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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]

Large Arctic rivers are an important source of iron (Fe) to the Arctic Ocean, though seasonal variations in the terrestrial source and supply of Fe to the ocean are unknown. To constrain the seasonal variability, we present Fe concentrations and isotopic compositions (δ56Fe) for particulate (>0.22 µm) and colloidal (<0.22 µm–1 kDa) Fe from the Lena River, NE Russia. Samples were collected every month during winter baseflow (September 2012–March 2013) and every 2–3 days before, during and after river ice break-up (May 2015). Iron in particles have isotope ratios lower than crustal values during winter (e.g., δ56Fe Part = −0.37 ± 0.16‰), and crustal-like values during river ice break-up and spring flood (e.g., δ56Fe Part = 0.07 ± 0.08‰), indicating a change in the source of particulate Fe between winter and spring flood. Low isotope values are indicative of mineral dissolution, transport of reduced Fe in sub-oxic, ice-covered sub-permafrost groundwaters and near-quantitative precipitation of Fe as particles. Crustal-like isotopic compositions result from the increased supply of detrital particles from riverbank and soil erosion during river ice break-up and flooding. Iron colloids (<0.22 μm) have δ56Fe values that are comparable to or lower than crustal values during winter (e.g., δ56Fe Col = −0.08 ± 0.05‰) but similar to or higher than crustal values during spring flood (e.g., δ56Fe Col = +0.24 ± 0.11‰). Low δ56Fe ratios for colloidal Fe during winter are consistent with precipitation from isotopically light Fe(II) aq transported in sub-permafrost groundwaters. Higher colloidal δ56Fe ratios during the spring flood indicate that these colloids are supplied from surface soils, where Fe is fractionated via oxidation or organic carbon complexation, similar to during summer. Approximately half of the annual colloidal Fe flux occurs during spring flood while most of the remaining colloidal Fe is supplied during summer months. The total amount of colloidal Fe transported during winter was relatively low. The seasonal variation in colloidal Fe isotope values may be a useful tool to trace the source of colloidal Fe to the Arctic Ocean and monitor future changes in the sources and supply of Fe from the permafrost landscape to the Lena River basin. [ABSTRACT FROM AUTHOR]

The existing and recently acquired data on the isotope ages and compositions of volcanogenic Au–Ag deposits and occurrences of the Evensk group (Okhotsk–Chukotka volcanogenic belt, Northeast Russia) are summarized. The K–Ar isotope and Rb–Sr isochron ages of Au–Ag ores from the studied deposits and occurrences are 82.7 ± 3–77.5 ± 3 Ma and 84.1 ± 2–79.7 ± 5 Ma, respectively. Au–Ag mineralization was formed within ~5 Ma. Au–Ag mineralization typical of productive ore stages and practically unaffected by later thermal processes is characterized by low initial 87Sr/86Sr(0) = 0.7055–0.7059 ratios, which are close to the initial 87Sr/86Sr(0) ratios in wall-rock metasomatites (0.7033–0.7082) and unaltered host rocks (0.7045–0.7048), thus indicating a pronounced predominance of mantle Sr in the ores. The composition points of ore Pb on the 207Pb/204Pb–206Pb/204Pb evolution diagram are grouped in close proximity to the Pb isotope composition points in the depleted mantle with a trend towards the subduction-related volcanic rocks typical of the continental margin. A close genetic relationship between the ore and magmatic processes has been confirmed. It is assumed that this relationship is due to the functioning of a single mantle basaltic chamber, which served as a source of metal-bearing fluids and is probably the primary source of Au and Ag. [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 Paleoproterozoic metasedimentary rocks of the Zaonega Formation (Onega Basin, NW Russia) are important archives of inferred global environmental change following the initial oxygenation of the Earth's atmosphere and oceans. However, the geochemical signals preserved in these exceptionally organic-and pyrite-rich metasedimentary rocks and their environmental meaning remain contested. In particular, the Zaonega Formation's unusually high pyrite sulfur isotope ratios (δ34S) have been explained by either global or local forcings acting on sulfur cycling processes. We tested former interpretations of the Zaonega Formation's sedimentary pyrite record by integrating bulk and micro-scale δ34S analysis to discriminate the isotopic signatures of different generations of pyrite and determine the underlying mechanisms contributing to δ34S variability. We show that the prolonged genesis of pyrite occurred via multiple stages and included precipitation from early diagenetic fluids, organic matter pyritization, and late-stage alteration fluids. Our results demonstrate that early-stage pyrite typically carries more variable and lower δ34S values than late-stage pyrite. Although the early pyrite captures pore water S isotope signatures least evolved from the seawater, their contribution to the bulk δ34S results can be dwarfed by the greater volume of late-stage coarse pyrite. Consequently, determining the sequence of pyrite precipitation and δ34S characteristics of individual generations in any given sample are fundamental to interpreting bulk δ34S records. Our micro-scale results suggest that previous estimates based on bulk pyrite data (ca. 6 to 18‰) should not be related to the original seawater sulfate's isotopic composition. These results demonstrate that a thorough understanding of the geological context and mechanisms associated with S-cycling, and pyrite formation is necessary to interpret bulk δ34S records accurately. [ABSTRACT FROM AUTHOR]

The U-Pb isotope system and uranium isotope composition (235U/238U and 234U/238U) were studied in a number of samples from the vertical section of the uranium ore body at the Vershinnoe sandstone-type deposit, Vitim uranium ore district, Russia. These parameters were determined to broadly vary. Deviations of the 234U/238U ratio from the equilibrium value indicate that the uranium ore was not completely conserved during the postore stage, and uranium was determined to continue migrating at the deposit. Comparison of the U−Pb isotope age value and 234U/238U isotope ratio provides an insight into the migrate direction of uranium in the ore body. The broad variations (137.377–137.772) in the 238U/235U ratio over the vertical section of the ore body can be explained by the different settings of the samples relative to the ore deposition front and changes in the redox conditions when this front shifted. The fact that the δ238U and K234/238 values are correlated indicates that the transfer of the 234U isotope into the aqueous phase may have been coupled with isotope fractionation in the 238U−235U system during the postformation uranium migration within the orebody. [ABSTRACT FROM AUTHOR]

