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  Subjects -> ENGINEERING (Total: 1963 journals)
    - CHEMICAL ENGINEERING (151 journals)
    - CIVIL ENGINEERING (149 journals)
    - ELECTRICAL ENGINEERING (82 journals)
    - ENGINEERING (1120 journals)
    - ENGINEERING MECHANICS AND MATERIALS (290 journals)
    - HYDRAULIC ENGINEERING (45 journals)
    - INDUSTRIAL ENGINEERING (52 journals)
    - MECHANICAL ENGINEERING (74 journals)

CHEMICAL ENGINEERING (151 journals)                  1 2     

ACS Combinatorial Science     Full-text available via subscription   (Followers: 7)
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials     Hybrid Journal   (Followers: 3)
Acta Polymerica     Hybrid Journal   (Followers: 6)
Additives for Polymers     Full-text available via subscription   (Followers: 18)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 4)
Advanced Chemical Engineering Research     Open Access   (Followers: 7)
Advances in Applied Ceramics     Partially Free   (Followers: 2)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 15)
Advances in Chemical Engineering and Science     Open Access   (Followers: 21)
Advances in Polymer Technology     Hybrid Journal   (Followers: 10)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 1)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 9)
Anti-Corrosion Methods and Materials     Hybrid Journal   (Followers: 4)
Applied Petrochemical Research     Open Access   (Followers: 3)
Asia-Pacific Journal of Chemical Engineering     Hybrid Journal   (Followers: 6)
Biochemical Engineering Journal     Hybrid Journal   (Followers: 8)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 5)
BMC Chemical Biology     Open Access   (Followers: 4)
Brazilian Journal of Chemical Engineering     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Carbohydrate Polymers     Hybrid Journal   (Followers: 8)
Catalysts     Open Access   (Followers: 6)
Chemical and Petroleum Engineering     Hybrid Journal   (Followers: 7)
Chemical and Process Engineering     Open Access   (Followers: 3)
Chemical and Process Engineering Research     Open Access   (Followers: 5)
Chemical Communications     Full-text available via subscription   (Followers: 27)
Chemical Engineering & Technology     Hybrid Journal   (Followers: 24)
Chemical Engineering and Processing: Process Intensification     Hybrid Journal   (Followers: 9)
Chemical Engineering and Science     Open Access   (Followers: 2)
Chemical Engineering Communications     Hybrid Journal   (Followers: 10)
Chemical Engineering Journal     Hybrid Journal   (Followers: 16)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 15)
Chemical Engineering Science     Hybrid Journal   (Followers: 9)
Chemical Geology     Hybrid Journal   (Followers: 9)
Chemical Papers     Hybrid Journal   (Followers: 3)
Chemical Product and Process Modeling     Full-text available via subscription   (Followers: 3)
Chemical Reviews     Full-text available via subscription   (Followers: 252)
Chemical Society Reviews     Full-text available via subscription   (Followers: 26)
Chemical Technology     Open Access   (Followers: 4)
ChemInform     Hybrid Journal   (Followers: 3)
Chemistry & Industry     Hybrid Journal   (Followers: 2)
Chemistry Central Journal     Open Access   (Followers: 5)
Chemistry of Materials     Full-text available via subscription   (Followers: 162)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 6)
ChemSusChem     Hybrid Journal   (Followers: 7)
Chinese Chemical Letters     Full-text available via subscription   (Followers: 1)
Chinese Journal of Chemical Engineering     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemical Physics     Hybrid Journal   (Followers: 1)
Coke and Chemistry     Hybrid Journal  
Coloration Technology     Hybrid Journal   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 8)
Computer Aided Chemical Engineering     Full-text available via subscription   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 7)
Corrosion Engineering, Science and Technology     Hybrid Journal   (Followers: 18)
Corrosion Reviews     Full-text available via subscription   (Followers: 4)
Crystal Research and Technology     Hybrid Journal   (Followers: 2)
Current Opinion in Chemical Engineering     Open Access   (Followers: 2)
Education for Chemical Engineers     Hybrid Journal   (Followers: 4)
European Polymer Journal     Hybrid Journal   (Followers: 41)
Fibers and Polymers     Full-text available via subscription   (Followers: 3)
Focusing on Modern Food Industry     Open Access   (Followers: 3)
Frontiers of Chemical Science and Engineering     Hybrid Journal   (Followers: 1)
Geochemistry International     Hybrid Journal  
High Performance Polymers     Hybrid Journal  
Indian Chemical Engineer     Hybrid Journal   (Followers: 3)
Indian Journal of Chemical Technology (IJCT)     Open Access   (Followers: 12)
Industrial & Engineering Chemistry     Full-text available via subscription   (Followers: 9)
Industrial & Engineering Chemistry Research     Full-text available via subscription   (Followers: 16)
Industrial Chemistry Library     Full-text available via subscription   (Followers: 4)
International Journal of Chemical and Petroleum Sciences     Open Access   (Followers: 1)
International Journal of Chemical Engineering     Open Access   (Followers: 6)
International Journal of Chemical Reactor Engineering     Full-text available via subscription   (Followers: 3)
International Journal of Chemical Technology     Open Access   (Followers: 3)
International Journal of Chemoinformatics and Chemical Engineering     Full-text available via subscription   (Followers: 2)
International Journal of Food Science     Open Access   (Followers: 2)
International Journal of Industrial Chemistry     Open Access  
International Journal of Polymeric Materials     Hybrid Journal   (Followers: 3)
International Journal of Science and Engineering     Open Access   (Followers: 7)
International Journal of Waste Resources     Open Access   (Followers: 3)
ISRN Chemical Engineering     Open Access   (Followers: 4)
ISRN Polymer Science     Open Access   (Followers: 11)
Journal of Applied Crystallography     Hybrid Journal   (Followers: 4)
Journal of Applied Electrochemistry     Hybrid Journal   (Followers: 6)
Journal of Applied Polymer Science     Hybrid Journal   (Followers: 155)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 7)
Journal of Chemical & Engineering Data     Full-text available via subscription   (Followers: 6)
Journal of Chemical Ecology     Hybrid Journal   (Followers: 1)
Journal of Chemical Engineering     Open Access   (Followers: 3)
Journal of Chemical Engineering and Materials Science     Open Access  
Journal of Chemical Science and Technology     Open Access   (Followers: 1)
Journal of Chemical Sciences     Partially Free   (Followers: 13)
Journal of Chemical Technology & Biotechnology     Hybrid Journal   (Followers: 2)
Journal of Chemical Theory and Computation     Full-text available via subscription   (Followers: 9)
Journal of Coatings     Open Access   (Followers: 2)
Journal of Crystallization Process and Technology     Open Access   (Followers: 5)
Journal of Food Measurement and Characterization     Hybrid Journal  
Journal of Fuel Chemistry and Technology     Full-text available via subscription   (Followers: 5)
Journal of Fuels     Open Access  
Journal of Geochemical Exploration     Hybrid Journal  

