The Salma subduction eclogites of the Meso-Neoarchean Belomorian Eclogite Province have compositions of N-MORB oceanic crust protoliths and contain felsic veins of plagiogranite compositions. Felsic veins consist of metamorphic minerals sush as garnet, quartz and kyanite, the earliest high-pressure inclusion of phengite and zoisite in garnet. Veins have geochemistry characteristics that are typical for island arc granites or adakites. They are compositionally comparable with eclogite-bearing tonalite-trondhjemite-granodiorite (TTG) gneisses, modern adakite, and Archaean andesite association of the Vedlozero-Segozero greenstone belt. The origin of these felsic veins can be represented as a product of melting of fluid-modified oceanic mafic slab at PT-conditions of eclogite metamorphism.Geothermometry and pseudosection calculations of metamorphic conditions in felsic veins, for eclogitic mineral assemblage of pyropic garnet, kyanite, high-silica phengite and quartz gave high pressures conditions (ca. 16-22 kbar) at relatively low temperatures (ca. 600-650 degrees C); for secondary decompression plagioclase +/- biotite coronas between quartz, kyanite and garnet gave 14-11 kbar at 650-700 degrees C. This estimate corresponds "warm" subduction, which is most consistent with the parameters of the modern subduction of the base of the Cascadia plate . Mineral assemblages in eclogites, that included the felsic veins, give 15-11 kbar at 750-700 degrees C. Thermodynamic modelling indicates that the eclogites hosting the felsic veins did not reach partial melting conditions under the estimated PT conditions: exposure temperatures to the mafic rocks must have been significantly higher. A probable explanation for high-pressure parageneses in felsic veins may be the formation of plagiogranites as a result of the melting of the mafic slab under higher temperature and pressure conditions than were measured in this work. Thus, the high-pressure paragenesis of garnet, phengite, zoisite, and kyanite reflects the path of rock exhumation through eclogitic conditions.Zircon from the felsic veins gave several Archean and Paleoproterozoic ages similar to 2.87, 2.78, similar to 2.70 and, similar to 1.9 Ga. The oldest age gave the fluid-modified oceanic zircon (similar to 2.9 Ga) from Fe-Ti eclogites directly near the veins. The oldest igneous zircons in the veins are represented by a population with the age of similar to 2.87 Ga and correspond to the igneous age of some TTG gneisses, which do not contradict a hypothesis of the plagiogranite formation during the melting of the mafic slab in the subduction zone. A Neoarchean zircon population of similar to 2.78 Ga is often present in eclogitized mafic rocks and surrounding TTG gneisses which can be associated both with the formation of TTG gneiss protoliths in the subduction zone (?) and with the recrystallization of older zircon as a result of fluid or thermal impact. The epsilon Hf of the older population (similar to 2.87 Ga) is + 3 to + 4, indicating a juvenile origin; the similar to 2.78 Ga population has similar Hf-isotope compositions, suggesting that their ages reflect resetting (non-zero Pb loss) of the older zircons. The Sm-Nd model T-DM ages of Grt-Ky veins have Meso-Neoarchean values (3.0-2.75 Ga) with positive epsilon Nd = 1.8-3.8 that may indicate a juvenile nature of sources of the plagiogranite melt. The eclogitized rocks of the Belomorian province generally underwent the granulite facies overprint at similar to 2.74-2.64 Ga ago that is coincides with the age of granulite facies metamorphism of regional and global rank. The Paleoproterozoic evolution of the Salma eclogites and the East European Craton as a whole: at 2.5-2.4 Ga and 2.0-1.9 Ga with formation of the Lapland-Mid-Russia-South Baltia intracontinental and Svecofennian accretionary orogens was terminated in Paleoproterozoic time at similar to 1.87-1.7 Ga. These age values correspond to closure of Pb-Pb and Sm-Nd isotopic systems of rock-forming metamorphic minerals of the felsic veins.

The paper presents data on the formation of K–Na richterite in the enstatite + diopside association with K2CO3–Na2CO3–CO2–H2O fluid at 3 GPa and 1000°C as a model for the formation of this mineral in peridotites of the upper mantle. Richterite formation depends on the (H2O + CO2)/(K2CO3 + Na2CO3) and K2CO3/Na2CO3 ratios in the starting material. A high concentration of alkaline components in the fluid leads to the decomposition of clinopyroxene, the formation of olivine, and a change in the component composition of the pyroxene and amphibole. Fluids with a high potassium concentration are favorable for the formation of K-richterite similar in composition to that formed in metasomatized peridotites of the upper mantle. In some cases, such a fluid leads to the decomposition of amphibole and stabilization of alkaline melt. An increase in the activity of the sodium component results in richterite similar in composition to richterite from lamproites. The clarified relations can be used to assess the activities of fluid components and conditions for the formation of K-richterite. To update the data bank of the Raman spectra of minerals, the largest and most homogeneous amphibole crystals of different compositions were studied.

