Geodynamic settings of Silurian - Early Devonian volcanism in the north of the Sakmara zone (the Southern Urals)

Abstract

The work provides characteristics of the Karamolinsky and Blyavinsky volcanic complexes, which were identified by I.A. Smirnova, V.L. Cherkasov, V.T. Tishchenko, I.B. Seravkin in the Mednogorsk region in the rank of strata. Based on findings of graptolites in limestones and siliceous shales, intercalations among pillow basalts and massive basaltic flows, the sequence is dated as the Middle to Upper Llandoverian. Based on the presence of facies replacement of the Karamolinsky sequence with siliceous rocks of the Sakmara Formation, the age of the Karamolinsky sequence is assumed to be S–D1. The Karamolinsky sequence (according to A.D. Petrovsky, L.D. Chegodaev) is identified with the Blyavinsky formation. We propose that the basalts of the southern wall of the Blyavinsky quarry and their analogues containing interlayers of siliceous rocks with graptolites (S1) be included in the Karamolinsky sequence and Blyavinsky formation, and the ore-hosting section of the Blyavinsky and Komsomolsk deposits with low-titanium basalts and acidic polyfacial rocks, is classified as the Blyavinsky formation (S–D1). The geodynamic conditions for the formation of the Karamolinsky strata are discussed. Materials on the composition and age of the Karamalinsky formation of the Maksyutov complex and pyrite mineralization of the Yuluk group of deposits in the Uraltau zone are considered. It is concluded that it is possible to partially compare the strata of the Maksyutov complex and the Silurian-Early Devonian volcanic sulfide-bearing strata of the Mednogorsk ore region.