        1 2     

Journal Cover Geochemistry International
   Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1556-1968 - ISSN (Online) 0016-7029
     Published by Springer-Verlag Homepage  [2208 journals]   [SJR: 0.401]   [H-I: 13]
  • Migration of Fe atoms in crystalline (Si) and amorphous (SiO       class="a-plus-plus">2) materials at their
           irradiation and heating
    • PubDate: 2014-07-01
       
  • Mechanism and hydrogeochemical conditions of the gaylussite formation in
           the Doroninskaya Group lakes, Eastern Transbaikal region
    • PubDate: 2014-07-01
       
  • The tritium-helium-3 method and its application to groundwater dating by
           the example of the Kirovsk mine region, Murmansk oblast
    • Abstract: Abstract The measurement of 3H, 3He, 4He, and 20Ne concentrations in waters at the Tsentralny pumping station (southern Khibiny massif, Kola Peninsula) showed that they are a mixture of young (>90%) and old (<10%) waters. The excess noble gas component from the young water is caused by the dissolution of air bubbles trapped during recharge in the unsaturated zone. The 3H-3He(3H) age of the young water is 21 ± 1.5 yr. The U-Th-4He age of the old water is about 50 ka. The high concentrations of helium and some toxic elements (e.g., aluminum) in this old water are caused by dissolution of the alkaline rocks of the Khibiny massif as a result of water-rock interaction.
      PubDate: 2014-07-01
       
