Ore mineralization of gold-uranium occurrences Ozernoe and Lagernoe (Kuolayarvi structure, North Karelia)

Abstract

Alkaline-carbonate metasomatites of fault zones are widely distributed within all Precambrian shields. Their studying has attracted the close attention of researchers in connection with the confinement of various concentrations of ore-forming elements. In addition, a clear structural control of metasomatites, their composition and stages of development are of great importance for the predictive assessment of geological structures. Kuolayarvi zone is one of the most promising in the Republic of Karelia in terms of prospecting, evaluating and possible industrial production of gold and uranium. On its territory, the Mayskoye gold deposit has been identified, as well as a number of complex gold-uranium ore occurrences, among which Ozernoye and Lagernoye are of the greatest interest. This paper discusses the features of the ore mineralization of these ore manifestations, as well as the dependence of its composition on the primary rock that has undergone hydrothermal-metasomatic study. In the general sequence of forming ore minerals, six parageneses (rock, uranium ore, sulphide, selenide-telluride, low-temperature and hypergenic) have been revealed. It has been also established that gold mineralization is associated with the selenide-telluride paragenesis, and uranium – with the uranium ore and low-temperature ones. The interrelation of the ore parageneses with the global stages of the development of the Kuolayarvi structure (Svekofennian and Paleozoic activization) has been shown. New data on the Re-Os isotope dating of sulfide formation minerals (chalcopyrite and molybdenite), with which gold mineralization is closely associated, have been presented. The so-called "chemical" isotope age of uraninite has been calculated as well. The obtained isotopic data allow us to consider that the formation of minerals of the uranium and gold ore formations took place during the period of the Svekofennian activation of the Kuolayarvi structure.

Keywords

• gold
• uranium
• metasomatites
• North Karelia
• Kuola-Panayarvinskaya zone
• Precambrian