It has been suggested that the carbonated mantle reflected by Mg−Zn isotopic anomalies of Cenozoic intraplate basalts from East Asia coincides with the stagnant West Pacific slab in the mantle transition zone. However, the northern boundary of such carbonated domain beneath East Asia is uncertain. Late Mesozoic-Cenozoic intraplate basalts are widespread in far eastern Russia and thus provide an opportunity to examine this issue. Here we report major-trace element contents and Sr−Nd-−Mg−Zn isotopic compositions for 9 Late Mesozoic-Cenozoic basaltic samples from the Khanka Block and Sikhote-Alin accretionary complex. They are characterized by large variations in SiO2 contents (41 wt.% to 50 wt.%) and CaO/Al2O3 (0.50 to 0.97), enrichments of large-ion lithophile elements (LILE), positive Nb−Ta anomalies and strongly negative K, Pb, Zr, Hf, Ti, Y anomalies in primitive mantle-normalized trace element spider diagram. Furthermore, the rocks show good correlations of Ti/Ti* with Hf/Hf*, La/Yb, Fe/Mn and trace element contents (e. g., Nb). In addition, they have lighter Mg and heavier Zn isotope compositions than the BSE estimates, coupled with depleted Sr−Nd isotope compositions. These elemental and isotopic characteristics cannot be explained by alteration, magma differentiation or diffusion, but are consistent with the partial melting of carbonated peridotite. By and large, the Late Mesozoic-Cenozoic basalts from far eastern Russia bear very similar geochemical characteristics as those Na-series Cenozoic basalts from eastern China. The extended region of Mg−Zn isotopic anomalies is roughly coincident with the stagnant West Pacific slab beneath East Asia, and all of these alkali basalts can be generated from mantle sources hybridized by recycled Mg-carbonates from the Pacific slab stagnant in the mantle transition zone. We infer that (1) the carbonated big mantle wedge extends to the NE edge of the West Pacific slab and may have also appeared in the Late Mesozoic due to the effect of the Paleo-Pacific slab beneath this region, and (2) decarbonation of stagnant slabs in the mantle transition zone is a key mechanism for carbon outgassing from deep mantle to surface via intraplate alkali melts. [ABSTRACT FROM AUTHOR]

The first results of the study of the Re–Os isotope system of native gold from the orogenic Malo-Tarynskoe, Khangalas, and Bazovskoe deposits located in the central part of the Yana–Kolyma metallogenic belt are reported. The concentration of Re in the studied gold samples varies from 0.168 to 6.997 ppb, while the concentration of Os ranges from 0.068 to 1.443 ppb. The obtained data allowed us to calculate the isochrone age, which is consistent with the 40Ar–39Ar and K–Ar ages of sericite from these deposits within the error. The results indicate that the studied gold deposits were formed in the range of 147.8–137.1 Ma, synchronously with the Late Jurassic–Early Cretaceous orogenic processes in the Yana–Kolyma metallogenic belt and on the eastern margin of the Siberian Continent. The initial Os isotope ratios in the studied samples and fractions of gold from the Malo-Tarynskoe, Khangalas, and Bazovskoe deposits, (187Os/188Os)i = 0.1844–0.2475, suggest a significant role of a nonradiogenic component normally associated with mantle sources. [ABSTRACT FROM AUTHOR]

Anthropogenic Pb is widespread in the environment including remote places. However, its presence in Canadian Arctic seawater is thought to be negligible based on low dissolved Pb (dPb) concentrations and proxy data. Here, we measured dPb isotopes in Arctic seawater with very low dPb concentrations (average ∼5 pmol · kg−1 ) and show that anthropogenic Pb is pervasive and often dominant in the western Arctic Ocean. Pb isotopes further reveal that historic aerosol Pb from Europe and Russia (Eurasia) deposited to the Arctic during the 20th century, and subsequently remobilized, is a significant source of dPb, particularly in water layers with relatively higher dPb concentrations (up to 16 pmol · kg−1 ). The 20th century Eurasian Pb is present predominantly in the upper 1,000 m near the shelf but is also detected in older deep water (2,000 to 2,500 m). These findings highlight the importance of the remobilization of anthropogenic Pb associated with previously deposited aerosols, especially those that were emitted during the peak of Pb emissions in the 20th century. This remobilization might be further enhanced because of accelerated melting of permafrost and ice along with increased coastal erosion in the Arctic. Additionally, the detection of 20th century Eurasian Pb in deep water helps constrain ventilation ages. Overall, this study shows that Pb isotopes in Arctic seawater are useful as a gauge of changing particulate and contaminant sources, such as those resulting from increased remobilization (e.g., coastal erosion) and potentially also those associated with increased human activities (e.g., mining and shipping). [ABSTRACT FROM AUTHOR]

Possible strategies of the development of low-energy nuclear physics in Russian Federation on the basis of the DERICA (Dubna Electron–Rare Isotope Collider fAcility) project is examined. DERICA is a multiuser multipurpose facility for the production and study of radioactive isotopes (RI). In the research program of DERICA, emphasis is placed on studying RI in collector rings, but a stage-by-stage implementation of the program of DERICA would make it possible to address a wide range of fundamental problems at each stage of its development at the cutting-edge level. The ambitious goal of creating an electron–radioactive ion collider for studying basic properties of RI in electron–ion scattering is proposed for the final stage of development of DERICA. [ABSTRACT FROM AUTHOR]

Details of the Early-Middle Frasnian boundary interval of the Pymvashor River section (Timan-Pechora Basin, Cis-Urals, in the far north of European Russia) are revealed by biostratigraphically constrained carbonate (d13Ccarb) and organic carbon (d13Corg) stable data. The studied interval corresponds to the lower part of the Domanik Formation, which consists of interbedded limestone and shale beds. Organic-rich black shale that lacks bioturbation and benthic organisms indicates an oxygen-depleted depositional environment. Detection of isorenieratene derivatives in organic matter indicates that anoxia was present in the photic zone during deposition. The Pymvashor River section contains d13Ccarb and d13Corg isotope records related to the Early-Middle Frasnian isotope Event. The similarity between the Cis-Uralian (this study) and the Chinese d13Ccarb and d13Corg oscillations, including the twostep pattern of the recorded major positive excursions, suggests a robust correlation of the Late Devonian Early-Middle Frasnian isotope Event and minor intra-event excursions. Magnitude of variations and values of d13Corg and d13Ccarb in the punctata Zone in the Pymvashor River section are minor than those observed in the North American, Polish, and Chinese successions. Such difference may reflect specific variation of the local environments. [ABSTRACT FROM AUTHOR]