  • Migration of dissolved trace elements in the mixing zone between Volga
           
    • Abstract: Abstract Based on natural observations over many years, the distribution of dissolved nutrients and trace elements was analyzed in the mixing zone between the freshwater of the Volga River and Caspian seawater. Most of the trace elements (Li, Rb, Cs, B, F, Br, I, Ga, Sc, Y, Co, Ni, Cu, Cd, Ag, V, As, Sb, Bi, Mo, W, and U) show a conservative behavior. During the period of the highest bioproductivity, dissolved phosphates and silica are intensely removed from solution (up to 60–90 and 46–82% of their supply by river runoff, respectively) mostly owing to uptake by aquatic organisms. The distribution of dissolved strontium was assigned to the weakly nonconservative type, because a minor excess of its content above the lines of conservative mixing (8–18%) was observed in some years; perhaps, this is related to different water transformation at the areas of moving and stagnant water in the delta and offshore mouth zone. Barium is characterized by additional input into the solution (up to 52%) in the regions of medium salinity owing to ion exchange reactions in the absorbed complex of river suspended material. The migration of dissolved species of aluminum, manganese, and iron in the mixing zone of Volga and Caspian waters is probably controlled by the coagulation and flocculation of organic and organo-mineral colloids, which is indicated by a sharp decrease in the content of these elements during the initial stage of salinization (59, 91, and 74%, respectively) followed by a plateau. The most complicated distribution was observed for titanium, lead, and rare earth elements (REE), the concentrations of which showed intense removal from the solution (up to 64–88% Ti, 52–87% Pb, and 66–83% REE) followed by a gradual increase, which is probably related to the elevated contents of these elements in the water of the northern Caspian above a local minimum in the zone of active flocculation of colloids.
      PubDate: 2014-07-01
       
  • Seasonal and interannual variations of water chemistry in the headwater
           streams of the Angara River (Baikal) from 1950 to 2010
    • Abstract: Abstract The study addressed seasonal and interannual variations in the components of the trophic status (organic carbon, nitrogen and phosphorus; silica; suspended matter; and chlorophyll-a) and ionic composition (bicarbonates, sulfates, chlorides, calcium, magnesium, sodium, and potassium) in the headwater streams of the Angara River since the 1950s. The results show that the concentrations and seasonal variations of these components and long-term trends of their mean annual concentrations resulted from the interplay of biological, hydrological, and anthropogenic processes operating in Lake Baikal and reflect the current ecological state of the lake.
      PubDate: 2014-07-01
       
  • Magmatic sources of dikes and veins in the Moncha Tundra Massif, Baltic
           Shield: Isotopic-geochronologic and geochemical evidence
    • Abstract: Abstract The dike-vein complex of the Moncha Tundra Massif comprises dolerites, gabbro-pegmatites, and aplites. The dolerite dikes are classified into three groups: high-Ti ferrodolerites, ferrodolerites, low-Ti and low-Fe gabbro-dolerites. The U-Pb age of the ferrodolerites is 2505 ± 8 Ma, and the amphibole-plagioclase metagabbroids hosting a ferrodolerite dike are dated at 2516 ± 12 Ma. Data on the U-Pb isotopic system of zircon from the gabbro-pegmatites and titanite from the aplites indicate that the late magmatic evolution of the Moncha Tundra Massif proceeded at 2445 ± 1.7 Ma, and the youngest magmatic events in the massif related to the Svecofennian orogeny occurred at 1900 ± 9 Ma. The data obtained on the Sm-Nd and Rb-Sr isotopic systems and the distribution of trace elements and REE in rocks of the dike-vein complex of the massifs provide insight into the composition of the sources from which the parental magmas were derived. The high-Ti ferrodolerites were melted out of a deep-sitting plume source that contained an asthenospheric component. The ferrodolerites were derived from a mantle MORB-type source that contained a crustal component. The parental melts of the gabbro-dolerites were melted out of the lithospheric mantle depleted in incompatible elements after Archean crust-forming processes above an ascending mantle plume, with the participation of a crustal component. The gabbro-dolerites and the rocks of the layered complex of the Moncha Tundra Massif exhibit similar geochemical characteristics, which suggest that their parental melts could be derived from similar sources but with more clearly pronounced crustal contamination of the parental melts of the rocks of the massif itself. The geochemical traits of the gabbro-pegmatites are thought to be explained not only by the enrichment of the residual magmas in trace elements and a contribution of a crustal component but also by the uneven effect of sublithospheric mantle sources. The aplites were derived from a sialic crustal source.
      PubDate: 2014-07-01
       
