Vol 64, No 10 (2019)


Experimental modeling of formation of native metals (Fe, Ni, Co) in the earth’s crust by the interaction of hydrogen with basaltic melts

Persikov E.S., Bukhtiyarov P.G., Aranovich L.Y., Nekrasov A.N., Shaposhnikova O.Y.


In continuation of our early works, an experimental study of the kinetics and interaction mechanisms in the hydrogen-basalt melt system at a hydrogen pressure of 100 MPa and temperature of 1250°C carried out. It was found in kinetic experiments that, despite the high reduction potential of the H2-melt system, the hydrogen oxidation reactions and the complete reduction of Fe oxides in the melt do not go to the end. As a result, initially homogeneous basalt melt becomes heterogeneous: H2O is formed in the fluid phase; H2O is dissolved in the basalt melts, and a small metal separation of the liquation structure formed at a temperature significantly lower than the melting temperature of the metal phases (Fe, FeNiCo alloy). The structure and dimensions of the experimentally established metal separations agree well with the natural data on the findings of small amounts of the metal phase, primarily iron and its alloys with nickel and cobalt, reported from magmatic rocks of various compositions and origins.

Геохимия. 2019;64(10):1015-1025
pages 1015-1025 views

The role of garnetization of olivine in olivine-diopside-jadeite system in the ultramafic-mafic evolution of the upper-mantle magmatism (experiment at 6 GPa).

Litvin Y.A., Kuzyura A.V., Limanov E.B.


Peritectic mechanisms, controlling fractional ultrabasic-basic evolution of the upper mantle magmatism and genesis of the peridotite−pyroxenite−eclogite rock series, are substantiated in theory and experiment. Melting phase relations of a differentiated mantle material are studied with polythhermal section method in the multicomponent olivine−clinopyroxene/omphacite−corundum−coesite system with boundary compositions duplicated these of peridotitic and eclogitic minerals. The peritectic reaction of orthopyroxene and melt with formation of clinopyroxene (the “opthopyroxene clinopyroxenization” reaction) has been determined at a liquidus surface of the ultrabasic olivine−orthopyroxene−clinopyroxene−garnet system. As a result of the reaction the temperature-regressive univariant curve olivine + clinopyroxene + garnet + melt is formed. A further evolution of magmatism has experimentally studied at 6 GPa in the ultrabasic-basic olivine−diopside−jadeite−garnet system with changeable compositions of the diopside−jadeite solid solutions (controlling the clinopyroxene ↔ omphacite mineralogy). Peritectic reaction of olivine and melt with formation of garnet was established on the liquidus surface of the ternary olivine−diopside−jadeite system as the mechanism of “olivine garnetization” and going to the univariant curve omphacite−garnet−melt with formation of bimineral eclogites. Structure of the liquidus surface for the olivine−diopside−jadeite−garnet system is inferred, and its role as a “physic-chemical bridge” between ultrabasic olivine−bearing peridotite−pyroxenitic and basic silica-saturated eclogitic compositions of the garnet−peridotite facies matter. The new experimental physic-chemical results reveal the genetic links between ultrabasic and basic rocks as well as mechanisms of the uninterrupted fractional magmatic evolution and petrogenesis from the olivine−bearing peridotite−pyroxenitic to silica-saturated eclogite-grospyditicrocks. This provides an explanation for the uninterrupted composition trends for rock-forming components in clinopyroxenes and garnets of the differentiated rocks of the garnet−peridotite facieis.

Геохимия. 2019;64(10):1026-1046
pages 1026-1046 views

Synthesis of minerals and polymineral matrixes for immobilization of radioactive wastes elements

Kotelnikov A.R., Akhmedzhanova G.M., Suk N.I., Martynov K.V., Gavlina O.T., Suvorova V.A.


For the development of methods for the disposal of radioactive waste in the rocks of the earth’s crust, the concept of phase and chemical correspondence in the system of matrix material ― host rock has been proposed. This principle allows directional synthesis of certain mineral matrices. Matrix materials were experimentally synthesized ― solid solutions of minerals for immobilization of alkaline, alkaline-earth, rare-earth elements ― radionuclides. The properties of a number of solid solutions of minerals are investigated. The possibilities of processing graphite into stable matrices are studied. Methods of fixation and separation of noble metals (components of radioactive waste) and halides (Br, I) have been developed. The problems of processing glass matrix minerals (borosilicate and aluminophosphate glasses) into stable crystalline matrix materials are considered. Methods for processing glass matrices into mineral matrix materials are presented.

