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To gain insight into the source of ore material, this study presents new Re–Os and Pt–Os isotopic and highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, Re) abundance data for chromitite and native osmium from the Guli massif of ultramafic alkaline rocks and carbonatites located in the Maimecha–Kotui province, Polar Siberia. The study utilized a number of analytical techniques, including electron probe microanalysis (EPMA), negative thermal ionization mass spectrometry (N-TIMS), and high pressure asher digestion and isotope dilution inductively-coupled plasma mass-spectrometry (ID ICP-MS). The HSE concentrations in chromitite samples range from 191 to 866 ppb with a predominance of Ir-group platinum-group elements (PGE) (Os, Ir, and Ru) over Pt-group PGE (Rh, Pt, and Pd) and Re, which is consistent with the platinum-group mineral control (i.e., Os–Ir alloys and laurite, RuS2) within the chromitite. The Re–Os and Pt–Os isotope data indicate that the HSE budget of the chromitite and native osmium from the Guli massif was largely controlled by that of their mantle source, which evolved with long-term near-chondritic Re/Os and Pt/Os ratios; this source had time-integrated Re/Os and Pt/Os within the range of those for the majority of komatiites and abyssal peridotites worldwide. [ABSTRACT FROM AUTHOR]

Eastern Transbaikalia is a unique rare-metal province of Russia. Most of the studied deposits are associated with granitoid intrusions. Despite the high degree of knowledge of regional magmatism, a number of issues, related to both the belonging of specific massifs to magmatic complexes and the correlation of certain complexes within various structural-formation zones, remain. This paper compares the material composition and age of several petrotypical and parapetrotypical massifs, which are classified as Late Mesozoic complexes distributed within the Aginsk, Shilka, and Argun structural-formational zones of Eastern Transbaikalia. Based on the results of U–Pb dating, two stages of granitoid magmatism have been established: (1) the end of the Middle and the beginning of the Late Jurassic (163–156 Ma) and (2) the beginning of the Early Cretaceous (142 Ma). It is shown that the closely aged rocks of the Borshchovochnyi, Amudzhikan–Sretensk, and Shakhtama complexes have similar material characteristics, while the rocks of the Kukulbei complex (from three massifs) vary in composition. Elevated δ18O values (from +10.8 to +11.9‰) in the rocks of the Jurassic complexes indicate their formation mainly due to the melting of crustal material, and lower δ18O values (from +9.8 up to +10.3‰) in the Early Cretaceous granitoids suggest the contribution of a mantle source to their genesis. [ABSTRACT FROM AUTHOR]

The ice-rich core formation within the core of the lithalsa in the Sentsa River valley (West Buryatia) was studied. The concentrations of stable oxygen and hydrogen isotopes in the ice were determined, the plant residues in the enclosing deposits were aged. It was found that the lacustrine loams enclosing the ice body were accumulated about 4700-7000 years ago. The ice core of the lithalsa was characterized by δD values from 141.9 to-159.8‰, δO from-19.52 to-21‰, and d within 4.1-17.29‰. Small variations in the isotope composition of the ice-soil material within the lithalsa core point to its formation in an open system with water inflow from outside. The values of δO and δD were much closer to those for recent middle-winter and late-autumn atmospheric precipitation, as well as for riverine water, which pointed to a Holocene age of the ice. [ABSTRACT FROM AUTHOR]

Using the high-precision technique of MC-ICP mass spectrometry, the isotope composition of lead was studied for the first time in sulfides of different mineral associations at the Verninskoe deposit that belong to large gold deposits of the Lena Province. In 23 monofractions of sulfides (pyrite, arsenopyrite, galena, and sphalerite), the Pb-Pb data showed a pronounced heterogeneity of the isotope composition of ore lead (Pb/Pb = 18.21-18.69, Pb/Pb = 15.59-15.67, and Pb/Pb = 37.98-38.63) for the deposit as a whole. This heterogeneity is also seen to a lesser degree within individual samples. In this case, a correlation takes place between the isotope composition of ore Pb and the type of mineral association: the sulfides in earlier associations are characterized by lower contents of the Pb, Pb, and Pb radiogenic isotopes compared to the minerals of later parageneses. The comparison of Pb-Pb isotope characteristics of ore mineralization of the Verninskoe deposit to those of the Sukhoi Log deposit (the greatest in the Lena Province) testifies to the geochemical similarity of the sources of ore Pb involved in the formation of these deposits. The sources as such were terrigenous rocks of the Bodaibo synclinorium formed mainly as a result of the disintegration of Precambrian rocks of the Siberian craton. [ABSTRACT FROM AUTHOR]

