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Vol. 21 (2018 year), No. 1, DOI: 10.21443/1560-9278-2018-21-1

Kalinin A. A., Chernyavsky A. V.
Alteration of rocks, massive sulfide ores and perspectives for gold mineralization of the Panarechenskaya structure (the Kola Peninsula)

The present paper has been written on the base of petrographical, geochemical, and mineralogical study of massive sulfide ores and their host rocks from the Panarechenskaya tectonic-volcanic structure in the central part of the Imandra-Varzuga belt. The massive sulfide deposit is situated in the northern part of the western caldera of the Panarechenskaya structure in medium-acid volcanics of the Samingskaya unit. Massive sulfide ore forms lens bodies 0.1–4 m thick, and have been traced with drillholes for 100 m. Lenses of massive sulfides are accompanied by zones of intense sulfide dissemination up the cross section. Host rocks are intensively altered, the main alteration processes are carbonatization and silicification. Silicification is accompanied by re-deposition of ore minerals in quartz and quartz-carbonate veinlets. The main ore mineral is pyrite, minor sulfides are chalcopyrite, pirrhotite, marcasite, arsenopyrite, galena, sphalerite, and some other sulfides, as well as rarely tellurides of Pb, Ag, Bi, Au, and native gold (electrum). Precious metal mineralization is noted mainly in zones of disseminated sulfides near massive sulfide lenses. Au content in the ores is 0.25–0.35 ppm, Ag content is 1.75–2.25 ppm, Au/Ag ratio varies within 1/6–1/7 interval. High geochemical background can serve as a source of precious metals for formation of gold deposits during later superimposed hydrothermal processes. Our investigations have shown that the Panarechenskaya structure, and, first of all, its western caldera, is the area promising for gold deposits, and exploration works should concentrate on searching for quartz-carbonate mineralized veins and zones of silicification.

(in English, стр.10, fig. 2, tables. 1, ref 19, adobe PDF, adobe PDF 0 Kb)

Vol. 24 (2021 year), No. 1, DOI: 10.21443/1560-9278-2021-24-1

Neradovsky Y. N. , Miroshnikova Y. А., Kompanchenko A. А., Chernyavsky A. V.
On unique stone beaches on the Arctic coast of the Kola Peninsula

The results of studies of 11 stone beaches on the coast of the Barents Sea in the area of the Teriberskaya Bay have been presented. The studies were carried out from 2017 to 2019. As a result of the work, the structure of the beaches, their size, the composition of clastic material and the relationship with bedrocks were studied in detail. The genetic link between beaches and sea terraces has been established. Special attention has been paid to the morphology of beach clastic material, the conditions of its formation, and its role in abrasion activity. It has been shown that the clastic material of the beaches mainly corresponds to boulders equal to 100–1,000 mm, to a lesser extent to pebbles 10–100 mm, and rarely – gravel 1–10 mm. Individual boulders reach 2,000 mm. Sandy fractions in the composition of beach sediments are practically absent. The roundness of the fragments is high, semi-circular and rounded grains predominate, the most perfect shape of the rounded fragments is a biaxial ellipsoid or egg. Perfectly rounded boulders and pebbles in some areas account for up to 30 % of beach deposits. Measurements of the parameters of the egg-shaped pebbles have shown that they are close to the parameters of the "golden section" of the egg, i. e. meet the most durable form, resistant to destruction. Thus, the process of abrasion of the beach debris is directed towards their acquisition of the most energetically stable state. This suggests that the original shape of the debris contained a solid core in the form of a biaxial ellipsoid.

(in Russian, стр.10, fig. 12, tables. 0, ref 26, AdobePDF, AdobePDF 0 Kb)

Vol. 25 (2022 year), No. 1, DOI: 10.21443/1560-9278-2022-25-1

Neradovsky Yu. N., Miroshnikova Ya. A., Companchenko A. A., Chernyavsky A. V.
About terraces on the shore of the Teriberskaya Bay of the Barents Sea (the Kola Peninsula)

The paper considers the results of the study of modern terraces on the coast of the Lodeyny Peninsula in the Barents Sea. According to field observations, decoding of space and geodetic maps and volumetric modeling, signs of three terraces have been identified. Two terraces having a rear seam, a cliff, a brow and horizontal platforms have been studied in more detail. The rear seams are located at 7 and 30 m, and the edges at 10 and 40 m above the sea level. The third terrace is confined to the level of 40–60 m, and has not been studied in detail. According to estimates, the first two terraces were formed about 3,300 and 6,000 years ago respectively. The 1st terrace characterizes the period of slow land rise by 10 m, at the speed up to 3 mm/year, which began about 3,300 years ago and continues to the present. It is characterized by a uniform sea retreat of about 15 mm/year. The erosion products of this terrace are common in the lateral zone and represent modern marine sediments, including beaches forming a new terrace. The 2nd terrace characterizes to the dynamics of rapid land rise by 30 m at a speed of about 11 mm/year, which occurred in the period from 6,000 to 3,300 years ago. The erosion products of this terrace are most common on the coast and are found at a distance of 100 m to 2–3 km from the shore. It is assumed that the speed of movement of the coastline during the retreat of the sea was different and reached up to 900 mm/year. According to the authors, preliminary data indicate the instability of the territory and the manifestation of block movements, which may have a negative impact on the development of infrastructure.

(in Russian, стр.12, fig. 14, tables. 0, ref 17, AdobePDF, AdobePDF 0 Kb)