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Volkova S.A.,Central Research Institute of Geology of Nonmetalliferous Mineral Resources | Il'icheva O.M.,Central Research Institute of Geology of Nonmetalliferous Mineral Resources | Kuznetsov O.B.,Central Research Institute of Geology of Nonmetalliferous Mineral Resources
Lithology and Mineral Resources | Year: 2011

Graphite-bearing rocks and graphites from the Precambrian metamorphic sequence of the Pestpaksha ore occurrence, Murmansk district, have been studied by the X-ray method. It was determined that the rocks have a complex polycomponent composition. Graphite is associated with garnet-quartz, pyroxene-amphibole, and biotite-quartz with an admixture of pyrrhotite, kyanite, chlorite, and other minerals. In terms of mineral composition, the studied samples are subdivided into five groups. The structural characteristics of graphite-parameters a 0 and c 0, the degree of structural perfection (U), the content of rhombohedral phase (R), and others-were found to be different for each group. The U value varies from 1.04 to 1.56 (with predominant values from 1.4 to 1.5), while the content of rhombohedral phase in samples is no more than 18%. This fact indicates a relatively high 3D order, which is typical of graphites from metamorphic rocks. Graphites from metasomatites have the lowest U value, while those from weathering zones are characterized by a small value of the coherent scattering domain (CSD). It was established that interplanar spacing d 002 of graphite correlates with depth, while the degree of ductility and flexibility of the graphite is defined by conditions of its retrograde metamorphism. © 2011 Pleiades Publishing, Ltd.

Giniyatullin K.G.,Kazan Federal University | Shinkarev Jr. A.A.,Central Research Institute of Geology of Nonmetalliferous Mineral Resources | Shinkarev A.A.,Kazan Federal University | Krinari G.A.,Kazan Federal University | And 4 more authors.
Eurasian Soil Science | Year: 2012

The relationship between the fixation of organic matter into a form resistant to oxidative destruction and the actual structure of the clay component was studied in profiles of different-aged chernozemic soils of a filled fortification in the Volga Bulgaria. With the use of modern methods (X-ray phase analysis, laser diffraction granulometry, hyphenated thermal analysis-FT-IR spectroscopy, adsorption-luminescence analysis, and ICP emission spectroscopy), it was shown that the formation of organic-smectite complexes with a disordered c*-axis structure is a universal and usual way for the kinetic stabilization of the system during pedogenesis under forest-steppe conditions. The main aim of the study was to experimentally substantiate this phenomenon. © 2012 Pleiades Publishing, Ltd.

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