Chromium isotope and chemical compositions in runoff from two felsic rock catchments, the Lysina (LYS; Czech Republic) and the Neglinka (NEG; northwest Russia), were studied. Three types of water were identified: Na-Ca-SO4 type for the LYS, Mg-Ca-Cl-HCO3 type for the NEG downstream, and Mg-Ca-Cl to Mg-Ca-HCO3 type for the NEG upstream. The Cr (III) liberated during soil/bedrock weathering oxidized to Cr (VI), which was the main dissolved Cr species in both catchments. Variations in δ53Cr values for LYS runoff (–0.07‰ to +0.37‰) reflected a sole Cr source, seasonality of weathering and hydrologically controlled leaching/export processes. In the NEG catchment, back-reduction of Cr (VI) to Cr (III) during riverine transport resulted in a decrease in Cr concentrations (to 10–30%) and in an increase of δ53Cr values (+0.09 to +0.42‰ for the upstream to +0.72 to +1.73‰ for the downstream). Groundwater discharge could have influenced the chemical composition of the downstream NEG runoff to some extent. [ABSTRACT FROM AUTHOR]

The largest CO2-rich mineral water resource in the Sikhote-Alin ridge of Eastern Russia at Gornovodnoe village was studied. The high-pCO2 groundwaters are cold (5.8–10 °C) with pH 5.9–6.5, TDS varied from 1.2 to 2.7 g/l and belong to Ca–Mg (Ca–Na)–HCO3 type. New data on geology, mineralogy, hydrogeology and hydrogeochemistry, in conjunction with isotope data of water and gas phases, have provided a much better understanding of the origin of this distinctive groundwater. It was found that this water is of meteoric origin, but its unusual chemical composition is controlled by interactions of CO2-rich groundwater and the aquifer materials. The dissolved CO2 gas makes the water slightly acidic (at about pH 6.2) which increased the leaching of many trace elements from host volcanic rocks typically considered immobile at these pH values. 3He/4He ratios and δ13C indicate that mantle degassing is important as a source of deep exogenic fluids. The cold CO2-rich groundwater of the Eastern Sikhote-Alin ridge is the result of interactions between fresh groundwater of meteoric origin, mantle gases and the host volcanic rocks. It thus highlights connectivity between deep and shallow fluids along with deep fractures related to ancient terrane boundaries. [ABSTRACT FROM AUTHOR]

Lake El'gygytgyn in far northeastern Russia provides one of the few records that can improve understanding of terrestrial responses to climatic changes during the Early to Middle Pleistocene transition (EMPT; 1400–400 ka). Palynological data from MIS 38‐31 (~1260 to 1060 ka) help clarify the complex nature of that transition. In contrast to the evergreen conifer forest of the MIS 31 'super' interglaciation, Larix‐Betula‐Alnus forest with shrub tundra characterized MIS 37 and MIS 35. The Larix forest‐tundra of MIS 33 represents an even cooler interglaciation. The landscapes of MIS 38, MIS 36 and early MIS 34 were a tundra mosaic with areas of Larix‐forest tundra. Although marine records suggest that MIS 38 and MIS 36 were exceptionally harsh glaciations, the decrease in woody taxa (particularly Alnus and Pinus) indicate the coolest conditions at El'gygytgyn occurred during MIS 32 and late MIS 34. When combined with other palynological data from El'gygytgyn, the EMPT portion of the record indicates that Betula was important in the vegetation during both cool and warm periods prior to MIS 24. Following the build‐up of global ice volumes ~900 ka, the taxon was characteristic of warm intervals only, marking the establishment of the herb‐dominated tundra, which typifies the remainder of the Pleistocene glaciations. The more complex successional patterns in post‐900 ka vegetation suggest greater climate variability as ice volume increased. Pinus pumila became a significant component of interglacial vegetation following the shift from a 41 ka to a quasi‐100 ka orbital cycle, indicating an increase in snow cover and a lessening of aridification, at least in this part of the Arctic. [ABSTRACT FROM AUTHOR]

In this paper, new main and trace elements and isotopic data are presented for 14 coarse-grained eclogite xenoliths from the V. Grib kimberlite pipe in the central part of the Arkhangelsk Diamondiferous Province. Based on reconstructed whole rock MgO content, this suite is divided into high-MgO and low-MgO varieties. Eclogitic groups have a similar range of variations in the trace element compositions of garnet, clinopyroxene and reconstructed whole rock. All eclogites show positive Eu anomalies in garnet and Sr anomalies in the whole rock. The negative correlation between the Mg#, Sr/Lu ratio and HREE in a whole rock points to upper and lower oceanic crustal rocks as a protolith for eclogites with high and low whole rock HREEs, respectively. Low-MgO eclogites with higher whole rock HREEs have the basaltic upper oceanic crustal protolith, whereas the protoliths of eclogites with lower whole rock HREEs could be of gabbroic composition from the lower oceanic crust. High-MgO eclogites could represent MgO-rich portions of oceanic crustal rocks: picritic/MgO basalt portions in the upper oceanic crust and troctolite portions in the lower oceanic crust. The Sr and Nd isotope compositions suggest a complex history of eclogites during their residence in the lithospheric mantle. Similarities in the Nd isotope compositions and two-point Sm-Nd isochron ages are evidence for re-equilibration of the Sm-Nd isotope system between the eclogite garnet and clinopyroxene via a pre-kimberlite thermal event at 396 ± 24 Ma. The subset of clinopyroxenes from four eclogites has a Sr isotope composition that plots on the isochron at an age of 2.84 Ga, which reflects the time of the subduction event and emplacement into the lithosphere and corresponds to the time of the Belomorian Eclogite Province of Baltic Shield formation. [ABSTRACT FROM AUTHOR]

