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  Subjects -> ENGINEERING (Total: 1957 journals)
    - CHEMICAL ENGINEERING (150 journals)
    - CIVIL ENGINEERING (146 journals)
    - ELECTRICAL ENGINEERING (84 journals)
    - ENGINEERING (1124 journals)
    - ENGINEERING MECHANICS AND MATERIALS (284 journals)
    - HYDRAULIC ENGINEERING (43 journals)
    - INDUSTRIAL ENGINEERING (53 journals)
    - MECHANICAL ENGINEERING (73 journals)

CHEMICAL ENGINEERING (150 journals)                  1 2     

ACS Combinatorial Science     Full-text available via subscription   (7 followers)
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials     Hybrid Journal   (3 followers)
Acta Polymerica     Hybrid Journal   (4 followers)
Additives for Polymers     Full-text available via subscription   (17 followers)
Adhesion Adhesives & Sealants     Hybrid Journal   (3 followers)
Advanced Chemical Engineering Research     Open Access   (7 followers)
Advances in Applied Ceramics     Partially Free   (2 followers)
Advances in Chemical Engineering     Full-text available via subscription   (14 followers)
Advances in Chemical Engineering and Science     Open Access   (19 followers)
Advances in Polymer Technology     Hybrid Journal   (9 followers)
African Journal of Pure and Applied Chemistry     Open Access  
Annual Review of Analytical Chemistry     Full-text available via subscription   (8 followers)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (8 followers)
Anti-Corrosion Methods and Materials     Hybrid Journal   (3 followers)
Applied Petrochemical Research     Open Access   (3 followers)
Asia-Pacific Journal of Chemical Engineering     Hybrid Journal   (6 followers)
Biochemical Engineering Journal     Hybrid Journal   (8 followers)
Biomass Conversion and Biorefinery     Partially Free   (5 followers)
BMC Chemical Biology     Open Access   (4 followers)
Brazilian Journal of Chemical Engineering     Open Access   (2 followers)
Bulletin of the Chemical Society of Ethiopia     Open Access   (1 follower)
Carbohydrate Polymers     Hybrid Journal   (8 followers)
Catalysts     Open Access   (5 followers)
Chemical and Petroleum Engineering     Hybrid Journal   (7 followers)
Chemical and Process Engineering     Open Access   (3 followers)
Chemical and Process Engineering Research     Open Access   (5 followers)
Chemical Communications     Full-text available via subscription   (28 followers)
Chemical Engineering & Technology     Hybrid Journal   (24 followers)
Chemical Engineering and Processing: Process Intensification     Hybrid Journal   (9 followers)
Chemical Engineering and Science     Open Access   (2 followers)
Chemical Engineering Communications     Hybrid Journal   (10 followers)
Chemical Engineering Journal     Hybrid Journal   (16 followers)
Chemical Engineering Research and Design     Hybrid Journal   (15 followers)
Chemical Engineering Science     Hybrid Journal   (9 followers)
Chemical Geology     Hybrid Journal   (9 followers)
Chemical Papers     Hybrid Journal   (3 followers)
Chemical Product and Process Modeling     Full-text available via subscription   (3 followers)
Chemical Reviews     Full-text available via subscription   (186 followers)
Chemical Society Reviews     Full-text available via subscription   (26 followers)
Chemical Technology     Open Access   (4 followers)
ChemInform     Hybrid Journal   (3 followers)
Chemistry & Industry     Hybrid Journal   (2 followers)
Chemistry Central Journal     Open Access   (5 followers)
Chemistry of Materials     Full-text available via subscription   (139 followers)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (6 followers)
ChemSusChem     Hybrid Journal   (6 followers)
Chinese Chemical Letters     Full-text available via subscription   (1 follower)
Chinese Journal of Chemical Engineering     Full-text available via subscription   (3 followers)
Chinese Journal of Chemical Physics     Hybrid Journal   (1 follower)
Coke and Chemistry     Hybrid Journal  
Coloration Technology     Hybrid Journal   (1 follower)
Computational Biology and Chemistry     Hybrid Journal   (8 followers)
Computer Aided Chemical Engineering     Full-text available via subscription   (2 followers)
Computers & Chemical Engineering     Hybrid Journal   (6 followers)
Corrosion Engineering, Science and Technology     Hybrid Journal   (18 followers)
Corrosion Reviews     Full-text available via subscription   (4 followers)
Crystal Research and Technology     Hybrid Journal   (2 followers)
Current Opinion in Chemical Engineering     Open Access   (2 followers)
Education for Chemical Engineers     Hybrid Journal   (3 followers)
European Polymer Journal     Hybrid Journal   (41 followers)
Fibers and Polymers     Full-text available via subscription   (3 followers)
Focusing on Modern Food Industry     Open Access   (3 followers)
Frontiers of Chemical Science and Engineering     Hybrid Journal   (1 follower)
Geochemistry International     Hybrid Journal  
High Performance Polymers     Hybrid Journal  
Indian Chemical Engineer     Hybrid Journal   (3 followers)
Indian Journal of Chemical Technology (IJCT)     Open Access   (12 followers)
Industrial & Engineering Chemistry     Full-text available via subscription   (9 followers)
Industrial & Engineering Chemistry Research     Full-text available via subscription   (16 followers)
Industrial Chemistry Library     Full-text available via subscription   (4 followers)
International Journal of Chemical and Petroleum Sciences     Open Access   (1 follower)
International Journal of Chemical Engineering     Open Access   (6 followers)
International Journal of Chemical Reactor Engineering     Full-text available via subscription   (3 followers)
International Journal of Chemical Technology     Open Access   (3 followers)
International Journal of Chemoinformatics and Chemical Engineering     Full-text available via subscription   (2 followers)
International Journal of Food Science     Open Access   (2 followers)
International Journal of Industrial Chemistry     Open Access  
International Journal of Polymeric Materials     Hybrid Journal   (3 followers)
International Journal of Science and Engineering     Open Access   (7 followers)
International Journal of Waste Resources     Open Access   (3 followers)
ISRN Chemical Engineering     Open Access   (3 followers)
ISRN Polymer Science     Open Access   (10 followers)
Journal of Applied Crystallography     Hybrid Journal   (4 followers)
Journal of Applied Electrochemistry     Hybrid Journal   (6 followers)
Journal of Applied Polymer Science     Hybrid Journal   (124 followers)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (7 followers)
Journal of Chemical & Engineering Data     Full-text available via subscription   (6 followers)
Journal of Chemical Ecology     Hybrid Journal   (1 follower)
Journal of Chemical Engineering     Open Access   (3 followers)
Journal of Chemical Engineering and Materials Science     Open Access  
Journal of Chemical Science and Technology     Open Access   (1 follower)
Journal of Chemical Sciences     Partially Free   (13 followers)
Journal of Chemical Technology & Biotechnology     Hybrid Journal   (2 followers)
Journal of Chemical Theory and Computation     Full-text available via subscription   (8 followers)
Journal of Coatings     Open Access   (2 followers)
Journal of Crystallization Process and Technology     Open Access   (4 followers)
Journal of Food Measurement and Characterization     Hybrid Journal  
Journal of Fuel Chemistry and Technology     Full-text available via subscription   (5 followers)
Journal of Geochemical Exploration     Hybrid Journal  
Journal of Industrial and Engineering Chemistry     Hybrid Journal   (1 follower)

