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Analysis of the genetic relationship of Sn-bearing granitoids with ultrapotassic basic magmatism showed that their metallogeny was determined by the geochemistry of a specific reservoir localized in the continental lithosphere mantle (metasomatized mantle). The granitoid formation is well explained by the binary model of mixing of primary melts (products of the metasomatized mantle) with the continental crustal material. Geochemical studies of basic magmatism of different ages showed that the specific lithosphere reservoir formed in the Middle-Late Jurassic and existed at least till the late Late Cretaceous, i.e., during both tin metallogenic epochs of the Chukchi region.

The article is devoted to the features of the system grounding and device of electrical networks (EN) and electrical installations (EI) in the continental zone of the Arctic. The traditional grounding devices providing grounding of EN and EI in the Arctic regions are ineffective or their device is impossible. These conclusions are defined by parameters of climate and properties of soil in the considered zone. The most important parameters of climate are a wide year temperature difference and big depths of soil frost penetration caused by it. Soil has very high electrical resistance and has the big hardness and density. During the cold period which has big duration (up to nine and more months) there is a soil frost penetration on tens of meters, forming areas of so-called permafrost. The conditions listed above make very difficult or impossible the use of traditional ways of the protective grounding device according to regulatory requirements. Methods of researches for the Arctic zone soil such as a method of a trial electrode and vertical electric sounding are described. Their advantages, shortcomings and application conditions are given. Special ways of the device of protective grounding such as natural grounding conductors, chemical, deep laying, portable, with application of a way of warming of a surface and zone around grounding conductors, ways of special processing of soil are offered. Conditions of their application and feature of the device are given. Each of the offered ways has restrictions of field of use. So, for example, natural grounding conductors are possible in the presence of reinforced concrete foundations. Justifications for using certain materials for grounding conductors are given in the work. Coverings are suitable for soil conditions of the Arctic copper or zinc. The usage of copperplated steel grounding conductors is possible.

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