REVIEWS
Institute of Experimental Mineralogy, Russian Ac.Sc. works in the area of "Physical-chemical problems of the processes of minerals, rocks, and ores formation in the Earth's crust and mantle as a basis for forecast and search for mineral deposits". The research works are mainly fundamental and are involved in 10 fundamental, one applied, and one search topics. The theoretical and experimental results obtained allow new approaches to the study of substantial composition of the Earth's interior, make it possible to search for the mineral deposits and contribute to the development of fundamental Earth sciences. Results of these investigations are reported in scientific periodicals as well as in the year- and five year-books of the IEM RAS. However, these issues are not available for a wide circle of foreign scientists and the idea arose to publish a special issue of the journal "Experiment in Geosciences" with brief information in English on the major research results obtained in the last important for the experimental investigations period. The edition of such type issues (Experiment-89, Informative volume. Ed. V.A. Zharikov and V.V. Fed'kin. Moscow, Nauka Publisher, 1990, 129 p.) showed them very popular among the experts in geological sciences.
This issue presents the results of experimental and theoretical investigations in the field of mineralogy, petrology, geochemistry, as well as some new directions such as radioecology, synthesis and modification of minerals for the period of 1991-1995. Given in the end of the issue is the list of papers, books, collected papers, theses, and patents for this period. Naturally, when working on the issue, some data were refined and complemented with new results. These changes are reflected in some papers published in 1996-1997 which are also involved in the list given, however they do not cover all the results of these years.
The authors and editors of the issue hope that the materials presented which reflect the major results and scientific interests of the Institute of Experimental Mineralogy RAS will be of use for a wide circle of scientists-geologists, professors and students of geological departments.
Chief editors of the issue:
Directorof the IEM RAS academician V.A. Zharikov
Scientific secretary Dr. V.V.Fed'kin
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Priority research directions
in geochemical sciences
Zharikov V.A.
The current state of Russian Science and all over the world dictates the choice of the primary directions of research. The following priorities can be defined on the basis of the analysis of the current state of the Earth sciences (geochemistry, petrology, mineralogy, lithology, ore deposits doctrine, crystal chemistry etc.).
The multidiscipline approach and using experimental and theoretical (computer) modelling methods turned out to be most efficient.
Reference:
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Experimental and theoretical research
at the Institute of Experimental Mineralogy in 1991-1995.
Zharikov V.A., Fed'kin V.V.
In 1991-1995 the Institute of Experimental Mineralogy RAS continued the basic research on the "Physical-chemical problems of the processes of formation of minerals, rocks, and ores in the Earth's crust and mantle as a basis for the forecast and search for mineral deposits" in line with the recommendations of the geology, geophysics, geochemistry, and mining department of the RAS about the research priorities in the Earth sciences [1]. As the experiments in the Earth's sciences are particular and new qualitative data are needed for the solution of the most topical problems in geology, the predominant line of research in this period was:
Special emphasis in the study of magmatic systems was given to the investigation of generation and evolution of primary magmatic melts in the Earth's crust and mantle. Experimental study on the melting of starting substrate of basic composition was carried out in a wide pressure range from crust conditions-melting of amphibolite with natural content of volatile components (V.A. Zharikov and L.I. Khodorevskaya) to the conditions of fusion of mantle primary melts in the base mantle system of the spinel- and garnet-lherzolite composition (Yu.A. Litvin). Phase equilibria of minerals and primary magmas have been studied in both systems.
Original research on the rheological properties of albite, zhadeite, and diopside melts in dry system as well as water containing diopside melt was performed at PH2O to 5 kbar (E.S.Persikov and P.G. Bukhtiyarov). A wide scope of experimental data on rheological properties of silicate melts allows to give forecast estimations of viscosity in the pressure range up to 240 kbar.
Emphasis was also placed on the investigations of the solubility and forms of water and hydrogen presence in the melts of different composition: in zhadeite and albite melts at Pfl to 5 kbar, Plith to 70 kbar (E.S. Persikov, P.G. Bukhtiyarov) in the albite melt with different mole fractions of H2O and H2 (Bezmen et al.), and in acid glasses of rheolite and quartz composition (T.P. Salova, T.A. Stolyarova, M.B. Epelbaum).
