Biotites from rare-metal granites of Ruska-Polyana massif (Ingul megablok, the Ukranian Shield)
Authors: Zaiats O.V., Larikov A.L. Sobolev V.B., Kushnir S.V., Vyshnevskyi O.A., Syomka L.V.
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At the moment, there are few publications on the chemical composition of biotites from Ruska-Polyana rare-metal granites. We found no published data on the content of biotites trace elements Zn, Sr, Ba, Zr, Nb, Ta, Cl. The aim of our work is to study the chemical composition of biotites Ruska-Polyana rare-metal granites. Chemical composition of biotite determined using scanning electron microscope JSM-6700F, equipped energodispersive system for microanalysis JED-2300. In addition, the definition Zn, Sr, Ba, Zr, Nb, Ta, F, Cl in biotite (depth interval 239,6–242,0) was carried out on electron-probe device JXA firm Jeol 8200 (Japan). Abstract biotites from granites of the four intervals of hole depths (156,1–158,0; 174,6–176,5; 225,0–227,0; 239,6–242,0 m). They is characterized by high-iron content (0,96–1,00) and high-aluminous content (16–24 %). Biotites from different depths of the hole differ in their chemical composition. Biotites of small-medium-grained granites from the upper part of the hole section (156,1–158,0 m) are the most aluminous. They are pure siderofillite composition. Biotites from deeper medium-coarse grained granites (174,6–176,5; 225,0–227,0; 239,6–242,0 m) is annite-siderofilitovogocomposition. Biotites of Ruska-Polyana granites have a wide range of titanium content. Average content TiO2 in biotites from different depths of the hole varies from 1.65 to 3.08 %. The smallest of its content (1.65 %) recorded in the biotites from granites of the upper section of the hole (156,1–158,0 m). Biotites from a deeper part of the section of the hole the average TiO2 content is 2,71–3,08 %. Biotite from the upper part of the hole section (156,1–158,0 m) similar to biotite from Kamyani-Mogyly granites on the content of TiO2. And biotites from intervals depths 174,6–176,5; 225,0–227,0;, 239,6–242,0 m like biotites from Perga granites, Leznyky granites. Test biotites (239,6–242,0 m) are enriched in Zn (0,17–0,26 %). They have higher contents of Ta (0.13 %) compared to Nb (to 0.03%) and Cl (0,57–1,05 %) compared with F (0–0,23 %).