Методом лазерной абляции с индуктивно связанной плазмой было проведено U-Th-­Pb изотопное датирование магматических и метаморфических цирконов, извлеченных из эгирин-­содержащих гнейсов в Гридинском меланже Беломорской эклогитовой провинции. Магматические ядра с возрастом 2,89–2,83 млрд лет датируют протолиты. Метаморфические зерна и каймы дали диапазон возрастов 2,80–1,8 млрд лет с пиками ~2,80, 2,75, 2,70 и 1,8 млрд лет, отвечающими последовательности тектонометаморфических событий в регионе. Наряду с типичным цирконом обнаружены зерна с необычными гетерогенными ядрами, в строении которых сочетаются гранулярные, везикулярные и вермикулярные текстуры. В них, по данным спектроскопии комбинационного рассеяния, наблюдаются преобразования от кристаллического до аморфного состояния. Микрогранулированные цирконы интерпретируются как свидетельства мезоархейского импактного события примерно 2,87 млрд лет или древнее.

Впервые инструментальными методами трехмерной электронной микроскопии, флу- оресцентной микроскопии и спектроскопии комбинационного рассеяния исследо- вано эндогенное органическое вещество в эклогитах Салмы (Беломорская эклогито- вая провинция на Балтийском щите). Установлены два типа вещества, одно из которых имеет явные признаки биогенного происхождения (бактерии, бактериальная целлюлоза). Экспонирование образца в герметичном контейнере с химическим маркером (спиртовой раствор пентабората цезия Cs[B5O7(OH)2] · 0.5H2O) в условиях переменного температурного режима (600 циклов нагрева / охлаждения) показало, что раствор цезия способен проникать вглубь образца через естественные коллекторы, сообщающиеся с поверхностью. Результаты маркирования скрытых микроколлекторов позволяют дифференцировать наложенные биогенные формы органического вещества, не связан ные с петрологической эволюцией эклогитов, от «первичных» эндогенных включений. В микровключениях органического вещества, в которых отсутствуют морфологические признаки бактериальной природы, обогащение цезием ниже предела обнаружения энергодисперсионного детектора в режиме пониженного вакуума сканирующего электронного микроскопа. Предположительно такие формы сингенетичны с эклогитами.

The paper summarizes authors' earlier and newly obtained experimental data on the formation of phlogopite and chromium-bearing potassium titanates of the crichtonite, magnetoplumbite, and hollandite groups, which are indicator minerals that characterize various stages of modal metasomatism in the upper mantle. Phlogopite-forming reactions were studied in the garnet–orthopyroxene system in the presence of H2O–KCl fluid at 3 and 5 GPa and 900–1000°C as simulating phlogopite formation in garnet peridotites and pyroxenites. Experiments have demonstrated regular variations in Ca and Cr contents in the garnet and Al in the pyroxenes, as well as the composition of the newly formed phlogopite, depending on the concentration of the potassium component (KCl or K2CO3) of the fluid. Experiments on the formation of potassium titanates (yimengite, mathiasite, and priderite) in the chromite–rutile/ilmenite–K2CO3–H2O–CO2 system at 3.5 and 5 GPa and 1200°C have proved that these minerals can be formed when chromite reacts with potassic aqueous–carbonic fluid, but these reactions require additional sources of titanium. These sources may be rutile and/or ilmenite, which are usually also produced by modal metasomatism of peridotites. The experiments thus confirm that the formation of titanates marks the most advanced stages of metasomatism in mantle peridotites. The experiments have shown that the formation of potassium titanates follows the formation of phlogopite, whereas assemblages of the titanates with phlogopite are produced at higher concentrations of the potassium component of the fluid than phlogopite alone. The relationships between the titanates are also a function of the activity of the potassium component in the fluid and, probably, pressure. The relationships and trends reproduced in the experiments clearly illustrate features of mineral assemblages and variations in compositions of minerals from metasomatized peridotites in the lithospheric mantle.