  • Inclusions in chloride xenoliths from the Udachnaya-East Kimberlite
    • PubDate: 2014-07-01
       
  • Sequence of geologic events in the central and northeastern parts of the
           Lapland Granulite Belt: Isotopic geochemical zircon data and results of
           geological-petrological studies
    • Abstract: Abstract Geological and petrological studies of rocks were conducted to reproduce the succession of endogenic processes in the central and northeastern parts of the Lapland Granulite Belt along the course of the Lotta River. Mineralogical-geochemical data on zircon from these rocks (the anatomy of zircon crystals seen in BSE and CL imagery; U, Th, Hf, and Y concentrations; and REE patterns) and their crystallization temperatures (calculated using the Ti concentration) make it possible to correlate the newly obtained geochronologic data with the sequence of metamorphic events inferred from petrological data. Three major episodes of enderbite-forming processes are distinguished: (i) early episode at 1.99 Ga, (ii) main episode at 1.940–1.925 Ga; and (iii) late episode at 1.89 Ga. The early medium-pressure metamorphic episode is dated at 1.97–1.96 Ga. The diatexis of the quartz-feldspar granulites with the derivation of garnet plagioclase leucogranites took place at 1.917–1.909 Ga.
      PubDate: 2014-07-01
       
  • Mesozoic-cenozoic sedimentation in the circum-arctic belt. 1.
           Triassic-Jurassic
    • Abstract: Abstract Data from the literature were used to revise a set of lithofacies maps for the Triassic-Jurassic epochs published by V.E. Khain, A.B. Ronov, and A.N. Balukhovskii in 1983. The study area is the Circum-Arctic belt, whose present-day northern boundary lies along the shelf break, and the southern boundary, at a latitude of 60° N. For the purpose of our study we used a simplified legend, which does not show climatic and tectonic features and emphasizes lithofacies zones. For each map, we calculated areas and volumes of sediments of the identified lithofacies zones and particular types of sediments. Using these data, we estimated the masses of dry sediment and rates of sediment accumulation. Trends in the distribution of the quantitative parameters of the Circum-Arctic belt were compared with global trends driven by tectonic and climatic changes. The contributions of regional-scale characteristics of sediment accumulation were identified. The results of this study indicate that global trends played a dominant role in regional sedimentation history. Two stages, Triassic and Jurassic, were distinguished in the history of sedimentation.
      PubDate: 2014-06-01
       
  • Physicochemical formation parameters of hydrothermal mineral deposits:
           
    • Abstract: Abstract Information from a database, which was compiled and continuously updated by the authors of this paper and now includes information from 19500 publication on fluid and melt inclusions in minerals, is used to summarize results on the physicochemical formation parameters of hydrothermal Au, Ag, Pb, and Zn deposits. The database provides information on fluid inclusions in minerals from 970 Pb-Zn, 220 Au-Ag-Pb-Zn, and 825 Au-Ag deposits in various settings worldwide. Histograms for the homogenization temperatures of fluid inclusion are presented for the most typical minerals of the deposits. In sphalerite, most homogenization temperatures (1327 measurements) of fluid inclusions lie within the range of 50–200°C with a maximum at 100–200°C for this mineral from Pb-Zn deposits and within the range of 100–350°C (802 measurements) with a maximum at 200–300°C for this mineral from Au deposits. Data are presented on fluid pressures at Au (1495 measurements) and Pb-Zn (180 measurements) deposits. The pressure during the preore, ore-forming, and postore stages at these deposits ranged from 4–10 to 6000 bar. The reason for the high pressures during preore stages at the deposits is the relations of the fluids to acid magmatic and metamorphic processes. More than 70% of the fluid pressures values measured at Pb-Zn deposits lie within the range of 1–1500 bar. Au-Ag deposits are characterized by higher fluid pressures of 500–2000 bar (61% of the measurements). The overall ranges of the salinity and temperature of the mineral-forming fluid at Au-Ag (6778 measurements) and Pb-Zn (3395 measurements) deposits are 0.1–80 wt % equiv. NaCl and 20–800°C. Most measurements (∼64%) for Au-Ag deposits yield fluid salinity <10 wt % equiv. NaCl and temperatures of 200–400°C (63%). Fluids at Pb-Zn deposits are typically more saline (10–25 wt % equiv. NaCl, 51% measurements) and lower temperature (100–300°C, 74% measurements). Several measurements of the fluid density fall within the range of 0.8–1.2 g/cm3. The average composition of volatile components of the fluids was evaluated by various techniques. The average composition of volatile components of fluid inclusions in minerals is calculated for hydrothermal W, Au, Ag, Sn, and Pb-Zn deposits, metamorphic rocks, and all geological objects. The Au, Ag, Pb, and Zn concentrations in magmatic melts and mineral-forming fluids is evaluated based on analyses of individual inclusions.
      PubDate: 2014-06-01
       