        1 2     

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  [2187 journals]   [SJR: 0.401]   [H-I: 13]
  • Geochemistry of dacitic volcanics in the Eastern Pontides (NE Turkey)
    • Abstract: Abstract Dacitic rocks that crop out around the Zigana Mountain (Gümüşhane) in the eastern Pontide (NE Turkey), are mainly composed of quartz, plagioclase, sanidine, amphibole, muscovite, and biotite as the main minerals. Zircon and rutile are the accessory minerals. Pyrite, chalcopyrite, and covellite are the opaque components. On the basis of trace-element data, dacites have been classified as Dacite-I and Dacite-II. Dacite-I is tholeitic-transitional, whereas Dacite-II is transitional-calc-alkaline. The geochemical variation can be explained by the fractionation of the common mineral phases, such as plagioclase, hornblende, magnetite, and apatite. Dacites also show island-arc properties, with negative Nb, Sr, P, and Ti anomalies. The trace-element distrubitions of the dacitic rocks reflect the typical characteristics of rocks from the subduction-related tectonic setting, with enrichment of large-ion lithofile elements and light rare-earth element, but depletion in high-field-strength elements. The dacitic rocks are developed through plagioclase ± hornblende-controlled fractionation from the same parental magma that settled in two successive stages and are derived from an enriched source, probably by the mixing of slab-derived and lithospheric melts.
      PubDate: 2014-04-01
       