A detailed analysis of the problems of granitization and formation of magmas of acid compositions is given in the review of V.A. Zharikov, M.B. Epelbaum. Some theoretical aspects of this problem (interaction of water-bearing acid magmas with basalt chamber, calculation of the melting rate of granite substrate with account of convection, dynamics of the magmatic chamber crystallization etc.) are considered in the papers of M.B.Epelbaum and A.G. Simakin and A.G. Simakin.
A great deal of experimental and theoretical data on the fluid magmatic interaction of melts stimulated research on the development of the model of Earth origin. Original (ñomet) hypothesis of the Earth origin with the key concept of its two stage evolution is based on the numerous experiments on liquid layering of magmatic melts under the effect of reduced fluids emphasizing their important part in the development of the natural magmatic systems (A.A. Marakushev).
The problem of metamorphism and geodynamics covers a wide range of topics from the global geo-
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dynamic formations to specific experimental problems on the distribution of isomorphic and impurity components in individual phases and assemblages. Experimental study of mineral equilibria with the participation of phases of variable composition was carried out using the conventional methods designed in the Institute [2]. New data were obtained in the charnokite assemblage (A.A. Graphchikov, A.N. Konilov), in staurolite-granate paragenesis (V.V. Fed'kin, L.Yu. Yakovleva; L.Yu. Zharikova), in the system hemoilmenite-rutile (A.N. Konilov). The fascinating experimental results on the migration velocity of fluid inclusions in quartz in thermo- and stress- gradient conditions were obtained by K.I. Shmulovich and I.A. Zonova as well as data on isotope equilibria of U and Pb in zircons (N.I. Bezmen). It is shown that geochemical behavior of U and Pb in the metamorphic processes differs essentially and is governed by the acid-basic properties of the solution.
Based on experimental data the following mineralogical sensors were derived: geothermometers, geobarometers, indexes of volatile components activity which are widely used in the qualitative estimation of physical-chemical conditions of metamorphism, their evolution in time and space. The results of these investigations are given in the papers by V.I. Fonarev with co-authors, T.V. Gerya and L.L. Perchuk, V.V. Fed'kin with co-authors, V.V. Fed'kin. Detailed structural-petrological study of the certain metamorphic complexes, qualitative characteristics of the evolution of mineral formation parameters suggested the geodynamic models of the evolution of individual regions (V.I. Fonarev et al. concerned with Lapland granulites, L.L. Perchuk, T.V. Gerya and O.G. Safonov on the processes of charnokitization). The research was based on the natural objects with computer-based simulation of the respective processes with account of qualitative data on geothermodynamic and physical properties of minerals and rocks (L.L.Perchuk, Yu.Yu. Podladchikov).
The investigation of physical-chemical models of endogene ore deposits formation is tightly related to the problems of metasomatism, prompted the development of the physical-chemical model of the formation of a concrete type of ore deposit - the W-Mo greisen deposit of Akhchatau in the Central Kazakhstan. The perennial investigations on the above problem are reported in many papers ( see the list of publications of the IEM RAS) and summarized in the paper by V.A. Zharikov, G.P. Zaraisky.
Experimental research embraces different aspects of the problem, primarily, the study of mineral equilibria in fluoride systems - the most aggressive and geochemically important for the transfer of ore components at the greisen formation. The effect of acid fluoride solutions on the geochemical behavior of silicon, aluminum, tungsten has been studied (G.P. Zaraisky, Yu.B. Soboleva), as well as solubility of tungstenite and corundum in fluoride solutions (G.P. Zaraisky), cassiterite and uranium oxides in boron-fluoride, chloride and other solutions (A.F. Redkin), the experimental data were obtained on the fluorine distribution between phlogopite and fluid at elevated parameters of mineral formation (A.M. Aksyuk).
The equilibrium ferberite-sheelite was studied in chloride solutions (V.S. Korzhinskaya, G.P. Zaraisky, V.N. Balashov), experiments on the gain and loss of base metals (Cu, Pb, Zn) were carried out under the conditions of the interaction of the leucocratic Akhchatau granite with solutions of different composition (G.P. Zaraisky, F.M. Stoyanovskaya), the diagrams on the solubility in the end system Al2O3-SiO2-H2O-HCl 9 in pure water and 10m solution at T=200-400oC and P=1 kbar (I.P. Ivanov) were plotted.
Distribution of ore components in the systems granite-water salt fluid, or salt melt determines, to a great extent, the trend of ore generation processes and experimental study of this effect is of prime importance. The research was undertaken in the system granite-fluorine-bearing fluid (distribution of W, Ta, Nb and Sp); distribution of rare earth's between melt silicate and salt phases forming as a result of liquid differentiation, distribution of ore metals Mo, Pb, Zn between coexisting immiscible melts: alumosilicate granite and salt fluoride ones (Yu.B. Shapovalov).