  • Thermal history of the Murzuq Basin, Libya, and generation of hydrocarbons
           in its source rocks
    • Abstract: Abstract The history of burial, temperature variations, and organic maturation in the sedimentary rocks of the Murzuq Basin in southwestern Libya was numerically reconstructed for eight wells and one pseudowell along northeast-southwest and northwest-southeast profiles across the basin. The reconstruction was performed using the GALO system for basin modeling taking into account that the basin lithosphere underwent repeated tectonic and thermal activation. The modeling allowed us to refine the reconstructions of the thermal history of the basin and assessment of its hydrocarbon potential obtained by previous models, which assumed a constant temperature gradient during the whole period of basin development. The Murzuq Basin is characterized by moderate basement subsidence (2200–2800 m), which would have corresponded in an ordinary basin to immature or early mature organic matter. However, the history of the basin included several periods of extensive uplift and subsidence, which were accompanied by the erosion of the sedimentary cover and thermal activation of the lithosphere. This resulted in variations in organic matter maturity reached in different segments of the basin and a peculiar distribution of the degree of maturation, which is higher at the flanks of the Murzuq Basin compared with the same rocks from deeper buried zones. Our modeling indicated that the rocks of the Tanezzuft Formation could generate significant volumes of liquid hydrocarbons at some areas of the basin, but the situation is strongly dependent on the depth of rock burial and amplitude of erosion of the sedimentary cover at various areas of the basin.
      PubDate: 2014-06-01
       
  • Iodine and selenium speciation in natural waters and their concentrating
           at landscape-geochemical barriers
    • Abstract: Abstract Drinkable waters in Bryansk oblast are generally poor in I and Se. Possible I and Se speciation in the drinkable waters and their means of migration and concentration in soils at geochemically contrasting conditions are analyzed, and the possible reason for the high mobility of I is demonstrated to be predetermined not only by its occurrence in the form of iodide and organic complexes but also by solute mineral species (CaI+ and MgI+), with the former and the latter types of the complexes spread more widely in the polessky and opolny landscape types, respectively. Iodine complexation with alkali-earth cations under reduced neutral-weakly alkaline conditions facilitates, on the one hand, vertical iodine migration and, on the other hand, its precipitation on the carbonate barrier. The predominant solute species of Se in these environments is hydroselenide, which can form FeSe in the presence of significant Fe concentrations and be precipitated on the reduced barrier in soils of hydromorphic landscapes. The generally low total I and Se concentrations in the drinkable waters and the migration of solute compounds of radioactive I in the form of organic and inorganic complexes could likely result in a higher thyroid morbidity rate over the whole territory of Bryansk oblast, including areas contaminated with radioactive I isotopes after the accident at the Chernobyl nuclear power plant.
      PubDate: 2014-06-01
       
  • Donnayite-(Y) from the Albyn gold deposit, Russian Far East
    • PubDate: 2014-06-01
       