  • Facies structure and quantitative parameters of pleistocene pelagic
           sedimentation in the Indian Ocean
    • Abstract: Abstract We compiled lithofacies maps for the early and middle-late Pleistocene (Eopleistocene and Neopleistocene, respectively) pelagic sedimentation of the Indian Ocean and a database for sediment thicknesses in the respective stratigraphic subdivisions. Using these data, we calculated areas, volumes, masses, and intensities of accumulation of main sediment types for both Pleistocene subdivisions. A comparison of the results confirmed a strong increase in the rate of terrigenous sedimentation. Special attention was given to the evolution of siliceous and carbonate sedimentation of the biogenic type.
      PubDate: 2014-04-01
       
  • Simulation of forsterite protonation by the interatomic potential method
    • Abstract: Abstract The interatomic potential method in an ionic approximation was used to model the protonation of forsterite crystals. The formation of isolated OH− groups in iron-free and iron-bearing crystals and neutral clusters of protonated cation vacancies was considered. It was shown that the presence of trivalent impurities may significantly facilitate protonation processes owing to their reduction to a divalent state or formation of clusters with cation vacancies. In most cases, charge balancing of hydrogen-bearing defects by magnesium vacancies is energetically favorable over that involving silicon vacancies.
      PubDate: 2014-04-01
       
  • Isotope and geochemical characteristics of rocks from the Oshurkovo
           apatite-bearing massif, Western Transbaikalia
    • Abstract: Abstract We present the results of a study on gabbroic rocks, syenites, pegmatites, carbonatites, and hydrothermal products of the Oshurkovo apatite-bearing massif. The results include Nd and Sr isotope ratios; the isotope compositions of carbon and oxygen in calcite; oxygen in apatite, magnetite, and silicate minerals (phlogopite, titanite, diopside, amphibole, K-feldspar, and quartz); sulfur in barite; and hydrogen in mica. The isotopic data are close to the EM-1 enriched mantle values and confirm a comagmatic relationship between the gabbros and carbonatites. The binary plot ɛNd vs. 87Sr/86Sr demonstrates strong differentiation between silicate rocks and carbonatites, as is the case with the other Late Mesozoic carbonatite occurrences of southwestern Transbaikalia. The oxygen isotope composition of all comagmatic phases also falls within the range of mantle values. A clear trend toward heavier oxygen and lighter carbon isotope compositions is observed in all successively emplaced phases, which is consistent with a trend defined by hydrothermal products formed under the influence of the parent magma chamber. Carbonates formed during the greenstone alteration of gabbroic rocks are enriched in the light oxygen isotope (δ18O from −2.8 to −7.3‰), suggesting a contribution of vadose water.
      PubDate: 2014-04-01
       
  • Reply to a comment in G. Meinhold “Geochemical discrimination of
           rutile from the Belomorian Mobil Belt”
    • PubDate: 2014-04-01
       
  • Morphology, composition, age and origin of carbonate spherulites from
           caves of Western Urals
    • PubDate: 2014-04-01
       
  • Geochemical discrimination of rutile from the Belomorian mobile belt
    • PubDate: 2014-04-01
       
  • Geochemical classification by means of mapping resultants
    • Abstract: Abstract The paper presents a new method for visualizing multidimensional numeric fields. The method consists in a special way of projecting analytical tests from the multidimensional space of attributes onto a single chart plane. The suggested technique proved to be efficient in interpreting geochemical data.
      PubDate: 2014-04-01
       