An essential growth of the distribution coefficients of rare metals (W, Mo) and base metals (Pb, Zn) between granitoid melt in the granodiorite-granite-leucogranite series and chloride- ore fluoride-bearing water fluid was found at t= 800-1000oC and P=1 and 5 kbar. Certain differences in the distribution of metals depending on pressure, melt composition, and fluid were determined.
The distribution of ore components in different fluid-magmatic systems is a major issue under the
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head "Ore systems and processes" comprising the results of experimental investigations on the distribution of rare earth elements and yttrium between basalt and lamproite melts and water-chloride solutions (V.A. Zharikov, N.S. Gorbachev). The effect of temperature and pressure on the distribution of these elements has been studied in the range T= 1100-1300oC and P=1-14 kbar. The distribution of REE and yttrium between sulfide and basalt melts, acid-basic interaction and fractionation of Eu+2 and Eu+3 differing in the endogenic processes in their acid-basic properties has been studied at a pressure of 5 kbar, experimental modelling of the crust contamination of basalt magmas at the interaction with anhydrite-dolomite-mergel rocks has been performed. Partitioning of Cl, base metals (Fe, Cu, Zn, Pb) and platinum group elements was studied in the system water-chloride fluid - basite melt (of basalt and andesite composition) (N.S. Gorbachev, L.I. Khodorevskaya).
In the system iron-sulfide melt, disintegration governs the processes of the formation of chondrites and series of sulfide deposits. Experimental results of the study on this problem and distribution of Pt and Pd between coexisting melts is discussed in the paper of Yu.B. Shapovalov. The theoretical analysis and geological interpretation of the data obtained, brought forward the hypothesis of formation of diamond-bearing rocks of the various formation types. The proposed thermodynamic model shows that in all the formation types, diamond generation is related to the magmatic systems affected by high fluid pressure and fluid-magmatic interaction (A.A. Marakushev).
A number of sulfide systems were studied using the method of high temperature electrochemical cells. The techniques were mastered of buffereing low partial CO2 pressures in the systems Me-S-O and determining thermodynamic properties of phases of stable composition and solid solutions in high temperature galvanic cells with oxygen-ion conductivity of a solid electrolyte. The theoretical analysis of the systems metal-sulfide-oxide-silicate has been performed which is necessary for the study of physical-chemical conditions of sulfide ore deposits and meteorites formation. The scope of the experimental studies on the mentioned systems by the methods of high temperature electrochemistry was defined. The electrochemical sensors for determining pH2O and aS2(gas) in high temperature gas mixtures of the system C-H-O-S were developed. pH2 were determined in the high temperature fumaroles of the volcano Kudryavy and aS2(gas) at the volcanos Papandayn and Merapi (Indonesia) (E.G. Osadchii, S.E. Lunin).
In studying the Au-As-H2O-HCl systems at 200-300oC and Ptot=50 MPa under different oxidation conditions, a new phenomenon was discovered: low temperature formation of gold-arsenic intermetallic compounds with the common formula AuxAsy where x=1-3, y=2-6 in the hydrothermal solutions in the reducing medium with hydrogen fugacity controlled in situ (V.I. Tikhomirova, G.M. Akhmedzhanova).
Experimental and theoretical research of the model hydrothermal fluid is of prime importance at the IEM RAS. V.A. Zharikov, Yu.V. Alyokhin, A.V. Plyasunov carried out the theoretical study using both geological and thermodynamic approaches to the problem. The model of concentration partitioning at the two phase filtration of the electrolyte solutions through fine-porous media was proposed, as well as the model of precipitation and adsorption capturing of the ore components-impurities upon the massive crystallization of a mineral from the gel-phase and its further recrystallyzation under hydrothermal conditions (L.Z. Lakshtanov). Acid-basic properties of the amorphous silicon and gold adsorption at its surface have been experimentally studied.
The investigations on the heterogenization of the fluid were carried out in more complex fluid-salt systems at T=400-600oC and P= 3-5 kbar. The data obtained explain the peculiarities of the composition of fluid systems at the metamorphism, the behavior and activity of its individual components (K.I. Shmulovich, N.A. Plyasunova, S.I. Tkachenko). New experimental data were obtained by M.A. Korzhinsky at the study of phase equilibria in the systems with controlled HCl activity, and a detailed study of the high temperature fumaroles of the volcano Kudryavy allowed to test and refine the models and hypotheses proposed on the natural object in natural experiment (K.I. Shmulovich, M.A. Korzhinsky, S.I. Tkachenko).