  • Estimation of the thermodynamic characteristics of the earth’s core
           using the embedded atom model
    • Abstract: Abstract Since there are only limited experimental data for the multicomponent composition of the Earth’s core, which may contain nickel, silicon, sulfur, oxygen, hydrogen, carbon, and other admixture elements, we applied the molecular dynamics method as an additional tool. This approach is currently limited to the analysis of one- and two-component systems. In order to estimate the validity of this method for modeling under the Earth’s core conditions, a hypothetical variant of core composition corresponding to the iron-sulfur binary system was considered, because there are sufficient experimental data for this system under low-pressure conditions. The proposed embedded atom potential allows adequate description of the thermodynamic properties of solid and liquid iron-sulfur solutions under the conditions of the Earth’s center, inner-outer core boundary, and core-mantle boundary. The calculations relied on the Preliminary Reference Earth Model (PREM) data for pressure and density of phases at the inner-outer core boundary. Molecular dynamics calculations showed that the hypothetical variant of iron-sulfur binary solutions can provide reasonable consistency with the PREM values of pressure, density, and sound velocity for all the above levels. For this variant, temperatures at the same levels and sulfur contents were determined. The sulfur content was constrained at 5 at % in the inner core and 11–12 at % in the outer core, and it is almost independent of coordinates in each part of the core. The uncertainty of the calculation of sulfur content is ±0.5%. For the accepted two-component variant, the calculated temperature is approximately 6700 K in the Earth’s center and 6325 K at the inner-outer core boundary; the temperature estimate for the core-mantle boundary is more uncertain and ranges from 3300 to 4325 K (the latter value is more probable). The deviation of the calculated sound velocity from the PREM data is 5–10%, and the calculated velocity is overestimated at the core-mantle boundary and underestimated at other levels. If sufficient experimental data are available, a similar computation method can be applied to other two-component models of the composition of the Earth’s core (for instance, iron-nickel, iron-silicon, iron-oxygen, etc.), whereas three- and multicomponent systems cannot currently be calculated using the molecular dynamics method. The calculations reported in this paper showed that the molecular dynamics method in combination with geophysical data allows us to analyze different hypothetical variants of the composition of the Earth’s core, provides additional information on the properties of the core material, and helps to reveal the variants of core composition that are inconsistent with the available natural data.
      PubDate: 2014-06-01
       
  • Comparison of major, volatile, and trace element contents in the melts of
           mid-ocean ridges on the basis of data on inclusions in minerals and
           quenched glasses of rocks
    • Abstract: Abstract Using our database on major, trace, and volatile element contents in melt inclusions in minerals and quenched glasses of volcanic rocks reported in the literature, we compared the mean contents of 71 chemical elements in melts from the mid-ocean ridges (MORB) of the Atlantic, Pacific, and Indian oceans and determined the mean MORB composition for all the oceans of the Earth (global MORB composition). Mean ratios of incompatible trace and volatile components (H2O/Ce, K2O/Cl, Nb/U, Ba/Rb, Ce/Pb, Nb/U, etc.) were calculated for magmatic melts from all the oceans. Variations of these parameters were estimated, and significant differences between the melts of the Atlantic and Pacific oceans were established.
      PubDate: 2014-05-01
       
  • Metacolloid pyrite-pitchblende veinlets of high-grade hydrothermal ores at
           the Dalmatovskoe uranium deposit, Transural Region, Russia: New data on
           the mineralogy, geochemistry, age, and uranium sources
    • Abstract: Abstract Micro to nano-scale structures of pockets of solidified uranium oxide gel were found for the first time and deciphered ontogenetically during electron-microscopic mineralogical study of four samples of high-grade uranium ores from the Dalmatovskoe deposit. Mineralogical-geochemical features of paragenesis and structural features are reported for unique hydrothermal veinlets consisting of variably crystallized gelpyrite and subveinlets of gel-pitchblende of several generations. Mineralogical features indicate repeated opening of veinlets during hydrothermal ore formation and provide insight into physical and chemical features of non-solidified gel, its mobility, and aggressive behavior during metasomatism. It was proposed that the veinlets are genetically related to the main hydrothermal sources and possibly to the endogenous uranium occurrence, which was formed owing to opening of main fault marked by paleoriver bed. The find of such veinlets is considered as evidence for repeated influx of hydrothermal uranium in the uranium ores of the sedimentary-epigenetic deposit simultaneously with accumulation and transformation of sediments, which made it possible to ascribe this deposit to the hydrothermal-sedimentary type. The depth of core sampling of high-grade ores corresponds to the “ore zone” of the Dalmatovskoe Deposit, near the Paleozoic basement. For this reason, the entire “zone” was ascribed to the specific endogenous metasomatic epihydrothermal occurrences, possibly, of elision nature, with approximate temperature of ore formation of 150–250°C.
      PubDate: 2014-05-01
       