The article discusses the strontium isotope signatures found in the Vendian Khorbusuonka group of the Olenek uplift river in the northeastern Siberian platform in Russia. It notes that the Vendian section of the Olenek uplift is one of the best reference successions for both regional and global correlation of Upper Precambrian deposits due to its unique paleontological characteristic and availability of geochronological dates. It states that no data are available for the chemostratigraphy of strontium isotope that prevents adequate assessment of age constraints for the Siberian hypostratotype. It also discusses the distribution of strontium isotope in carbonate rocks of the river aimed to assess their age to compare with other isotopic-chemostratigraphic methods.

The article offers information on the study based on the age and substance sources of the Ilmeno-Vishnevogorsky Alkaline Complex (IVC). It mentions that isochron method, a radiometric dating technique, was used for the dating of the main rock types of the IVC. It also adds that sources of substances for magmatic rocks and ores were established by using initial isotope characteristics of rocks and minerals of the IVC. It also adds that IVC has a source similar as that of ultra basic alkaline formation (UAC) source regarding the magma formation. It mentions of geochronological data that provides evidence that the IVC intruded rocks underwent significant transformations in the course of consolidation of the Ural Mountains.

The article focuses on the formation of rich datolite ores on the Dalnegorskoe skarn borosilicate deposit located in the center of the ore region, Russia. It states that this formation is interrupted by Altered basalts, alkaline basalts, and gabbro from dykes. It mentions that rocks of the ore zone has acquired a low oxygen isotope composition which resulted in the postmagnetic interaction with waters of meteoric origin. It also mentions that the Dal'negorskii ore region is known for its skarn and vein polymetallic deposits.

The article focuses on the zones of paleospreading and crustal extension in the Ural Mountains, Russia runs from north to south through western Russia. It states that the fragments of the sheeted dyke complex extends with breaks over 60 kilometers in the eastern framework of the Revda massif, Urals Region, Russia. It mentions that these dykes are made of fine grained gabbrodolerites and porphyritic dolerites with plagioclase and hornblende phenocrysts, as well as less common aphyric and fine porphyritic varieties.

The article presents study which investigates the isotope and age geochemistry of ore-hosting granodiorites of the Nyal'm-1 gold deposit at Kola Peninsula, Russia. It says that the Archean greenstone belts (GSBs) are localized in Paleoproterozoic volcanogenic-sedimentary complexes and are linked to the ore-metasomatic procedures in areas of shift deformations. It states that the investigation was done with the use of modern local isotope geochemical methods, along with the description of geological composition and structure of the volcanogenic-sedimentary complex of the GSB Kolmozero-Voron'ya (KV). Conclusion suggests that the age and genetic relationship of gold deposits enables the reconsideration of the concepts of the age of the gold formation.

The article presents a study on the composition, sources, and diamond potential of lamproite and kimberlite found in the Eastern Sayany area. It states that the Eastern Sayany area is a foreboding region for the discovery of original diamond deposits of various genetic types. It notes that several stages of lamproite and kimberlite intrusion are being identified within the Eastern Sayany area including the Mesoproterozoic, Neoproterozoic, and Middle Paleozoic. Moreover, the study speculates on the primary estimations of isotope geochemical specifics of deep sources of lamproitic, kimberlitic, and alkaline ultrabasic magmatism of the Siberian Platform region in Russia.

