Types of massive sulphide deposits in the Urals

Abstract

Massive sulphide deposits in the Urals are found within volcanic and volcanic-sedimentary sequences of Ordovician to Middle Devonian ages. Four types of economic sulphide deposits have been recognized: Cyprus, Besshi, Urals and Baimak. The Cyprus-type copper sulphide deposits are hosted by mafic volcanites that occur in the basal parts of Palaeozoic volcanic sequences. The Besshi-type copper-zinc deposits are located within clastic sedimentary rocks intercalated with basalts and andesites. Zinc-copper deposits of the Urals-type are hosted by bimodal rhyolite-basalt assemblages, which occur at a higher stratigraphic level than those of Cyprus- and Besshi-types. The Baimak-type zinc-copper-barite deposits are associated with intrusive quartz porphyries which occur in the upper parts of bimodal volcanic successions. In addition there are some sulphide deposits of zinc-lead-barite and zinc-copper composition hosted by Ordovician terrigenous sequences which occur within depressions in Precambrian blocks. These types of sulphide deposits have been formed at various stages of divergence and convergence of the Earth's crust during the orogenic history of the Urals.