  • Concentration dependence of water diffusion in obsidian and dacitic melts
           at high-pressures
    • Abstract: Abstract The diffusion of water in natural obsidian and model dacitic melts (Ab90Di8Wo2, mol %) has been studied at water vapor pressure up to 170 MPa, temperatures of 1200°C, H2O contents in melts up to ∼6 wt % using a high gas pressure apparatus equipped with a unique internal device. The experiments were carried out by a new low-gradient technique with application of diffusion hydration of a melt from fluid phase. The water solubility in the melts and its concentration along $C_{H_2 O} $ diffusion profiles were determined using IR microspectrometry by application of the modified Bouguer-Beer-Lambert equation. A structural-chemical model was proposed to calculate and predict the concentration dependence of molar absorption coefficients of the hydroxyl groups (OH−) and water molecules (H2O) in acid polymerized glasses (quenched melts) in the obsidian-dacite series. The water diffusion coefficients $D_{H_2 O} $ were obtained by the mathematical analysis of concentration profiles and the analytical solution of the second Fick diffusion law using the Boltzman-Matano method. It was shown experimentally that $D_{H_2 O} $ exponentially increases with a growth of water concentration in the obsidian and dacitic melts within the entire range of diffusion profiles. Based on the established quantitative correlation between $D_{H_2 O} $ and viscosity of such melts, a new method was developed to predict and calculate the concentration, temperature, and pressure dependences of $D_{H_2 O} $ in acid magmatic melts (obsidian, rhyolite, albite, granite, dacite) at crustal T, P parameters and water concentrations up to 6 wt %.
      PubDate: 2014-05-01
       
  • Geochemistry and chemical evolution of saline lakes of Western Mongolia
    • Abstract: Abstract This paper presents data on the major and trace element composition of saline lakes of western Mongolia. The main geochemical types of lakes distinguished in the study are soda-, chloride-, and sulfaterich lakes. Lake water equilibria with major carbonate, sulfate, chloride, and other rock-forming minerals were calculated. The results show that the major factors controlling the formation of each lake type include evaporation and water-rock interaction processes, and the latter factor plays a critical role in freshwater and soda lakes and only a minor role in chloride lakes. Special attention was given to the soda lakes and the factors controlling lake water chemistry.
      PubDate: 2014-05-01
       
  • Physicochemical mechanism of phosphorus redistribution in sediments of
           highly productive oceanic areas: Experimental modeling data
    • PubDate: 2014-05-01
       
  • Thermodynamic properties of Fe-rich smectite-nontronite
    • Abstract: Abstract The results of thermochemical studies are reported for nontronite samples from the Pinares-de-Majari (Eastern Cuba) (Sample I) and Kempirsai serpentine massif (South Urals, Kazakhstan) (Sample II). The enthalpies of formation of dehydrated hydroxyl-bearing nontronites from elements were determined by melt dissolution calorimetry using high-temperature heat-flux Tiana-Calvet microcalorimeter: Δ f H el o (298.15 K): −4958 ± 13 kJ/mol for Mg0.4(Fe 1.5 3+ Mg0.4Ni0.1)[Si3.7Al0.3O10](OH)2 (I) and −5003.6 ± 8.0 kJ/mol for Mg0.3Na0.1Ca0.1(Fe 1.4 3+ Mg0.5Ni0.1)[Si3.7Al0.3O10](OH)2 (II). It was determined experimentally that the enthalpy of dehydration (removal of molecular adsorption and interlayer water) of the studied nontronites is 6 ± 2 kJ per 1 mole H2O. The enthalpy of formation of nontronite of theoretical composition Mg0.15Fe 2 3+ [Si3.7Al0.3]O10(OH)2 was estimated at −4750 kJ/mol. The Gibbs free energies of formation of the nontronites were calculated.
      PubDate: 2014-05-01
       
 
 
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