Metamorphic units of the Khavyven Highland that crop out in the northern portion of the Khavyven Uplift of the basement structures of the Central Kamchatka Trough are formed by rocks of the Khavyven Formation, which are metamorphosed in the green-schist facies. The formation comprises two strata: the lower part that consists of amphibole-micaceous ± garnet, epidote-micaceous ± garnet crystalline schists, and micaceous ± garnet quartzite schists has a total thickness of some 500 m, and the upper part, which is formed by epidote-amphibole and phengite-amphibole green schists and overlying epidote-amphibole-micaceous quartzites, with a visible thickness of some 750 m. The isotopic ratios of Sr, Nd, and Pb were determined in the examined rocks of the Khavyven Formation for the first time. The high 87Sr/86Sr and low 143Nd/144Nd ratios and the high K/La, Ba/Th, Th/Ta, and La/Nb ratios in combination with a deep Ta-Nb minimum indicate that the original volcanites of the crystalline schists of the lower rock mass had a subduction nature. The green schist of the upper rock mass, whose composition corresponds to that of spilitic basalts, have elevated 87Sr/86Sr and 143Nd/144Nd ratios, thus combining indications of depleted melts of the N-MORB and E-MORB types and those of subduction melts, which explains the deep Ta-Nb minimum and the low (La/Yb) N ratios. The isotopic signatures of lead in rocks of the lower and the upper strata are similar. The composition points of the crystalline schists and the green schists are located near the trend of isotopic evolution of lead in the depleted mantle, which indicates that the rocks are closely related to this mantle source. [ABSTRACT FROM AUTHOR]

The article reports on the study concerning the Paleoproterozoic layered Monchetundra Massifs of the Kola Region, Russia. It notes that the study of Monchetundra Massif, which is one of the objects promising with regard to economic Pt and Pd concentrations, made it possible to define the Kola platinum-bearing province. It uses the method of cumulative stratigraphy, which allows mafic and ultramafic rocks of the Monchetundra Massif to be subdivided into three zones wherein the lower zone composed of norites. It assumes that all lithologically similar igneous rocks of the complex in question were formed during several stages synchronously with the Monchegorsk Pluton and Fedorov-Pana Massif, taking into consideration all the new geological-geochronological data.

The article focuses on a study to investigate the petrogeochemical and isotope specifics of terrigenous rocks found in close paragenetic association with island arc magmatic complexes from the example of Neoproterozoic complexes of the Predivinsk Terrane of the Yenisei Ridge in Russia. The Western Block has metaplagiorhyolite–basalt and metaandesibasalt–andesite–dacite associations metamorphosed under the presence of the epidote amphibolite facies.

The article presents a study on the sulfates and sulfide in nitrogen hot springs of the Bauntov group of the Baikal Rift Zone (BRZ) in the Vitim River Basin in Russia. It says that physicochemical characteristics of nitrogen hot springs were examined using analytical techniques and precipitates for the assessment of isotopes were obtained by deposition with cadmium acetate, sulfate sulfur, and barium chloride. The results suggest that sulfide sulfur in the hot springs is depleted in heavy isotopes compared with that of sulfates and the chemical oxidation of sulfide sulfur under reduced environments at high Eh values is inconceivable. It adds that the influence of sulfate reduction in the improvement of sulfate sulfur in a heavy isotope is apparent.

The radioisotope compositions, structure, and behavior of “hot” particles under the natural conditions of the Yenisei River in the nearby influence zone of Krasnoyarsk mining and chemical combine were examined in this study. By the composition of gamma-radiating isotopes, all particles are divided into three groups: mono-isotopic, bi-isotopic and poly-isotopic. Mono-isotopic “hot” particles, containing only 60Co were discovered for the first time. Transuranium elements (241Am and 243Cm) were revealed in poly-isotopic particles. Investigation of poly-isotopic particles by means of a scan electron microscope showed that the presence of UO2 together with the lack of activation of 152Eu testifies to the reactor origin of this particle. Experiments showed that in natural conditions “hot” particles under the influence of filtrating water and moisture of pore solutions are gradually dissolved and radionuclides are repeatedly drawn into migration. [ABSTRACT FROM AUTHOR]