The association of organic-walled microfossils of the Kaltasy Formation, which includes morphologically complex large forms, is considered on the basis of previous and new materials. In general, the Kaltasy microbiota is similar to many associations of the Neoproterozoic (Late Riphean and Vendian) microfossils and, originally, was erroneously interpreted as Late Riphean, in spite of missing Late Riphean index taxa and geological evidence of its Early Riphean age. The Early Riphean age of the formation was supported by results of Re–Os, U–Pb, and other modern methods of isotope geochronology, whereas the low 87Sr/86Sr ratios and almost invariant δ13C values of its rocks are comparable with isotopic characteristics of the Mesoproterozoic sequences of >1300 Ma. The application of geochemical methods using high-reagent Fe (FeHR) and C and S isotopes has showed that relatively deep rocks of the Arlan Subformation of the Kaltasy Formation accumulated under aerobic oxidation conditions (ratio FeHR/FeT < 0.38). This contradicts a common concept of the presence of an anoxic ocean in the Mezoproterozoic, but explains the presence of morphologically complex large eukaryotic forms of microbiota, which were abundant in Neoproterozoic oxygenic basins. [ABSTRACT FROM AUTHOR]

The behavior of actinides (U, Am, Pu) in the course of combustion of radioactive graphite in steam was studied by thermodynamic modeling. Thermodynamic modeling was performed using TERRA program in the temperature interval from 373 to 3273 K to determine the possible composition of volatile actinide species formed in the course of graphite utilization by heating in steam. The modeling shows that the actinides at high temperatures are present in the following forms: U, as UO and UO vapors and as UO and UO ions; Am, as Am vapor; and Pu, as PuO and PuO vapors and as ionized PuO. The main reactions within separate phases and at the interface were revealed, and their equilibrium constants were determined. [ABSTRACT FROM AUTHOR]

Calcareous tufa deposits have been discovered in the Chibitka River valley near Lake Cheybek-Kohl, at the junction of the Kurai and Teletsk-Kurai large active faults in the southeastern Gorny Altai, Russia, at an altitude of 1800–2000 m. Fossil tufa is composed of calcite and cements Holocene grey colluvium and glacial till deposited by the Late Glacial Chibitka Glacier. Current tufa precipitation has been observed from a low-flow spring with cold (10 °C) HCO 3 -SO 4 –Ca-Mg water, рН = 6.86. The stable isotope composition of spring water is − 5.8‰ VPDB δ 13 C of dissolved inorganic carbon and − 14.5‰ VSMOW δ 18 O. Modern tufa consists of thin laminated Mg-calcite and Sr-aragonite crusts, with abundant algae and biofilms on their surfaces. Both modern and fossil tufas are depleted in REE (a total of 0.40–16.4 ppm and 0.40–3.80 ppm, respectively) and share similar PAAS-normalised REE + Y spectra with HREE enrichment and slight progressive LREE depletion. The modern tufas show positive δ 13 C values of 0.1‰ to 0.9‰ VPDB while the fossil ones have an isotopically lighter composition of δ 13 C = − 4.1‰ to − 1.9‰ VPDB; the δ 18 O range is very narrow (− 13.0 to − 13.8‰ VPDB). Both stable isotope and trace-element signatures (including REE patterns) of the tufas indicate precipitation from cold groundwaters subjected to prolonged interaction with a carbonate aquifer (the Baratal Group of limestone and dolostone) in a cold continental climate similar to the present conditions. Tufa deposition in the Lake Cheybek-Kohl area began with the onset of post-Late Glacial global warming and permafrost degradation. Unlike the fossil tufa formation, current precipitation of freshwater carbonates has been microbially mediated. The discovered tufa deposits provide new palaeoclimatic and active tectonic proxies in the southeastern Gorny Altai. [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]

The evolution of opinions about the isotope age of the general stratigraphic subdivisions of the Upper Proterozoic in Russia (Lower, Middle, Upper Riphean and Vendian) during the second half of the 20th century and the beginning of the 21st century is considered, and the current data on the age of these subdivisions are analyzed in detail. It is shown that the isotope age of the lower boundaries of the Lower, Middle, and Upper Riphean and Vendian should be estimated at 1750 ± 50, 1400, 1030, and 640 ± 5 Ma, respectively. The role of the historical-geological criteria in the substantiation of these boundaries is studied. [ABSTRACT FROM AUTHOR]

The article presents a study that determines the isotope-geochemical data in the ferruginous mineral waters at the Marcial waters resort in Karelia, Russia. It offers brief overview of the method of the study which uses systematic measurement of the isotope composition to examine the conditions of formation of the mineral waters. It outlines the result of the study which indicates that the isotope composition and tracers of the Marcial Waters show an elevated fraction of infiltration feed.

This report presents original data on the hydrochemical, isotope, and microbiological composition of nitric thermal waters of the Goryachii Klyuch spring (Primorskii Krai). The first-performed year-round surveys of the conditions of the spring water and the environment have shown that the ground waters heated over 30°C in fractured siliceous Upper-Permian rocks suffered no significant seasonal variations in their temperature and discharge during a year, and the slight seasonal variations in the chemical composition of the waters were caused by the interactions in the water-rock system. The isotope studies (δO, δH, and H) have shown that the thermal waters were of atmospheric genesis and with a long-term circulation period of >50 years. The processes of the transition of elements to the solution were decelerated at the absence of soluble rocks and aggressive gases, which caused the low mineralization of the waters. The water temperature was determined by the depth of their circulation amounting to 1-2 km. It was found that the processes of the carbon and nitrogen cycles involving microorganisms were the most intense in the thermal waters. [ABSTRACT FROM AUTHOR]