The properties of the hydrothermal fluid are to a great extent governed by the properties of its major component-water. This problem has been studied at the Institute for many years. The experimental substantiation of the fluctuation model of liquid state has been completed, phemenological thermodynamic theory of supercrytical fluid mixtures
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nonelectrolites has been developed. The enthalpy of the hydrogen bonds formation has been originally determined at T=450oC using IR absorption spectra, the major properties of subcrytical water have been studied at P=0.1-100 kbar and T=300-1000oC (Yu.E. Gorbaty, A.G. Kalinichev, G.V. Bondarenko).
The phenomenon of clasterization in compressed gases (Ar, O2, H2, CO2, H2) at the parameters to critical densities was experimentally proved and the model of its mechanism has been developed. It was experimentally shown that in all the systems mentioned the certain P and V intervals exist in which the deviation from the gas ideality could be with a good accuracy described by this model (N.G. Sretenskaya, I.V. Zakirov).
The experimental study of the system sulfur-water has been completed at T=200-440oC and P up to 500 atm. The sulfur forms dissolved in this system has been for the first time determined at the experimental conditions using the method of high temperature Raman spectroscopy, their thermodynamic functions have been calculated (V.I. Sorokin, T.P. Dadze, G.A. Kashirtseva, P.Yu. Orlov).
The problem of the utilization and burial of HAW (high active wastes) is currently one of the most actual. Experimental investigations on the development of inexpensive and stable enough to the environmental influence materials for the utilization and burial of HAW are, however, scanty and are carried out only in individual institutes. More than five year research on the problem at the IEM RAS was a notable success. Based on the comparative geochemical analysis of the compositions of liquid radioactive wastes of nuclear energetics and rocks of the natural magmatic complexes, a conception of phase and chemical correspondence of mineral matrixes-fixators of the RAW elements and rocks suitable for their long time storage has been developed. The set of the studied natural and synthetic minerals potentially useful for the burial of radionuclides has been essentially broadened, they have been synthesized and tested for the leaching rates in aggressive media (V.A. Zharikov, V.N. Zyryanov, A.P. Kotel'nikov, V.A. Suvorova et al.).
Applied investigations on the synthesis and modification of the properties of natural and synthetic minerals were bodily pointed at the solution of the problems of their practical use in engineering and economics. They imply the technique of producing quartz with phosphorus impurity pink colored upon the ionizing irradiation, the technique of growing crystals of dichromatic amethist-citrine quartz- ametrine, one of the most rare and precious varieties of colored quartz, the technique of growing monocrystal high temperature beta-quartz on seed, an industrial technique of thermodiffusion coloration of corundum (natural and synthetic) and its modification to blue saphire and green chrizoprase etc. (V.S. Balitsky).
The fundamental research in geological sciences has been carried out and new interesting data have been obtained on the physical properties of individual minerals and systems. This implies the Mossbauer investigations of the super fine structure of germanium analogs of mantle silicate phases (G.V. Novikov, L.V. Sipavina), the study of the piesoelectrical properties of signetoelectrical monocrystals (A.G. Kalinichev), the development of the method of spectral thermomagnetic analysis and the study using this method, of physical and magnetic properties of hemoilmenite (A.N. Nekrasov).
Among the most important technique and apparatuses developments in experimental mineralogy, the following works are to be noted: the X-ray spectral microanalysis of the substance (I.M. Romanenko), the study of mineral equilibria by the methods of high temperature electrochemistry (V.I. Sorokin, E.G. Osadchii, S.M. Beloborodov), information calculation system on the crystallostructural data of mineral (MINCRYST) (A.V. Chichagov et al.), super high pressure apparatuses (L.T. Chudinovskikh), apparatuses and methods for measuring oxygen and sulfur activities in high temperature fumaroles of active volcanos (E.G. Osadchii) etc.
Detailed information on the research carried out in the Institute and the results obtained are present in our journals , books, papers, and theses. The list of publications is given in the end of this issue. The authors and editors of this issue hope that this publication will be helpful for everybody who is interested in research in experimental mineralogy, physical-chemical petrology, and geochemistry.
References:
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