Литосфера (Jun 2017)
Cupriferous basalts of the Northern Urals
Abstract
Characteristics and distinctive features of cupriferous basalts in the world are given. Deposits of the Superior Lake in the United States are considered as a reference. In the Northern Urals, drilling explored the Khultym’insk mineralized zone, associated with almond-stone olivine basalts and their tuffs of different granulometry. A detailed study of a new for the Urals type of copper mineralization into basalts for their conformity with known cupriferous volcanites. The main ore mineral is native copper, up to 10 mm size. Analysis of the distribution of native copper and sulphide mineralization in space according to drilling data made it possible to reveal mineral zonality in the area: the central part contains the releases of native copper, sulfide mineralization is developed on the periphery (both above and below in the section and in the flank parts), closer to the centre with a poor dissemination of chalcopyrite, and at a distance - pyrite. As a whole, the Khultym’inskaya mineralized zone has a gentle dip, thickness of up to 166-228 m and extent of up to 3500 m, including the intervals with the development of native copper, was discovered by drilling. This mineralized zone has been traced by inclination of more than 500 m. Despite its wide distribution, the mineralization is very dispersed and according to the results of testing the copper content is extremely low (less than 0.1%), and only a small number of samples contain more than 0.5% copper. Relatively elevated concentrations of copper (from 0.1 to >1%) are localized in spatially disconnected, small-sized bodies. The mineralized zone is controlled by thrust, it is probable that the ore-bearing fluids have been inflated over this structures. A copper ore manifestation of a new type, unconventional for the Urals with a stratified deposit of disseminated native copper in the basic section of the Upper Tournaisian age, has been revealed. The large areas occupied by rift basalts on the eastern slope of the Northern Urals make it possible to assume the prospect of this type mineralisation. Rift structures of Eastern Siberia are potential as well.
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