Chemistry of minerals of felsic extrusive rocks of the east Baymak area and a problem of hybridism in their genesis
A.M. Kosarev, S.A. Svetov, S.Yu. Chazhengina, G.T. Shafgullina
UDК 551.21+552.11
The Baymak ore district hosts numerous small Au-rich massive sulfde polymetallic deposits, which is a distinctive feature in comparison with other regions of the West-Magnitogorsk zone (Seravkin, 1986). According to geophysical data, the Baymak block is characterized by low level of gravity feld intensity because of signifcant volume of felsic rocks and reduced thickness of the granulite-basite layer (Seravkin, Tsvetkova, 1982). The volcanic and volcanosedimentary rocks, which host massive sulfde deposits of the district, belong to the upper subformation of the Baymak-Buribay Formation (D1ems22) in the upper part of the frontal island arc (Kosarev et al., 2005). The objects of study are felsic rocks of extrusive and subvolcanic facies of the East Baymak district with phenocrysts of quartz, hornblende, pyroxene, and plagioclase. These rocks are characterized by unusual presence of relic unaltered clinopyroxene. The study of chemical composition of minerals allowed us to show that the formation of extrusive and subvolcanic felsic rocks was afected by hybridism processes responsible for the high Mg contents. These rocks belong to Mg calc-alkaline petrochemical series.
Figures 3. Tables 5. References 29.
Key words: Southern Urals, Baymak district, massive sulfde deposits, extrusive and subvolcanic felsic rocks, hybridism, pyroxene, chlorite, Zvezdnoe ore occurrence.
A.M. Kosarev, Institute of Geology UFRC RAS, 450077, Russia, Ufa, Karl Marks str, 16/2; amkosarev@mail.ru;
S.A. Svetov, Institute of Geology, KarRC RAS, Petrozavodsk; geoweb@krc.karelia.ru;
S.Yu. Chazhengina, Institute of Geology, KarRC RAS, Petrozavodsk;
G.T. Shafgullina, Institute of Geology UFRC RAS, 450077, Russia, Ufa, Karl Marks str, 16/2
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МINERALOGY № 2 2018