Vostochno-Verkhotursky gabbro-diorite-granodiorite massif (Middle Urals): new data on composition, formation conditions, age and metallogeny
Relevance of the problem. In the Urals, in connection with the solution of the problem of supplying the operating non-ferrous metallurgy enterprises with local raw materials, a number of copper-porphyry ore-bearing deposits have been involved in the industrial development in the last decade; low-sulfidation mineralization is localized mainly in dioritic intrusive massifs. The presence of large-scale mineralization of native copper in the diorites of the Vostochno-Verkhotursky massif testifies to the need for its comprehensive study and determination of ore-forming appurtenances. Purpose of the paper is to determine the formation and age appurtenances, as well as the metallogenic specialization of the eastern part of Verk- hotursko-Isetskaya zone (Middle Urals) of the Vostochno-Verkhotursky massif within which mineralization of native copper was previously identified. Results. Petrographic, geochemical, and isotope-geochronological studies of the gabbro, diorite and granodiorite massifs were carried out (SiO2 -53.97-67.32%, K2O - 1.04-2.65%) and gabbro-diorite dikes occurring among them SiO2 - 54.50-56.50%, K2O - 0.96-1.50%). The predominantly corniferous rocks of the massif belong to a single homodromous calci-alkalic normal-alkalic series of a moderately potassic type. Dyorites of dikes are comagmatic to enclosing rocks. The massif is formed in the abyssal-mesoabyssal conditions of the supra-subduction situation at the continental margin of the zone development. The U-Pb age of the investigated rocks of the massif is determined by zircon (the method of laser ablation) in 339.2 2.8 million years (Carbonic period). The formation of the massif occurred within the tectonic block with the basement of the Proterozoic age of the sialic composition. The presence of high concentrations of F in accessory apatites (up to 3.5-4.2%) at relatively low Cl (up to 0.5%) and SO3 (up to 0.4-0.9%) indicates a possible gold-rare metal specialization of formations. Conclusion. To determine conditions for the formation of the mineralization of native copper among the supra-subduction dioritoids of the Middle Carbonic period, its age, ore-bearing belonging, and scale, it is necessary to further study both the formations of the Vostochno-Verkhotursky massif (including those that underwent secondary alterations) and other dioritoid massifs in the eastern part of the Verkhoturskaya-Isetskaya zone.