Marine Isotope Stage 11 has been proposed as an analogue for the present interglacial interval; yet, terrestrial climate records from both this region and time interval are rare. The sediments deposited at Lake El'gygytgyn (67°30′N, 172°5′E) in Far East Russia contain a 3·56 Ma record of climate variability. This study presents a high-resolution record of sediment colour change from Marine Isotope Stage 8 to 12 ( ca 275 to 475 ka) and demonstrates the link between lake catchment processes and climate variability. The hue colour parameter, calculated from data collected via colour reflectance spectroscopy in the visible spectrum (380 to 720 nm), exhibits correspondence with global climate records. Determining the source of sediment colour changes was achieved through detailed mineralogical and sedimentological methods, and linked to colour changes through a series of colour sensitivity tests. Mineralogical data, measured by X-ray diffraction, reveal fluctuations in concentrations of clay minerals corresponding to colour changes. Further analyses of the clay mineral assemblages show no change in relative clay mineral abundances, yet demonstrate a lake catchment dominated by physical weathering processes. Using measured mineral abundances, reconstructions of sediment colour based on colour reflectance mineral standards link mineral and clay mineral content to overall sediment colour. Colour sensitivity tests demonstrate the ability of iron oxide minerals to stain sediments red. Additionally, colour sensitivity to organic matter content was tested, suggesting that organic content drives variability in the red portion of the spectrum and darkens the overall colour signal. Sediment colour is then ultimately linked to physical weathering of bedrock minerals, with small amounts of chemical weathering producing iron oxides during wet intervals. Fluctuations in the sediment colour reveal a high-resolution record of wet/dry cycles, and provide new information about wet periods for the Russian Arctic region not yet understood from other lake proxy records. [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]

[Display omitted] • The authors have recognized four species of intrusion-hosted deposits: gold-telluride, gold-tetradymite, gold-stibnite, and gold-bismuth-sulfosalt. • Intrusion-hosted gold deposits were formed during the two orogenic stages of the East Sayan geodynamic evolution: Neoproterozoic (860–850 Ma) and Early Paleozoic (458–439 Ma). • The different gold-associated mineral assemblages are interpreted by geochemically different parental granitoid intrusions. Our paper reviews a series of relatively low-grade gold deposits and prospects hosted by granitoid intrusions within the southeastern East Sayan in the Altaid Belt (northern Central Asian Orogenic Belt, Russia). The studied deposits/prospects are characterized by the presence of Te-, Sb- and Bi-bearing minerals. However, they differ in their main gold-associated mineral assemblages, which permits to distinguishing four mineralization assemblages: 1) gold-telluride; 2) gold-tetradymite; 3) gold-stibnite; and 4) gold-bismuth sulfosalt. The gold-telluride mineralization (1) is represented by the Tainskoye deposit, and the Khoringolskoye and Sagangolskoye prospects which are defined by paragenesis of native gold with Au-Ag-Bi-Pb-Ni tellurides, such as hessite, petzite, altaite, wehrlite, calaverite, melonite, altaite, and tellurobismuthite. The gold-tetradymite mineralization (2) which is represented by the Konevinskoye deposit, is hosted by the Saylag granitoid pluton, and contains tetradymite as one of the principal minerals associated with native gold. The gold-stibnite mineralization (3), represented by the Tumannoye prospect, is also hosted in a granitoid complex consisting of granodiorite and leucogranite. The gold-bismuth-sulfosalt mineralization (4) is documented at the Pogranichnoye prospect, where native gold is associated with the bismuth-bearing minerals: bismuthinite, galeno-bismuthite, lillianite, and native bismuth. Estimated δ18O values of ore-forming fluids from intrusion-hosted deposits range from 5.7 to 7.4‰, indicative of a magmatic origin; δ34S values of sulfides vary from −4.2 to 4.5‰, which corresponds to magmatic sulfur. The geological setting, element geochemistry of host granitoids, stable isotope ratios, and mineralogy of the studied deposits are consistent with a magmatic origin of the mineralizing fluids. The studied deposits are spatially associated with either Neoproterozoic or Early Paleozoic granitoids, belonging to the two main orogenic stages of the East Sayan geodynamic evolution. At ∼850 Ma, during the Neoproterozoic stage, deposits with dominant gold-telluride assemblages, formed in association with granitoids characterized by geochemical features of island arc granites. During 458–439 Ma, in the Early Paleozoic stage, gold-tetradymite, gold-stibnite, gold-telluride and gold-bismuth-sulfosalt assemblages were formed that are spatially associated with orogenic granites with different geochemical compositions. Most gold-bearing mineral assemblages are intersected by post-mineral Late Paleozoic dykes. The origin of these different gold-sulfide-telluride assemblages is explained with their genetic association with granitoid intrusions of different ages and compositions. [ABSTRACT FROM AUTHOR]

Artificial radionuclides, such as iodine-131 (I), cesium-134 (Cs), and cesium-137 (Cs), as well as natural isotopes of beryllium-7 (Be) and potassium-40 (K) have been registered in atmospheric aerosols over Vladivostok selected from 11 March to 17 June 2011. Additionally, Cs and Cs were detected in atmospheric aerosols over Tomsk selected from 16 March to 17 June 2011. Artificial radionuclides were also discovered in atmospheric wet depositions sampled in Vladivostok from 3 to 17 May 2011. Moreover, these radionuclides have been registered in atmospheric aerosols over the sea surface of the Sea of Japan selected from 3 to 31 May 2011 during an expedition of the 'Nadezhda' sailing ship. From 18 March to 15 April, an increase in concentrations of atmospheric aerosols over Vladivostok from 108.8 to 321.5 μg/m has been registered. It was accompanied by increased activity concentrations of Cs, Cs, and the I. During the period from 18 March to 15 April, activity concentrations of Cs and Cs in atmospheric aerosols increased 100 times compared with the minimum detectable concentration (MDC) level and peaked in the weekly sample gathered from 8 to 15 April (145.0 and 105.3 μBq/m, respectively). Variability of concentrations of natural isotopes of Be and K was not greater than 1 order of magnitude throughout the sampling period. Maximal values of Cs and Cs concentrations (1,281.5 ± 141 and 384.4 ± 42.3 μBq/m, respectively) in Tomsk were reached in samples taken from 1 to 2 April. For the atmospheric aerosol samples from the Sea of Japan, the largest concentration of I (392.3 ± 215.7 μBq/m) was detected from 13 to 19 May, while all other samples had much lower concentration values. Synoptic analysis of back trajectories movement of air masses showed that the radioactive cloud came to Vladivostok from the regions of Siberia and northeastern part of China. Synoptic analysis for Tomsk showed that during the period of maximal activity concentrations (1-9 April), air masses were arriving from the European part of Russia and north of Kazakhstan. [ABSTRACT FROM AUTHOR]

Abstract: We present a review of reactor and accelerator centers in Russia that produce medical isotopes, the majority of which are exported. In the near future, we anticipate increased isotope production for use in nuclear medicine in Russia. The existing linear accelerator at the Institute for Nuclear Research (Moscow–Troitsk) and several prospective installations are considered to be particularly capable of providing mass production of radionuclides that can substitute, to a certain extent, for the traditional medical isotopes. [Copyright &y& Elsevier]

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.