  • Geochemical features of ilmenites from the alkaline complexes of the
           Ukrainian Shield: LA-ICP MS data
    • Abstract: Abstract LA-ICP MS data are presented for ilmenites from different rocks of the alkaline complexes of the Ukrainian Shield (Chernigovka carbonatite, Oktyabr’skii, Malaya Tersa, and Southern Kal’chinskii gabbrosyenite massifs). Ilmenites from the early intrusive phases (alkaline pyroxenites, gabbroids, and ultramafic rocks) have the elevated contents of Cr, Co, Ni, and V, while ilmenites from later alkaline and nepheline syenites, monzonites, and carbonatites are significantly enriched in Nb and Ta, which is caused by change in the alkalinity of the mineral-forming medium. Zr shows the more intrinsic behavior: its content is higher in the ilmenites from basic and ultrabasic rocks than in those from the nepheline syenites and carbonatites. This is mainly caused by temperature conditions of the formation of differentiated alkaline complexes. The carbonatites contain magnesian ilmenite (up to 22 mol % MgTiO3). Variations of Mg contents in ilmentes are correlated with Mg number of mafic minerals and depend also on the iron oxidation state (amount of magnetite) in the carbonatites. In the alkaline massifs of the Ukrainian Shield, ilmenites usually have the low contents of hematite end member (3–7 mol %). Ilmenite serves as a sensitive indicator of temperature, oxygen fugacity, and alkalinity of the mineral-forming medium during crystallization.
      PubDate: 2014-04-01
       
  • Zn in hydrothermal systems: Thermodynamic description of hydroxide,
           chloride, and hydrosulfide complexes
    • Abstract: Abstract The paper presents critical analysis of literature data on the stability constants of aqueous species in the system Zn-O-H-S−II-Cl. In order to more accurately determine the composition and stability of chloride Zn complexes, additional experiments were carried out to determine the solubility of sphalerite ZnSc in chloride-sulfide solutions at 175°C and the saturated vapor pressure of the solution. Having processed the data, we obtained the thermodynamic properties at 25°C and parameters of the HKF (Helgeson-Kirkham-Flowers) equation of state (EoS) for hydroxide, chloride and hydrosulfide Zn complexes. The constants of sphalerite dissolution reactions with the formation of hydrosulfide and, particularly, chloride complexes increase with increasing temperature. The predominant Zn transport species in high-temperatures (>250°C) chloride-sulfide hydrothermal solutions are chloride complexes, first of all, ZnCl 4 2− . As the temperature decreases, the concentrations of complexes with smaller numbers of Cl− ligands increase. The region of weakly acidic to alkaline pH is dominated by hydrosulfide Zn complexes, but their concentrations in equilibrium with sphalerite are relatively low (a few ppm at 400°C and S concentrations <0.1 mol kg−1) and decreases with a temperature decrease. In the region dominated by chloride complexes, the concentration of dissolved Zn can amount to a few fractions of a percent at near-neutral pH, 400°C, and m(NaCl) = 1.0 and increases if the fluid becomes more acidic. An extremely important factor controlling the concentrations of dissolved Zn is temperature: cooling leads to the effective precipitation of sphalerite, particularly in the region dominated by chloride complexes. The thermodynamic properties of the solid phases and parameters of the HKF model for aqueous species in the system Zn-O-H-S-II-Cl are presented in the on-line version of the FreeGC database (http://www-b.ga.gov.au/minerals/research/methodology/geofluids/thermo/calculator/search.jsp), which enables calculating the Gibbs energy values of components of the system and reaction constants involving these components at PT parameters up to 600°C and 3 kbar.
      PubDate: 2014-03-01
       
  • Relationships between the color and chemical composition of quaternary
           bottom sediments from the southern part of the Mendeleev Rise and the
           continental slope of the East Siberian Sea
    • Abstract: Abstract This paper addresses the problem of relationships between the chemical composition and color of Quaternary marine sediments using the data of X-ray fluorescence analysis for the region of the Mendeleev Rise (Arctic Ocean). The contributions of sedimentation and diagenetic factors to color formation were estimated. It was shown that lithostratigraphic correlations should be performed (with certain limitations) using only sediment layers of dark brown and pink color.
      PubDate: 2014-03-01
       
