Metamorphism, metasomatism and ore mineralization of rocks of the kharbei metamorphic complex (Polar Urals)

Abstract

The results of petrographic, petrochemical and microprobe studies in varying degrees of modified amphibolites of the Kharbei metamorphic complex are presented. It was established that the rocks underwent two stages of metamorphism: high levels of amphibolite facies of moderate pressures and epi-dote-amphibolite facies of elevated pressures. The secondary processes of clinocitization, albitization, muscovitization and silicification characterize calcium, sodium, potassium and silica metasomatism. The formation of sulfides is closely related to the silicification of rocks. Two stages of low-temperature transformations were diagnosed for chlorite (245–355 °С for ripidolite, 135–255 °С for picnochlore). The sulphides are pyrite, chalcopyrite, galenite, sphalerite and clinopyrrhotine. For the first time in the form of inclusions in pyrite in the study area found - spionkopite, covellite, covellite-klockmannite and minerals of silver and gold. Native gold, electrum, petrovskaite and yutenbogaardtite were formed from hypogenic low-temperature solutions. Acanthite, hessite, acanthite-hessite, naumannite-acanthite, hessite-acanthite-naumannite, native silver, silver iodite and silver chloride were formed during superimposed hypergene processes.