Abstract: Detailed geochemical, isotope, and geochronological studies were carried out for the granitoids of the Chuya and Kutima complexes in the Baikal marginal salient of the Siberian craton basement. The obtained results indicate that the granitoids of both complexes are confined to the same tectonic structure (Akitkan fold belt) and are of similar absolute age. U–Pb zircon dating of the Kutima granites yielded an age of 2019±16 Ma, which nearly coincides with the age of 2020±12 Ma obtained earlier for the granitoids of the Chuya complex. Despite the close ages, the granitoids of these complexes differ considerably in geochemical characteristics. The granitoids of the Chuya complex correspond in composition to calcic and calc-alkalic peraluminous trondhjemites, and the granites of the Kutima complex, to calc-alkalic and alkali-calcic peraluminous granites. The granites of the Chuya complex are similar to rocks of the tonalite–trondhjemite–granodiorite (TTG) series and are close in CaO, Sr, and Ba contents to I-type granites. The granites of the Kutima complex are similar in contents of major oxides to oxidized A-type granites. Study of the Nd isotope composition of the Chuya and Kutima granitoids showed their close positive values of εNd(T) (+1.9 to +3.5), which indicates that both rocks formed from sources with a short crustal history. Based on petrogeochemical data, it has been established that the Chuya granitoids might have been formed through the melting of a metabasitic source, whereas the Kutima granites, through the melting of a crustal source of quartz–feldspathic composition. Estimation of the PT-conditions of granitoid melt crystallization shows that the Chuya granitoids formed at 735–776 °C (zircon saturation temperature) and >10 kbar and the Kutima granites, at 819–920 °C and >10 kbar. It is assumed that the granitoids of both complexes formed in thickened continental crust within an accretionary orogen. [Copyright &y& Elsevier]

A systematic study of Pb isotope composition was carried out for Elbrus Volcano, one of the Europe's largest volcanoes, using high-precision method of multi-collector inductively coupled plasma mass spectrometry. The measurement error of Pb isotope ratios was estimated from the results of replicate analyses of international BCR-1 and AGV-1 standards as ±0.03% (±2SD). The study of a representative collection showed that dacites of all three phases of the Elbrus eruptive activity are characterized by relatively small-scale variations of Pb isotope composition: Pb/Pb 18.621-18.670, Pb/Pb 15.636-15.659, and Pb/Pb 38.762-38.845. New Pb isotope geochemical characteristics in combination with existing Sr-Nd data indicate that the parental magmas of Elbrus are of mixed mantle-crust origin. They were formed by interaction of mantle-derived melts with continental crust of the Greater Caucasus during continental collision between the Eurasian, Arabian, Turkish, and Iranian plates. [ABSTRACT FROM AUTHOR]

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.

Abstract: The paper addresses genetic relationship between volcanic rocks and ore-bearing intrusions of the Noril''sk area, Siberian Trap Province. Mg-rich rocks were found inside layered the Mikchangdinsky and Ikensky flows at the highest level of the vertical section of a tuff-lava pile in the Nadezhdinsky Formation in the eastern part of the Noril''sk area. The high La/Sm, Th/U ratios, depletion in Cu, highly radiogenic Sr and unradiogenic Nd isotope compositions suggest their affiliation with the Lower Nadezhdinsky Formation and distinguish them from the Sunduksky layered flow, which has similar internal structure but belongs to the Tuklonsky Formation. The composition of layered Mg-rich basalt flow (the Mikchangdinsky flow) indicates that these rocks likely represent previously unknown parental melt of Nadezhdinsky lavas which are thought to play a crucial role in the genesis of ore mineralisation. Compositionally this melt was significantly different from the parental melt, which formed lavas of the Tuklonsky Formation and this precludes their direct genetic relationship. Olivine composition of the Mikchangdinsky flow indicates rapid depletion of melt by Ni and Cu suggesting early precipitation and fractionation of sulphide melt. Chemical composition and Sr and Nd isotope compositions of rocks from the Mikchangdinsky flow are similar to the Low Talnakh intrusion, while composition of olivine and coexisting spinels manifest significant differences. The compositional differences between the olivine (contents Mn and V) and coexisting spinel (Fe2+/Fe3+ ratios) from the picrite gabbro-dolerites of the Low Talnakh intrusion and picrite of the Mikchangdinsky flow suggest that they may have crystallised from magma of similar composition but at different oxygen fugacity (intrusions being unusually oxidised). The substantial differences in contents of Ca, HREE and Y in olivines from these objects, however, leave open the question of genetic relationship between Nadezhdinsky parental melt and the Low Talnakh intrusion. Although some rocks of the Nadezhdinsky Formation contain unusually low concentrations of chalcophile elements, their role in the ore-forming processes of the Noril''sk district still remains largely uncertain. [Copyright &y& Elsevier]

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.

