MINERALOGICAL AND GEOCHEMICAL EVIDENCE FOR GRANITE METASOMATISM IN DIKES IN THE NORTH OF THE BEREZOVSKOE ORE FIELD (Middle Urals)
S.Yu. Stepanov1, E.S. Shagalov1, R.S. Palamarchuk2, A.V. Kutyrev3, L.N. Sharpenok4, F.M. Nabiullin5, A.N. Troshkina5
1Zavaritsky Institute of Geology and Geochemistry, Ural Branch of the Russian Academy of Sciences, ul. Akademika Vonsovskogo 14, Yekaterinburg, 620016, Russia
2South Urals Federal Research Center of Mineralogy and Geoecology, Ural Branch of the Russian Academy of Sciences, territory of the Ilmeny State Reserve, Miass, Chelyabinsk Region, 456317, Russia
3Institute of Volcanology and Seismology, Far Eastern Branch of the Russian Academy of Sciences, bul’v. Piipa 9, Petropavlovsk-Kamchatsky, 683006, Russia
4A.P. Karpinsky Russian Geological Research Institute, Srednii prosp. 74, St. Petersburg, 199106, Russia
5OOO Berezovskii Rudnik, ul. Berezovskii trakt 1, Berezovskii, Sverdlovsk Region, 623703, Russia
Keywords: Gold deposits, geochemical gold mineral assemblage, REE, apogranite metasomatites, Middle Urals, Berezovskoe ore field
Abstract
We present results of petrographic, geochemical, and mineralogical studies of apogranite metasomatites associated with sulfide-quartz gold ore veins. The studies show a predominance of muscovite and quartz-muscovite metasomatites. Formation of muscovite metasomatites was accompanied by the accumulation of W, Sc, Zr, Hf, Ga, REE, U, Th, Ta, and Nb and the genesis of new accessory minerals: monazite-(Ce), apatite, zircon, scheelite, W-containing rutile, uraninite, thorianite, cassiterite, etc. Compared with the primary granites, quartz-muscovite metasomatites are richer in Pb, Bi, As, Sb, Co, Ni, Ba, In, Cd, Mo, Te, Ag, and Au (elements of the gold ore assemblage). The high contents of these trace elements are due to abundant galena, fahlores, chalcopyrite, and pyrite among the accessory minerals. Metasomatism of granites was followed by the removal of SiO2, which was then spent for the formation of quartz veins. We have revealed that the distribution of metasomatites of different types within a dike body affects directly the distribution of sulfide-quartz veins and thus determines the ore content of the dike body fragments.
DOI: 10.15372/RGG2019176
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