  • Geochemistry of rocks in the Anuy metamorphic dome, Sikhote-Alin:
           Composition of the protoliths and the possible nature of metamorphism
    • Abstract: Abstract The paper presents geological, geochemical, and isotopic data on metamorphic rocks in the Anuy block (dome) in the Northern Sikhote-Alin and the surrounding sedimentary rocks of the Samarka accretionary prism. The geochemistry and isotopic composition of the amphibolite-facies metamorphic rocks (variably migmatized gneisses and crystalline schists) in the Anuy block and unmetamorphosed Jurassic-Cretaceous sediments surrounding the block are proved to be similar. All of them corresponded to the erosion products of the transitional-type crust (mature island arcs and active continental margins), have similar major- and trace-element compositions, and Nd model ages of 1.25–1.4 Ga. The geochemistry and isotopic parameters of metapelites in the Anuy block are principally different from those of analogous rocks in the Khanka Massif (the latter rocks are erosion products of the mature crust and have a Nd model age of 1.7–1.9 Ga). The metabasites, which are found as beds and lenses in gneisses and crystalline schists in the Anuy block and among sedimentary rocks surrounding the block, have a composition corresponding to oceanic basalts of the N- and E-MORB types. Based on the synthesis of geological, geochemical and isotopic data it was suggested that the Anuy block could be not a fragment of the basement of an ancient continent (as was believed previously) but rather a complex of the Early Cretaceous granite-metamorphic core of the Cordilleran type.
      PubDate: 2014-03-01
       
  • Chemical and isotopic characteristics of hydrocarbon gases from Mendeleev
           and Golovnin volcanoes, Kunashir Island
    • Abstract: Abstract This paper reports the analysis of the distribution of hydrocarbon and other gases in Mendeleev and Golovnin volcanoes and other occurrences of Kunashir Island. It was shown that, in addition to methane, the solfatara gases and gases dissolved in thermal waters contain ethane, propane, and butane. The volume concentration of methane in gas samples was no higher than 0.4 vol %. Carbon isotopes were analyzed in methane, ethane, and carbon dioxide in free and dissolved states. The hydrocarbon gases of Kunashir I. are of the thermogenic and metamorphogenic types, and their distribution depends on the position of springs relative to the eruptive centers of the volcanoes. Thermogenic gases are probably products of the high-temperature transformation of sedimentary organic matter buried during the formation of volcanic edifices. General gas geochemical characteristics are presented for Kuril volcanoes, and it was found that hydrocarbon generation in the sediments of the Kuril Basin increases toward volcanic edifices.
      PubDate: 2014-03-01
       
  • Petrology and geochemistry of plutonic rocks in the Northwest Pacific
           Ocean and their geodynamic interpretation
    • Abstract: Abstract The paper presents data on the petrology and geochemistry of plutonic rocks dredged from the Stalemate Fracture Zone, Northwest Pacific Ocean, during Cruise SO201-1 of the R/V “Sonne”. We proposed also the reconstruction of their formation conditions and interpretation of their tectonic evolution. The genesis of gabbroids found among plutonic rocks composing the Cretaceous-Paleogene basement of the northwestern part of the Pacific Ocean was related to magmatism at the ancient spreading center and provides record of the evolution of the parental magmatic melts of N-MORB. Along with related peridotites, basalts, and dolerites, these rocks can be attributed to the disintegrated the Cretaceous-Paleogene oceanic lithosphere of the Pacific Ocean. The shallow mantle beneath the ancient oceanic crust of this area is made up of depleted magmatic spinel lherzolite, harzburgite, and dunite. The fact that gabbro-diorite and diorite that are not genetically related to the rocks of the Cretaceous-Paleogene basement of the Northwest Pacific occur at the eastern termination of the Stalemate Fracture Zone possibly reflects the complicated structure of the tectonic collage of rocks of different age that were produced in different geodynamic environments and were later tectonically brought together near the frontal portion of the Aleutian island arc. Judging by the isotopic-geochemical characteristics of these rocks, they cannot be classed with the family of oceanic plagiogranites. Deformations of the oceanic basement can be discerned throughout the whole Stalemate Fracture Zone as brecciation and large-amplitude vertical displacements within the oceanic lithosphere.
      PubDate: 2014-03-01
       