A potentially new mineral, M2Na-dominant analogue of eudialyte from the Khibiny alkaline massif, was investigated using the methods of electron probe microanalysis, X-ray diffraction, and IR spectroscopy. The crystal structure was refined to R = 5.7% in the anisotropic approximation of atomic displacements using 2577 independent reflections with F > 3(F). The unit-cell parameters are: a = 14.277(1), c = 30.400(1) Å, V = 5328.7(1) Å3; the space group is R-3m. The idealized formula of the mineral is (Z = 3): Na14Ca6Zr3[Na2(Fe,Mn)][Si26O72](OH)2(H2O1.0Cl0.6S2-0.5)(OH,H2O)2.5. Distribution of cations in the M2 micro-region is established: Fe in the flat-square coordination, Mn in the square pyramid and Na in the seven-vertex polyhedron. A comparative analysis of crystal chemical features of eudialyte М2Na-analogue samples from the Khibiny-Lovozero alkaline complex and Ilimaussaq alkaline pluton, Greenland is given. The mechanism of blocky isomorphism with the replacement of IVFe2+ with VIINa in the M2 micro-region is discussed. IR spectra of the М2Na-dominant eudialyte analogue are given: essentially hydrated sample (Na,H3O,H2O)15Ca6Zr3[Na2Fe][Si26O72](OH)2Cl∙2H2O from Ilimaussaq, less hydrated М2Zr-bearing sample (Na,H3O)13(Ca4Mn2)Zr3(Na2Zr)[Si26O72](OH)2Cl∙H2O from Lovozero and low-hydrated sample Na14Ca6Zr3[Na2(Fe,Mn)][Si26O72](OH)2Cl(OH,H2O)3 from Khibiny studied in this work.

The Salma-type Archaean eclogites exposed along the northwestern boundary of the Belomorian Eclogite Province in the eastern Fennoscandian Shield formed as a result of the Mesoarchaean-Neoarchaean subduction and collision. The common protoliths of the Salma-type subduction-related eclogites were oceanic layered gabbro and volcanic-sedimentary assemblage. The eclogite-facies pillow lavas and associated alumina-siliceous sediments that fill interpillow space and intercalate with lava flows are the main objects of our work. The kyanite-garnet-phengite-quartz rocks formed after alumina-siliceous sediments contain fluid inclusions trapped in large relic quartz grains. The fluid inclusions yielded an isochore that corresponds to PT-conditions of a beginning of the Salma oceanic rock subduction from the seafloor level that generally confirms the sedimentary provenance of these rocks. The alumina-siliceous sediments underwent the eclogite-facies metamorphism at pressure no lower than 21 kbar and temperatures of 650-750 degrees C and transformed into kyanite-garnet-phengite-quartz rocks. During exhumation under granulite-facies conditions at temperatures up to 900 degrees C and pressure down to 9 kbar, eclogite facies metasediments underwent partial melting accompanied by disequilibrium breakdown of phengite + quartz association with formation complex polymineralic pseudomorphs consisting of feldspars, biotite, muscovite, kyanite, corundum, and dumortierite. U-Pb dating of Th-rich igneous zircon from melted metasedimentary and mafic rocks using the LA-ICP-MS and TIMS methods yielded the time of granulite facies event accompanied by partial melting processes at similar to 2.45 Ga. After this, zircon underwent fluid-induced alteration, causing partial dissolution followed by precipitation of new Th-poor zircon and zircon rims around ancient grains at similar to 1.9 Ga ago

An intermediate member of the eudialyte–sergevanite solid-solution series has been investigated by X-ray diffraction analysis, electron probe microanalysis, and IR spectroscopy. The trigonal unit-cell parameters of the mineral are found to be a = 14.1944(4) Å, c = 30.294(1) Å, and V = 5286.0(3) Å3; sp. gr. R3. The crystal structure is refined to the final reliability factor R = 4.48% in the anisotropic approximation of atomic displacements, using 2420 reflections with F > 3σ(F). The idealized formula of the mineral (Z = 3) is Na14Sr(Ca3Mn3)(Na2Fe)Zr3Si26O72(OH)3Cl · H2O. An increase in the Ca and Fe contents in comparison with the holotype sergevanite does not increase symmetry. The problems of genesis of calcium-poor minerals with eudialyte-type structure are discussed.