New data on the Hf, Pb, and Nd isotopes of the mafic rocks of various ages from Kunashir Island were used to address the nature of the sub-arc mantle of the southern segment of the Kuril island arc. At least since Late Cenozoic, its isotopic characteristics have been the MORB-type mantle of the Indian Ocean. Its boundary with the mantle reservoir of the Pacific MORB-type coincided probably with the Kuril-Kamchatka Trench. [ABSTRACT FROM AUTHOR]

This paper is dedicated to the isotope-geochronological study of the rocks that compose two large intrusions and a separate group of minor intrusions in the western part of the Kavalerovo ore district. In most publications, these rocks are considered as monzonitic or trachyandesite-monzonitic association. On the basis of the amphibole and biotite K-Ar ages and the Rb-Sr whole-rock and mineral datings, the studied association was formed within the interval of 113-98 Ma. A wider interval of 115-95 Ma was obtained with allowance for other isotope data, including those on the rocks of the volcanic facies. This is consistent with the concepts that the studied association belongs to a single magmatic complex. No significant and systematic age differences have been established between the compositionally similar rocks from the different massifs. In compliance with the scheme of the geodynamic evolution of the region, the chambers of latitic melts of the volcanic and most intrusive rocks of the complex were formed prior to the initiation of the Sikhote-Alin subduction volcanic belt. The initial stage of the formation of the latter is presumably constrained by the data on the biotite from the quartz diorites from the Uglovaya VTS (90 Ma), which is located in the central part of the region, and on the late amphibole from the monzonitoids of its western part (91-92 Ma). The geochemical differences between rocks from the different intrusive bodies could be caused by the specifics of the melt evolution in the intermediate or crystallization chambers. [ABSTRACT FROM AUTHOR]

Abstract: Reconstructing Quaternary glacial and environmental changes in the vast, high-northern latitudes of Siberia is essential for a better understanding of global past climate variability and its potential solar forcings. Two sediment outcrops in the Dyanushka Valley in the southwestern foreland of the Verkhoyansk Mountains, northeast Siberia, were investigated using a multi-proxy approach (lithostratigraphy, geochemistry, palynology, and radiocarbon and IRSL dating). Three piedmont glaciations reached the outcrop sites. The glacial advances are dated to >140, ∼119–92 and ∼78–53 ka and thus, within dating uncertainties, correspond to obliquity minima during marine isotope stages (MIS) 6, 5d, and 4. This chronology corroborates and refines previous studies that have documented the successively more restricted glacial extents in Siberia during the course of the last glacial cycle. The observed glaciation pattern is out of phase with global ice volume estimates and probably indicates a strong aridisation trend. Additionally, the results show that the geochemical and mineralogical composition of the sediments contains information about provenance. Sediments originating from the Verkhoyansk Mountains are generally enriched in TiO2, MgO, P2O5, Fe2O3, Cr, illite, and chlorite, whereas sediments derived from the Lena River contain more expandable clay minerals, Ba, Sr. Alkane patterns as biomarker proxies turn out to be particularly valuable where poor preservation of pollen is an issue, and, generally speaking, vegetation reconstruction helps distinguishing between ‘warm versus cold mode’ sediments. [Copyright &y& Elsevier]

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.

The use of Cambrian clay from Leningrad oblast for cementing radioactive sludge deposits from natural water reservoirs is discussed. The addition of Cambrian clay impedes separation of the mixture of sludge with cement and decreases the leaching of 137Cs from the solidified products at least five-fold. [ABSTRACT FROM AUTHOR]

Detailed spectroscopic information of excited nuclear states in deformed transfermium nuclei is scarce. Most of the information available today has been obtained from investigations of fine-structure α-decay. Although α decay gives access to hindrance factors and lifetimes which are strongly correlated to shell/subshell closures and the presence of isomers, only the combined use of γ and conversion electron spectroscopy allows the precise determination of excitation energy, spin and parity of nuclear levels. In the years 2004–2009 using the GABRIELA set-up [Hauschild et al, Nucl. Instrum. Methods A560, 388 (2006)] at the focal plane of VASSILISSA separator [Malyshev et al, Nucl. Instrum. Methods A440, 86 (2000); A516, 529 (2004)] experiments with the aim of γ and electron spectroscopy of the isotopes from Fm to Lr, formed by complete fusion reactions with accelerated heavy ions were performed. In the following, the preliminary results of decay studies using α-γ and α-β coincidences at the focal plane of the VASSILISSA recoil separator are presented. Accumulated experience allowed us to perform ion optical calculations and to design the new experimental set-up, which will collect the base and best parameters of the existing separators and complex detector systems used at the focal planes of these installations. In the near future it is planned to study neutron-rich isotopes of the Rf-Sg in the ‘hot’ fusion reactions with Ne incident projectiles and Pu, Am and Cm targets. [ABSTRACT FROM AUTHOR]

Abstract: New structural, petrological, chemical, isotope, and paleomagnetic data have provided clues to the Late Riphean–Paleozoic history of the Uda–Vitim island arc system (UVIAS) in the Transbaikalian sector of the Paleoasian ocean, as part of the Transbaikalian zone of Paleozoids. The island arc system consists of three units corresponding to main evolution stages: (i) Upper Riphean (Late Baikalian), (ii) Vendian–Lower Paleozoic (Caledonian), and (iii) Middle–Upper Paleozoic (Hercynian). The earliest stage produced the base of the system composed of Late Riphean ophiolite (971–892 Ma, U-Pb) and volcanic (837–789 Ma, U-Pb) and sedimentary rocks (hemipelagic siliceous sediments and dolerite sills) which represent the Barguzin–Vitim oceanic basin and the Kelyana island arc. The main event of the second stage was the formation of the large UVIAS structure (over 150,000 km2) which comprised the Transbaikalian oceanic basin, the forearc and backarc basins, and the volcanic arc itself, and consisted of many volcanic-tectonic units exceeding 100 km2 in area (Eravna, Oldynda, Abaga, etc.). Lithology, stratigraphy, major–element compositions, and isotope ages of Vendian–Cambrian volcanic rocks and associated sediments indicate strong differentiation of calc-alkaline series and the origin of the island arc system upon oceanic crust, in a setting similar to that of the today’s Kuriles–Kamchatka island arc system. The Middle–Upper Paleozoic stage completed the long UVIAS history and left its imprint in sedimentary and volcanic rocks in superposed trough basins. The rocks were studied in terms of their biostratigraphic and isotope age constraints, as well as major- and trace-element compositions, and were interpreted as products of weathering and tectonic-magmatic rework of the UVIAS units. [Copyright &y& Elsevier]

