| Laboratory of metamorphic and metasomatic formations |
| Headed by Dr. Oleg V. Avchenko |
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| The laboratory was organized in 1968 on the basis of the laboratory of petrography. From 1968 to 1996, the chief of the laboratory was Dr. Mikhail Afanasyevich Mishkin. At present, Dr. Oleg Viktorovich Avchenko is the head of the laboratory. The objects of investigations are mineral deposits of the Far East and East Siberia (Yakutiya, Chukotka, Kamchatka, Primorye). We also study the rocks dredged from the floor of the Japan, Philippine, and Okhotsk Seas, as well as the Pacific Ocean. Scientific workers of the laboratory have walked many hundreds of kilometers, written about three hundreds of articles and fifteen monographs. The laboratory has a large collection of samples of metamorphic, metasomatic, and granitoid rocks of the Far East. |
| Research Interests: |
| Fluidal regime, petrology, mineralogy, and metallogenic specialization of metamorphic rocks of median masses and fold areas of the Far East. Synmagmatic metamorphism and metasomatosis in the Phanerozoic structures. Petrology of hydrothermal formations and near-ore metasomatosis. Petrology, petrochemistry, and fluidal regime of granitoid rocks. Physicochemical modelling of metamorphic and metasomatic processes. Geochemical evolution of the early crust of the south Aldan Shield. |
| Scientific staff of the laboratory: |
| O.V. Avchenko - Chief - metamorphism, petrology, mineralogy of metamorphic complexes, computer physico-chemical modelling of metamorphic and metasomatic processes M.A. Mishkin - Main scientist - metamorphism, petrology, mineralogy and geochemistry of metamorphic complexes I.A. Tararin- Main scientist - metamorphism, petrology, mineralogy, and geochemistry of metamorphic complexes of island arcs, marginal-sea and ocean floor V.O. Khudolozhkin - Senior scientist, physico-chemical methods of investigations, X-ray - sructural analysis, electrochemistry G.A. Valuy - Senior scientist - petrology, mineralogy, and fluidal regime of granitoids Z.G. Badredinov - Senior scientist - metamorphism, petrology, mineralogy, and geochemistry of metamorphic complexes of island arcs, marginal-sea and ocean floor S.N. Lavrik - Scientist - metamorphism, petrology, mineralogy, and geochemistry of metamorphic complexes |
| Principal achievments: |
| a) Characteristics of thermodynamic regime of the Pre-Cambrian and Phanerozoic metamorphic complexes formation in the continent-ocean transition zone have been revealed. |
| It has ben established that Early Archean granulitic metamorphism of ancient structures of the East Asia (south Aldan Shield, Okhotsk and Omolon massifs) occurred within the wide temperature (650-1000C) and pressure (3 - 13 kbar) intervals. |
| It was first noted that the maximum pressure on the solid phase of the Archean granulitic metamorphism is lower than that of the Phanerozoic fold belts. Specificity of the ancient Archean metamorphism is higher temperatures on the same depth relative to conditions of younger metamorphism. Fluidal regime of the Archean granulitic complexes is characterized by low partial pressure of water in a fluid over all stages of metamorphic evolution. The final (regressive) stages of granulitic metamorphism are characterized by increasing activity of CO2 with formation of reactional structures and kelyphitic rims. Carbon isotope composition of graphites from the granulitic, metamorphosed sedimentary rocks evidences a mixed, carbonic-acid fluid of mantle-biogenic origin. |
| b) In the modern island-arc systems of the West Pacific, there were established multi-stage metamorphic transformations of initial rocks caused by change of geotectonic regime of mineral formation. It was shown that glaucophane-schist metamorphism is most common in subduction-related settings, however its P-T conditions can vary from greenschist to eclogite-glaucophane-schist facies. |
| c) It was defined that all diversity of hydrothermally altered rocks may be divided into four types that depend on thermodynamic parameters controlling mineral and chemical transformations. To describe the altered rocks, we propose three independent systems of mineral facies: proper metamorphic - reflecting temperature and pressure influence; submetamorphic - characterizing a range and level of chemical activity of quite mobile components; and metasomatic - showing the behaviour of rock-forming components turned into mobile state. |
| d) We have summarized the data on manganese mineralization in ore deposits of the East Russia. The types of hydrothermal ore deposits containing parageneses of manganese minerals have been distinguished. Their principal characteristics have been considered, and models of their formation were proposed. Position of manganese mineralization in hydrothermal process, mechanisms of their origin, and possible sources of manganese have been shown in these models. The system of geothermometers (garnet-rhodonite, tremolite-ferroactinolite, amphibole-rhodonite) has been worked out, and the temperature regime of manganese rock crystallization in ore deposits of the East Russia has been studied. Manganese mineralogy and parageneses of manganese minerals of gold-silver, silver-lead-zinc, and tin-polymetallic deposits, as well as hydrothermally altered, primarily sedimentary manganese ores have been discussed in detail. Some rare minerals of manganese (pyrosmalite, pyroxmangite, tin-bearing spessartine, and others) have been described. |
| e) Petrological study of granitoid magmatism of one of the most important ore districts in Primorye - Dalnegorsk - has been completed. Thermodynamic parameters of melting and crystallization of granitoid massifs of the Dalnedorsk district have been determined. |
| f) Formula of welding electrode coatings based on ilmenite, sphene, and perovskite from the Primorye deposits has been applied in industry. |
| g) A program of calculation of chemical and mineralogical composition of solid and gas components of combustion products of the Far East coals has been proposed. |
| Additional information: |
| The researchers of the Laboratory can organize joint investigations with foreign scientists who is interested in studying the problems listed above. |
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| Contact: |
| Far East Geological Institute |
| 159, Prospect 100 let Vladivostoka, |
| Vladivostok, 690022, Russia |
| E-mail: olegavchenko@yahoo.com |
| Phone:(7)4232 312960 |
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