusive differentiates are not universal among rare-metal intrusions. By the example of highly ore-bearing rare-metal granite intrusions of the Erzgebirge, Central Europe, it has been established that their late deep-seated differentiates (ultrarare-metal lithionite-zinnwaldite Li-F-granites) accompanied by highly productive Sn-W mineralization concentrate both granitophile elements and REE (particularly HREE). Among the studied Transbaikalian rare-metal intrusions of the Kukul''bei complex, only the differentiates of the most ore-bearing Sherlovaya Gora intrusive system belong to the above type. The analysis of the REE patterns of the Kukul''bei granites confirmed the earlier conclusions on the low ore potential of the rare-metal mineralization of the studied intrusive complex. [Copyright &y& Elsevier]

With resources estimated at 1100 t Au at an average grade of 2.45 g/t, the black shale-hosted Sukhoi Log noble metals deposit is the largest concentration of gold in Russia. The Au mineralization and associated platinum group element (PGE) mineralization of the Sukhoi Log deposit is controlled by a tectonic zone along the axis of an overturned anticline located in metamorphosed carbon-bearing Upper Proterozoic sedimentary rocks. Organic compounds have been carbonatized by hydrothermal fluids. The centro-symmetric zoning of the mineralization is typical of infiltration metasomatism whereas disseminated and veinlet gold deposits accompanied by a quartz, carbonate, and pyrite assemblage were superimposed on sedimentary rocks. Nearly 90 minerals occur at Sukhoi Log including native metals, intermetallic alloys, sulfosalts, phosphates, tungstates, and oxides. Native gold is the main one mineral, but calaverite, hessite, petzite, and krennerite also occur. PGE mineralization is located on the periphery of the gold mineralization in the form of native platinum, Pt–Cu–Fe metal alloys, sperrylite, and cooperite. The mineral assemblage also includes native Fe, Cr, Cu, Ni, Sn, W, Ti, and Te, as well as alloys of these metals. The ore-forming process involved fluid temperatures of 130–395 °C, pressures of 0.2–2.4 kbar, and salt concentrations of 3.7–9.5 wt.% NaCl equiv.Mineralogical, geochemical, and geophysical studies were used to develop a three-stage genetic model of the deposit involving deposition of terrigenous and carbon-bearing terrigenous-carbonate rocks in an intraplate rift about 800 Ma followed by regional metamorphism at 520 Ma culminating in the development of palingenetic granites and hydrothermal fluids transporting contrasting assemblages of elements—(Cr, Ni, Ti, Pt+Pd) and (Sn, W, Mo, Zr, Au, Ag, Zn+Pb)—at 320 Ma. [Copyright &y& Elsevier]

The Raman spectra of Tomtor samples contained the goethite (Gth) and apatite (Ap) show a 1520 cm-1 band of the carotenoid in cyanobacteria. A slight shift of this band is observed in the range from 1517 to 1520 cm-1 in the apatite containing samples depending on the compositions of carotenoids, the ratio of the rare earth elements adsorbed by cyanobacteria as well as their interaction with environment. Samples of rock from the Tomtor Nb - REE (rare-earth elements) deposit (Russia) have been investigated by Raman micro-spectroscopy using visible 532 nm wavelength excitation. Raman spectra of different samples of this rock confirm their composition as calcites and other carbonates such as rhodochrosite, and mixed solid solution phases (Ca, Mn, Fe, Mg, Ba, Sr, REE)(CO 3). An association between cyanobacteria and the apatite crystals has been noted Cyanobacteria exhibited Raman modes at 1520–1517 cm−1 located in the double bonds of the central part of the polyene chain of carotenoids. A slight shift of this mode in the apatite-containing samples are dependent upon the compositions of carotenoids, the ratio of the rare earth elements adsorbed by cyanobacteria as well as their interaction with the environment. Laser-induced photoluminescence of REE and Mn+2, obtained as an analytical artifact in the Raman spectra, has been observed in most cases with significant spectral intensity. The luminescence emission of Mn 2+, Sm3+, Eu 3+, Pr3+, Ho3+, Er 3+ in the spectra of the apatite-containing samples obtained with 532 nm excitation can be attributed both to apatite and to other mineral phases with a low concentration which contain these elemental ions. The results obtained in this study allowed us to confirm that the biogenic presence of the cyanobacterial mat had a significant impact on the formation of the unique Nb-REE Tomtor deposit. [ABSTRACT FROM AUTHOR]

One of the potential sources of rare-earth elements (REE) is the industrial waste known as red mud (bauxite residue), in which the majority of REE from the initial bauxite are concentrated via the Bayer process. Therefore, the studies of the subject, both in Russia and outside, focus almost exclusively on red mud processing. This article looks into the possibility of REE concentration into red mud by leaching an intermediate product of the bauxite sintering process at Russian alumina refineries, namely electrostatic precipitator (ESP) dust. The experimental works were performed by X-ray diffraction (XRD)and electron probe microanalysis (EPMA) of the sinter and sinter dust. The determination of major and rare-earth elements in the sinter from the rotary kilns and in the ESP dust before and after leaching was carried out by X-ray fluorescence (XRF) and plasma mass spectrometry (ICP-MS). The study showed that it is possible to obtain red mud that contains three times more REE than traditional waste red mud after two-stage leaching ESP dust in the water at 95 °C followed by leaching in an alkaline-aluminate liquor at 240 °C. The shrinking core model was used to study the kinetics of leaching of the original ESP dust and water-treated dust in alkaline-aluminate liquor. The study showed the change in the limiting stage of the alkaline leaching process after water treatment, with the activation energy growing from 24.98 to 33.19 kJ/mol. [ABSTRACT FROM AUTHOR]