The two world’s largest complexes of highly alkaline nepheline syenites and related rare metal loparite and eudialyte deposits, the Khibina and Lovozero massifs, occur in the central part of the Kola Peninsula. We measured for the first time in situ the trace element concentrations and the Sr, Nd and Hf isotope ratios by LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometer) in loparite, eudialyte an in some other pegmatitic minerals. The results are in aggreement with the whole rock Sr and Nd isotope which suggests the formation of these superlarge rare metal deposits in a magmatic closed system. The initial Hf, Sr, Nd isotope ratios are similar to the isotopic signatures of OIB indicating depleted mantle as a source. This leads to the suggestion that the origin of these gigantic alkaline intrusions is connected to a deep seated mantle source—possibly to a lower mantle plume. The required combination of a depleted mantle and high rare metal enrichment in the source can be explained by the input of incompatible elements by metasomatising melts/fluids into the zones of alkaline magma generation shortly before the partial melting event (to avoid ingrowth of radiogenic isotopes). The minerals belovite and pyrochlore from the pegmatites are abnormally high in 87Sr /86Sr ratios. This may be explained by closed system isotope evolution as a result of a significant increase in Rb/Sr during the evolution of the peralkaline magma. [ABSTRACT FROM AUTHOR]

Using a theoretical model and mass isotopic balance, biogas (methane and CO2) released from buried products at their microbial degradation was analysed in the landfill of municipal and non-toxic industrial solid organic waste near Kaluga city, Russia. The landfill contains about 1.34×106 tons of waste buried using a 'sandwich technique' (successive application of sand-clay and waste layers). The δ13C values of biogenic methane with respect to CO2 were-56.8 (±2.5) ‰, whereas the δ13C of CO2 peaked at+9.12‰ (+1.4±2.3‰ on average), reflecting a virtual fractionation of carbon isotopes in the course of bacterial CO2 reduction at the landfill body. After passing through the aerated soil layers, methane was partially oxidised and characterised by δ13C in the range of-50.6 to-38.2‰, evidencing enrichment in 13C, while the released carbon dioxide had δ13C of-23.3 to-4.04‰, respectively. On the mass isotopic balance for the δ13C values, the methane production in the landfill anaerobic zone and the methane emitted through the aerated landfill surface to the atmosphere, the portion of methane oxidised by methanotrophic bacteria was calculated to be from 10 to 40% (averaged about 25%). According to the theoretical estimation and field measurements, the annual rate of methane production in the landfill reached about 2.9(±1.4)×109 g C CH4 yr-1 or 5.3(±2.6)×106 m3 CH4 yr-1. The average rates of methane production in the landfill and methane emission from landfill to the atmosphere are estimated as about 53 (±26) g C CH4 m-2 d-1 (or 4 (±2) mol CH4 m-2 d-1) and 33 (±12) g C CH4 m-2 d-1 (or 2.7 (±1) mol CH4 m-2 d-1), respectively. The calculated part of methane consumed by methanotrophic bacteria in the aerated part of the landfill was 13(±7) g C CH4 m-2 d-1 (or 1.1(±0.6) mol CH4 m-2 d-1) on average. [ABSTRACT FROM AUTHOR]

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.

Abstract: The δ37Cl values of volcanic fumarole gases and bubbling springs were measured from the Central American and the Kurile arcs. Low temperature gas samples from the Central American arc have δ37Cl values generally between −2 and 2‰, whereas high-temperature fumaroles (>100°C) range from 4 to 12‰, with several outliers. This is in contrast to the high-temperature fumaroles from the Kurile island Kudryavy which have slightly positive δ37Cl values, averaging 0.8‰ (±0.6, 1σ), and from our previous work on Izu and Mariana arc samples in which the δ37Cl values of fumarole and ash samples are similar to each other and negative. Assuming that the source for the high-T Central American fumaroles has typical subduction δ37Cl values (−2.5 to 1‰), then there must be a large Cl isotope fractionation in the near-surface fumarolic system. The most likely fractionation mechanism for the high δ37Cl values is between Cl− aq −HCl(g), but published theoretical fractionation for this pair is only ∼1.5‰, insufficient to explain the large range of values observed in the fumaroles. Three experiments were undertaken in order to identify a process that could cause the wide range of δ37Cl values observed in the high-temperature fumaroles. Results are the following: (1) A sub-boiling equilibration experiment between aqueous chloride and HCl gas had , in agreement with the theoretical calculations. (2) Evaporation of HCl(g) from hydrochloric acid at room temperature had fractionation in the opposite sense, with a . (3) A ‘synthetic fumarole’ gave large positive fractionations up to 9‰, with 37Cl strongly partitioned into the vapor phase. The ‘fumarole’ experiments were made by bubbling dry air through boiling hydrochloric acid in an Erlenmeyer flask, and collecting the evolved HCl(g) in a second ‘downstream’ flask filled with distilled water. This extreme enrichment is likely due to a distillation process in which 37Cl-enriched HCl(g) is stripped from the hydrochloric acid followed by a significant fraction of the light HCl(g) redissolving into the constantly condensing water vapor on the walls of the first flask. This distillation experiment creates a Cl isotope fractionation that is the same order of magnitude as observed in the high-temperature fumaroles in Central America. These results suggest that there must be a H2O liquid–vapor region in the sub-surface fumarole conduit where light Cl is stripped from the HCl gas as it passes through the fumarole. Similar 37Cl enrichments are expected in fossil epithermal boiling systems. [Copyright &y& Elsevier]

A concept of an accelerator mass spectrometer intended for the Siberian Branch of the Russian Academy of Sciences is suggested. Preliminary tests have been conducted, and a carbon isotope having a mass of 14 amu has been detected in a charcoal sample. [ABSTRACT FROM AUTHOR]

In the DEVIS tracking experiment that is being performed at the Institute of Theoretical and Experimental Physics (ITEP, Moscow, Russia) and which is devoted to searches for 136Xe double-beta decay, the 222Rn concentration is measured in xenon samples with different content of the isotope 136Xe. The number of probable double-electron events from 214Bi decay mimicking the double-beta decay of 136Xe is estimated. [ABSTRACT FROM AUTHOR]