  • Secondary mineral-forming processes in natural—anthropogenic
           hydrogeological systems at sulfide deposits. Simulation of the origin of
           the phase (Fe,Mg)SO4 ·
           7H2O in the course of sulfide
           oxidation at the Degtyarka copper sulfide deposit
    • Abstract: Abstract Data on the decommissioned Degtyarka Cu sulfide deposit, Urals, confirm the hypothesis that the flooding of abandoned mine workings is associated with the synthesis of secondary sulfates. Numerical simulation of hydrogeochemical processes in the rock—water system imitating the flooding of an underground void makes it possible to evaluate the conditions under which kirovite (Fe,Mg)SO4 · 7H2O and melanterite are formed at the oxidation of ore sulfides. Secondary sulfates are formed when the redox potential of the system is transformed from reducing to oxidizing within the stability field of Fe(II) species. The Fe/Mg ratio of the kirovite (Fe,Mg)SO4 · 7H2O is controlled first of all by the percentage of sulfides in the rock—water system, the rock/water ratio, the openness of the system with respect to atmospheric gases, and the temperature.
      PubDate: 2014-02-01
       
  • Ore mineralization in volcanic rocks from the submarine rises of the Sea
           of Japan
    • Abstract: Abstract The electron microprobe investigation of volcanic rocks from the submarine rises of the Sea of Japan revealed for the first time numerous inclusions of small grains containing metals (Cu, Zn, Sn, Ni, Pb, As, Cr, W, Ti, Ta, Fe, and Ag), mainly as native elements, intermetallic compounds, phosphides, oxides, sulfides, and sulfates. These grains are usually confined to the walls of microscopic fractures and pores or fill microscopic cavities and interstices in the groundmass and in rock-forming minerals. Taking into account that native metals, intermetallic compounds, and phosphides are indicative of a high-temperature gaseous fluid, it can be supposed that such a fluid was the source of metals.
      PubDate: 2014-02-01
       
  • Mercury as an indicator of modern ore-forming gas—hydrothermal
           systems, Kamchatka
    • Abstract: Abstract New data are discussed on the distribution of mercury in the host volcanosedimentary and igneous rocks, hydrothermal—metasomatic rocks, and all types of modern newly formed materials (hydrothermal clays, argillized soil—pyroclastic beds, siliceous and limonite—hematite covers, bottom sediments, salt ‘sweat-outs’ of various compositions, etc.) typical of the supergene zone of geothermal deposits. By the example of the Nizhne-Koshelevskii (vapor-dominated) and Pauzhetka (water-type) geothermal deposits and thermal fields of the Koshelevskii volcanic massif and Kambal’nyi volcanic range (southern Kamchatka), the role of mercury was illustrated as an indicator element of the temperature, phase state, and dynamics of hydrothermal systems; intensity of rock argillization; and relative age (maturity) of geothermal deposits and thermal anomalies.
      PubDate: 2014-02-01
       
