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Auzina L.I.,National Research Irkutsk State Technical University | Parshin A.V.,RAS Vinogradov Institute of Geochemistry
IOP Conference Series: Earth and Environmental Science | Year: 2016

The article describes the basic methodological elements of system-integrated approach to estimating water abundance in the upper hydrodynamic zone of Eastern Siberia territory to optimize water exploration. The technique is based on materials available at the pre-survey stages of exploration. When processing the information, the integrated geoinformation analysis has been used. © Published under licence by IOP Publishing Ltd. Source

Kulik D.A.,Paul Scherrer Institute | Wagner T.,ETH Zurich | Dmytrieva S.V.,Institute of Environmental Geochemistry | Kosakowski G.,Paul Scherrer Institute | And 4 more authors.
Computational Geosciences | Year: 2013

Reactive mass transport (RMT) simulation is a powerful numerical tool to advance our understanding of complex geochemical processes and their feedbacks in relevant subsurface systems. Thermodynamic equilibrium defines the baseline for solubility, chemical kinetics, and RMT in general. Efficient RMT simulations can be based on the operator-splitting approach, where the solver of chemical equilibria is called by the mass transport part for each control volume whose composition, temperature, or pressure has changed. Modeling of complex natural systems requires consideration of multiphase-multicomponent geochemical models that include nonideal solutions (aqueous electrolytes, fluids, gases, solid solutions, and melts). Direct Gibbs energy minimization (GEM) methods have numerous advantages for the realistic geochemical modeling of such fluid-rock systems. Substantial improvements and extensions to the revised GEM interior point method algorithm based on Karpov's convex programming approach are described, as implemented in the GEMS3K C/C++ code, which is also the numerical kernel of GEM-Selektor v.3 package (http://gems.web.psi.ch). GEMS3K is presented in the context of the essential criteria of chemical plausibility, robustness of results, mass balance accuracy, numerical stability, speed, and portability to high-performance computing systems. The stand-alone GEMS3K code can treat very complex chemical systems with many nonideal solution phases accurately. It is fast, delivering chemically plausible and accurate results with the same or better mass balance precision as that of conventional speciation codes. GEMS3K is already used in several coupled RMT codes (e.g., OpenGeoSys-GEMS) capable of high-performance computing. © 2012 Springer Science+Business Media B.V. Source

Mysovsky A.S.,RAS Vinogradov Institute of Geochemistry
International Journal of Quantum Chemistry | Year: 2012

We report a new mathematical result: it is possible to construct a spectral representation of the two particles Coulomb potential in the form of |r - r'| -1 = ∑ λ λg λ* (r) g λ(r'). We call this formula λ-decomposition. Two special nontrivial cases of λ-decomposition are reported together with the numerical analysis of the convergence for one of them. It is shown how λ-decomposition allows to construct a new fast algorithm for Hartree-Fock exchange operator calculation, in which the calculation of electron repulsion integrals (ERIs) is completely avoided. The connection between the new method and the resolution of identity and Cholesky decomposition based approaches has been established. Finally, the accuracy of ERIs evaluation within the new approach has been studied numerically. The results demonstrate that it is possible to achieve the accuracy of 10 -10 for the ERIs in wide range of their orbital exponents with relatively small number of terms in λ-decomposition. © 2011 Wiley Periodicals, Inc. Source

Chudnenko K.V.,RAS Vinogradov Institute of Geochemistry | Palyanova G.A.,Novosibirsk State University
Applied Geochemistry | Year: 2016

It is difficult to interpret the significance of some types of gold alloys without thermodynamic data describing the Au-Ag-Cu-Hg systems. Literature data on the content of copper and mercury in native gold and silver and that of silver and gold in native copper and mercury from gold deposits of different genesis were collected and analyzed. Activity coefficients of the solid solutions in Au-Ag-Cu-Hg quaternary system were estimated. The corresponding calculation module prepared for a "Selektor-C" software package allows calculation of the composition of quaternary solid solutions depending on the change in T,P,X-parameters. Ore formation scenarios were modeled for two objects: i) "hydrothermal" - on the example of formation of quaternary solid solutions in hydrothermal conditions at the Aitik Au-Ag-Cu porphyry deposit (Sweden); ii) "hydrothermal-hypergene" - on the example of formation of Au-Cu intermetallics at the Wheaton Creek placer deposit (Canada). The approach described in our work can be used as an additional tool for the analysis of the genesis of gold deposits and estimation of formation conditions of natural solid solutions of noble metals that are in many cases the main carriers of ore components. © 2015 Elsevier Ltd. Source

Shatsky V.S.,Novosibirsk State University | Malkovets V.G.,Okayama University | Belousova E.A.,Macquarie University | Skuzovatov S.,RAS Vinogradov Institute of Geochemistry
Precambrian Research | Year: 2015

U-Pb dating and Hf-isotope analysis of zircons and whole-rock Nd-isotope analyses were carried out on country rocks of the eclogite-gneiss complex of the North Muya dome in the Anamakit-Muya zone of the Baikal Muya accretionary fold belt. Zircons from garnet-biotite gneisses (Qtz+Kfsp+Pl+Bt+Grt) and garnet-biotite-muscovite schist (Pl+Kfsp+Bt+Mu+Grt+Qtz) were dated using the LA-ICP-MS technique. Based on U-Pb isotope data and CL images zircon grains were divided into three groups: detrital, magmatic and metamorphic zircons. Metamorphic zircons display no zoning or the cloudy zoning. The grains morphology together with the well-developed oscillatory zoning clearly identifies the igneous origin of magmatic zircons. The metamorphic zircons (ages 576-680Ma) have Th/U ratios varying from 0.271 to 0.004, whereas the ratio in magmatic zircons ranges from 0.779 to 0.11. Magmatic zircons from granite-gneisses of the North Muya dome exhibit a relatively narrow spread in the crystallization age with the major peak at ca 764Ma. Younger ages are interpreted as due to the partial resetting of U-Pb system during the subsequent metamorphic evolution. Detrital zircons from two-mica schist sample Mu-93-10 give ages of 1.88-2.66Ga. The oldest detrital zircon from this sample plots near concordia and has a 207Pb/206Pb age of 3.2Ga. Zircons from this sample are characterized by the widest scatter of eHf(t) values (from +13.9 to -15.3) and TCDM model ages (0.82-3.86Ga). Zircons from other samples have a much narrower ranges of eHf(t) (+11.6 to -0.7) and TCDM (0.85-1.52Ga). The involvement of older crustal material is also evident from the whole-rock Nd isotopic compositions. The gneisses and schists exhibit a range of Nd isotopic compositions with eNd(t) values ranging from -3.5 to +3.6 and tNd(DM) from 1.64 to 1.09Ga. The integration of the Hf-isotope data with the age spectra provides with the first evidence for the existence of Mesoarchean crust in the Baykal-Muya sector of the Central Asian Orogenic Belt. © 2015 Elsevier B.V. Source

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