Геохимия. 2019;64(10):1047-1063
pages 1047-1063 views

Experimental study of the stability and synthesis of the tourmaline supergroup minerals

Setkova T.V., Balitsky V.S., Shapovalov Y.B.


Tourmaline is one of the most widespread minerals in nature and one of the most popular gems and promising piezoelectric material. The growth of large crystals is today a topical task. With the growth of tourmaline single crystals appears problems associated with its complex chemical composition, high chemical stability in hydrothermal solutions and a low growth rate. The paper reviews of recent work on the tourmaline synthesis and the results obtained in IEM RAS.

Геохимия. 2019;64(10):1064-1078
pages 1064-1078 views

Hydrothermal synthesis of gallium epidote—analogue phases Ca2Al2Ga (Si3O12) (OH) from Tykotlova gold-sulfide occurence

Kovalskaya T.N., Varlamov D.A., Kotelnikov A.R., Chukanov N.V., Kalinin G.M.


In order to reconstruct the crystallization conditions of the gallium epidote analogue Ca2Al2Ga(Si3O12)(OH) from the Tykotlova gold-sulphide ore occurrence in the Polar Urals, for the first time, a series of epidote-gallium epidote solid solutions were synthesized. The parameters of the unit cell were calculated for these phases, and IR and Raman spectra were obtained. It was concluded that gallium is predominantly in position M3, which allows us to consider the “gallium epidote” as an independent mineral specie. Stable Ga-containing aluminosilicate and silicate phases in the Ca-Ga-Al-Fe-Si-O system were obtained as by-products of the synthesis (analogs of the grossular-andradite garnet and calcium feldspar).

Геохимия. 2019;64(10):1079-1090
pages 1079-1090 views

Adsorption of strontium on manganese oxide (δ-MnO2) at elevated temperatures: experiment and modeling

Karaseva O.N., Ivanova L.I., Lakshtanov L.Z.


Strontium adsorption has been studied by the method of acid-base potentiometric titrations at three different temperatures: 25, 50, 75°C. The effect of pH, ionic strength, sorbate/sorbent ratio, and temperature on adsorption was investigated. Experimental data were simulated using two various surface complexation models, with two different electrostatic descriptions of the interface: the constant capacitance model (CCM) and the triple-layer model (TLM). Although the both models used are able to account for the acid-base reactions and surface complexation of strontium on birnessite, we consider that the TLM is more applicable for a description of heterophaseous system H+ – ≡MnOH Sr2+. Under conditions of low ionic strength and negatively charged surface, Sr2+ ions compete with the electrolyte ions and form outer-sphere complexes along with inner-sphere complexes. Consequently, using the CCM for description of strontium adsorption data could be mathematically satisfactory, but physically senseless. The equilibrium model proposed here consists of the complexes of inner (≡MnOHSr2+, ≡MnOSr+, ≡MnOSrOH0) and outer types ([≡MnO– Sr2+]+). The corresponding intrinsic equilibrium constants of the formation of these surface complexes were calculated for 25,50, and 75°C.

Геохимия. 2019;64(10):1091-1104
pages 1091-1104 views

Short communications

Standard enthalpy of formation of selenium stannite Cu2FeSnSe4

Baranov A.V., Stolyarova T.A., Brichkina E.A., Osadchii E.G.


The calorimetric determination of the standard enthalpy of formation of Cu2FeSnSe4 selenium stannite (CITSe) was carried out for the first time. This compound in its pure form does not occur in nature, but is a promising functional material (direct-gap semiconductor) and is used in photovoltaics to create solar cells as an alternative to silicon. The standard enthalpy of Cu2FeSnSe4 formation was obtained by measuring the heat of its formation from the elements in the calorimeter according to the reaction 2Cu + Fe + Sn + 4Se → Cu2FeSnSe4. As a result, the standard enthalpy of formation is detrmined: ∆fH0298.15K(Cu2FeSnSe4) = −(254.11 ± 3.96) kJ/mol.

Геохимия. 2019;64(10):1105-1108
pages 1105-1108 views

This website uses cookies

You consent to our cookies if you continue to use our website.

About Cookies