  • Isotope geochemistry and geochronology of the gabbro of the Volkovsky
           Massif, Urals
    • Abstract: Abstract 40Ar-39Ar, Sm-Nd, U-Pb, and Lu-Hf isotope data are reported on the gabbro of the Volkovsky Massif, the only massif of the Uralian Platinum Belt wherein economic copper-iron-vanadium and high-grade gold-palladium mineralization is present. The massif is made up of gabbro blocks with concentrically zoned structure and diorite intrusions in its core. In the northeast and southwest, the gabbro is cut by syenite of the Kushva Massif. Gabbro blocks mainly consist of the olivine-anorthite gabbro, while labradorite two- pyroxene gabbro intersects both olivine-anorthite gabbro and Ti-magnetite and copper-PGE mineralization developed in them. The study of both gabbro types by Sm-Nd isochron and U-Pb (SHRIMP II) zircon methods with subsequent REE and Lu-Hf isotope analysis of zircon made it possible to date reliably (428 ± 7 Ma (SHRIMP) and 436 ± 21 Ma (Sm-Nd)) postore labradorite gabbro and, correspondingly, the upper age limit of the mineralization of the Volkovsky Massif. Ore-bearing olivine-anorthite gabbro contain four different-age zircon populations: 2682 ± 37–972 ± 18 Ma, 655 ± 15 to 565 ± 9 Ma; 450 ± 12 Ma, and 343 ± 8 Ma. Hf-Nd isotope systematics showed that zircon with an age of 450 ± 12 Ma presumably marks the formation age of the rocks, the older zircon was trapped, while zircon with an age of 343 ± 8 Ma was formed during low-temperature transformation of the rock and sometimes contains excess radiogenic Hf. Proterozoic xenogenic zircon was inherited from diverse rocks of ancient crust, while the oldest grain with an age of 2065 Ma was possibly formed in a deep mantle source. Vendian zircon was presumably also entrapped, and its morphology and geochemistry point to the crystallization from a basaltic melt. The abundance of pre-Paleozoic zircon in the olivine-anorthite gabbro suggests significant contribution of ancient material in their petrogenesis. This material could serve as source of ore components (metals and sulfur) for unique copper-sulfide gold-PGE mineralization of the Volkovsky Massif.
      PubDate: 2014-02-01
       
  • Systematic variations in the composition of volcanic rocks in
           tectono-magmatic seamount chaines in the Brazil Basin
    • Abstract: Abstract Data on the composition of rocks in linear tectono-magmatic rises in the Brazil Basin indicate that volcanic rocks in the Vitoria—Trindade seamount chain were derived from a mantle reservoir unevenly enriched in phosphorus under the effect of melts close to subalkaline picrobasalt. These melts contained much of the EM I mantle component because the plume material was contaminated with continental lithospheric component. A long-lived isotopic homogeneity of the source is typical of the whole structure, including the Trindade and Martin Vaz Islands and the Abrolhos Plateau. The analogous isotopic ratios of rocks at the Fernando de Noronha Islands are reportedly explained by a similar mechanism of melt derivation and the similar evolution of the mantle plume material, which was originally situated beneath the South American continent. Compared to the melts of volcanic rocks of all other seamounts discussed herein, the parental melts of volcanics at the Victoria—Trindade Seamounts were derived at lower degrees of melting of enriched source material at a greater depth. The overwhelming majority of volcanic rocks at the northern chain of the Bahia Seamounts were produced by melts generated with the involvement of material of the HIMU type. At the same time, one of our rock samples was derived from a source of composition close to DM with a certain admixture of enriched material like EM I. The mantle source of rocks of the Pernambuco Seamounts consisted of a mixture of DM and HIMU material with a certain admixture of EM I (or, perhaps, EM II). The 10°–11° S Seamounts were formed near the MAR axial zone at the decompressional melting of chemically homogeneous mantle source that consisted of DM material with an admixture of EM I (or, perhaps, EM II) component.
      PubDate: 2014-02-01
       
  • Geochemical characterization of adsorbed light gaseous alkanes in near
           surface soils of the eastern Ganga basin for hydrocarbon prospecting
    • Abstract: Abstract This study aims to assess the hydrocarbon potential of Ganga basin utilizing the near surface geochemical prospecting techniques. It is based on the concept that the light gaseous hydrocarbons from the oil and gas reservoirs reach the surface through micro seepage, gets adsorbed to soil matrix and leave their signatures in soils and sediments, which can be quantified. The study showed an increased occurrence of methane (C1), ethane (C2) and propane (C3) in the soil samples. The concentrations of light gaseous hydrocarbons determined by Gas Chromatograph ranged (in ppb) as follows, C1: 0–519, C2: 0–7 and C3: 0–2. The carbon isotopic (VPDB) values of methane varied between −52.2 to −27.1‰, indicating thermogenic origin of the desorbed hydrocarbons. High concentrations of hydrocarbon were found to be characteristic of the Muzaffarpur region and the Gandak depression in the basin, signifying the migration of light hydrocarbon gases from subsurface to the surface and the area’s potential for hydrocarbon resources.
      PubDate: 2014-01-01
       
 
 
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