The results of experimental studies are presented for reactions in the orthopyroxene–garnet–phlogopite system in the presence of H2O–KCl fluid at 3–5 GPa and 900–1000°C, which model the processes of phlogopite formation in garnet peridotites and pyroxenites during alkaline metasomatism of the upper mantle. The experiments demonstrated regular variations in the composition of garnet, pyroxenes, and phlogopite depending on the KCl content of the fluid. With increasing KCl content of the fluid, enstatite and garnet become unstable, the Al2O3 content of enstatite decreases, and the amount of grossular and knorringite components in garnet are maximum at a KCl content of ~10 mol %. Our results illustrate well the regular variations in the compositions of the coexisting minerals and their zoning in phlogopite-bearing peridotites of the lithospheric mantle.

Processes and products of ion exchange of günterblassite (K,Ca,Ba,Na)3–xFe1–y[(Si,Al)13O25(OH,O)4]·7H2O (microporous silicate, structurally intermediate between smectites and zeolites) and three samples of zeolite gmelinite (Na,K,Ca,Mg)x[(Si,Al)12O24)·nH2O of different composition with cations of various metals were studied. It was shown that günterblassite exhibits high activity and sorption capacity with respect to Rb+, Cs+, Ag+ cations and, to a lesser extent, Pb2+ and Ba2+: even at room temperature for 1 h, the concentration of M2O (M = Rb, Cs, Ag) in the sorbent reaches 10–13 wt %. The ion exchange in gmelinite occurs according to the frontal mechanism, propagating from the periphery of the crystal to its center. In reactions with Pb2+, the activity of gmelinite increases with a rise in its sodium content and decreases with a rise in potassium content. The crystal structure of Pb-substituted gmelinite was studied and it was shown that Pb2+ ions populate both zeolite channels. Synthetic gmelinite obtained from cheap natural raw materials and fly ash from thermal power plants can be used to purify water from lead.

Изучены Fe-­Ti-эклогиты в проявлении горы Куропачья. Геохимия главных и рассеянных элементов показывает их сходство с эклогитами Салмы Беломорской провинции в целом и имеют геохимические признаки толеитов СОХ. В связи с этим предлагается механизм океанской субдукции и ультравысокобарического метаморфизма при формировании пород. Для определения возраста Fe-­Ti-эклогитов с помощью LA-ICP-MS проведено исследование Th-­U-Pb изотопной системы в цирконах. Для планирования датирования и интерпретации полученных возрастов цирконы исследовали с помощью современных методов – оптическая и электронная микроскопия, микрозондовый анализ, трехмерная лазерная микроскопия, черно-­белая (SEM-CL) и цветная (EPMA-CL (tc)) катодолюминесценция, спектроскопия комбинационного рассеяния. Цирконы имеют зональное строение – ядра с высокими и оболочки с очень низкими содержаниями урана и тория. В ядрах архейского возраста сохраняется осцилляторная магматическая зональность и отсутствуют микроскопические признаки метамиктизации. В оболочках протерозойского возраста наблюдается катодолюминесцентная неоднородность, причины которой – кристаллохимические факторы во время единого этапа кристаллизации и механические напряжения.

New layered organic conductors, (BEDT-TTF)4(BiCl5)1 7 ( 1 ), δ-(BEDT-TTF)2BiCl5 ( 2 ), and δ-(BEDT-TTF)6Sb3Cl12 ( 3 ), were obtained (BEDT-TTF is bis(ethylenedithio)tetrathia-fulvalene). In the crystal structures of 1 — 3 , organic radical cation layers are composed of di-merized stacks. The dimers are formed by BEDT-TTF radical cations rotated through angle ω relative to each other, which results in twisted stacks, giving rise to so-called twisted overlap mode in the layers. These layers alternate with non-conductive inorganic layers consisting of chains in which the Cl, Bi, and Sb sites are partially occupied. This indicates discontinuities in the chains of anions, and, apparently, the absence of continuous polymer chains in the crystal structure. According to measurements of the temperature dependence of the electrical resistance, the compounds are semiconductors.

Синтезированы алюмосиликаты с канкринитовой структурой, по составу отвечающие высококремниевой разновидности канкрисилита и CO 3 — дефицитному аналогу канкринита. Эмпирические формулы полученных соединений — Na 6.1 3 [Al 4.36 Si 7.64 O 24 ](CO 3 ) 0.91 · 2.85H 2 O и Na 6.19 [Al 5.53 Si 6.47 O 24 ](CO 3 ) 0.37 · 3.92H 2 O соответственно. Оба образца охарактеризованы методами ИК-спектроскопии и порошковой рентгенографии. Обсуждаются условия образования канкрисилита и карбонат-дефицитного канкринита в природе. Сделан вывод о том, что кристаллизации канкрисилита способствуют надкритические условия и ультраагпаитовая обстановка.