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Vol. 19 (2016 year), No. 1, DOI: 10.21443/1560-9278-2016-1/1
Kudryashov N. M., Skublov S. G., Kalinin A. A., Lyalina L. M.
Mineralogical and geochemical characteristics of zircon from
diorite porphyry dyke in Sergozerskoe gold occurrence (the Strel'ninsky greenstone belt, Kola region)
Mineralogical and geochemical investigation of zircon from diorite porphyry from Sergozerskoe occurrence has been carried out. Study of morphology and inner structure of zircon crystals in back scattered electron rays as well as assaying for content and distribution of Rare Earth Elements in mineral grains have given important information about conditions of crystallization and following metasomatic alteration of zircon. Zircon characteristics show that it crystallized in a melt, enriched in fluid phase. Fluid influence lasted after zircon crystallization, this reflected in uneven composition of the mineral and in configuration of REE spectra, typical for metasomatic zircon. Similar zircon characteristics have been noted in zircons from other gold occurrences in greenstone belts in the Kola region
(in Russian, стр.0, fig. 0, tables. 0, ref 0, Adobe PDF, Adobe PDF 0 Kb)
Vol. 20 (2017 year), No. 1, DOI: 10.21443/1560-9278-2017-20-1/1
Kalinin A. A., Savchenko Ye. E.
Bismuth-silver mineralization in the Sergozerskoe gold occurrence
Bismuth-silver mineralization attendant to gold mineralization in the Sergozerskoe gold occurrence has been studied in detail. Bi-Ag mineralization is connected with diorite porphyry dykes, which cut volcanic-sedimentary Lopian complexes of the Strel'ninsky greenstone belt – hornblendite and actinolite-chlorite amphibolites, biotite and bi-micaceous gneisses. Distribution of Bi-Ag mineralization similar to gold mineralization is controlled by 80 m thick zone of silicification. Bi minerals are found in brecciated diorite porphyry. Bismuth-silver mineralization includes native metals (bismuth, electrum, silver), tellurides (hedleyite, hessite), selenides (ikunolite), sulfides and sulfosalts of Bi and Ag (matildite, lillianite, eckerite, jalpaite, prustite, acanthite, a few undiagnosed minerals). All Bi and Ag minerals associate with galena. Composition of mineralization evolved from early to late stages of development, depending on intensity of rock alteration. The earliest Bi-Ag minerals were native bismuth and hedleyite formed dissemination in galena, and electrum with 30-45 mass.% Au. Later native bismuth was partly substituted by silver and bismuth sulfosalts and bismuth sulfides. The latest minerals were low-temperature silver sulfides eckerite, jalpaite, and acanthite, which were noted only in the most intensively altered rocks. As soon as the process of formation of Bi-Ag mineralization is the same as formation of gold, findings of bismuth-silver mineralization can serve as a positive exploration sign for gold in the region.
(in Russian, стр.12, fig. 3, tables. 3, ref 15, Adobe PDF, Adobe PDF 0 Kb)
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. 23 (2020 year), No. 1, DOI: 10.21443/1560-9278-2020-23-1
Kalinin A. A., Savchenko Y. E.
Structures of sulfide melt crystallization as an indication of metamorphism of the ores in the Oleninskoe gold deposit
Multiphase fine aggregates of galena, pyrrhotite, freibergite, pyrargyrite, diaphorite, fizelyite, uchucchacuaite, ullmanite, and some other minerals are found in the ores of the Oleninskoe gold deposit in the Kolmozero-Voronya greenstone belt (Kola Peninsula, Russia). The aggregates are considered to be the product of crystallization of sulfide melt formed of the minerals of low-melting-point chalcophile elements (Zn, Ag, Cd, Tl, Pb, As, Sb, Bi, Se, Te, etc.) during heating to the temperature above 500 °C. This origin of the aggregates is affirmed by: 1) multiphase composition (up to 6 minerals) of the aggregates; 2) absence of signs of replacing early minerals by the late ones; 3) essential presence in the aggregates of the minerals of chalcophile elements Ag, Pb, Sb, i. e. elements with a low melting point of their compounds; 4) roundish droplet form of inclusions of minor minerals in the main sulfide, and 5) aggregates' position at the boundary sulfide – quartz or in fractures in vein minerals. Partial melting and crystallization of sulfide melts took place during Paleoproterozoic metamorphic event, when the Neoarchean sulfide-bearing rocks were mid-amphibolite metamorphosed under the temperature > 500 °C. Signs of the Paleoproterozoic metamorphism are found in the ores of the neighboring Cu-Mo porphyry Pellapahk deposit as well.
(in Russian, стр.8, fig. 6, tables. 0, ref 16, AdobePDF, AdobePDF 0 Kb)
Vol. 24 (2021 year), No. 1, DOI: 10.21443/1560-9278-2021-24-1
Kalinin A. A., Kaulina T. V., Serov P. A.
Comparison of isotope data obtained with Sm-Nd and Re-Os methods for minerals and rocks from the Ozernoe ore occurrence, Salla-Kuolajarvi belt
Sm-Nd isochrone, drawn for rock-forming and sulfide minerals from the Ozernoe ore occurrence, indicates albitite age of 1,759 ± 11 Ma. It shows synchronous formation of albitite and sulfide mineralization, and fully corresponds to the earlier defined age of rutile in albitite (1,757 ± 7 Ma U-Pb, n = 3, MSWD = 0.2), and Rb-Sr isochrone age 1,754 ± 39 Ma for biotite, apatite, albite, and WR. Recently published Re-Os ages of molybdenite 1,872 ± 23 Ma and chalcopyrite 1,891 ± 230 Ma indicate more ancient age of sulfide mineralization. These figures are in conflict with the age of rock-forming minerals, defined with Sm-Nd and Rb-Sr methods. The possibility of use of molybdenite from the Salla-Kuolajarvi belt for rock dating has been considered, and low reliability of Re-Os method for it has been shown. The reasons are the following: 1) extremely uneven distribution of Re in molybdenite, where Re content varies 1 wt.% even within one and the same grain, and 2) openness of the Re-Os system after molybdenite crystallization, Re is mobylized and partly removed from the mineral in the zone of hypergenesis. Removal of Re from molybdenite promotes erroneous ancient age of the molybdenite. According to the equations of radioactive decay, the age would be 110–130 Ma bigger if 5–6 % of Re is taken away. The conclusion is that molybdenite must be studied in detail, proved to be homogenous and unaltered, before it is used for Re-Os dating. In the other case the results will be not reliable.
(in Russian, стр.8, fig. 2, tables. 1, ref 32, AdobePDF, AdobePDF 0 Kb)
Vol. 26 (2023 year), No. 1, DOI: 10.21443/1560-9278-2023-26-1
Kalinin A. A., Kudryashov N. M., Savchenko Ye. E.
Mal'javr – the first gold prospect in the Archean conglomerates, the Kola region
A new type of prospects of gold mineralization in the Kola region is considered in the paper. The Mal'javr prospect is located in the south-western flank of the Uragubsky greenstone belt in biotite gneiss – the metamorphosed sedimentary rocks with interlayering of polymictic conglomerate, gravelite, and sandstone. Gold-bearing sulfide mineralization was found in altered rocks, which form a series of lens-shaped bodies, concentrated along a shear zone of NNE strike. The bodies of altered rocks are zonal: the central zone makes 50–80 % of the lens volume, it consists of garnet and quartz, the intermediate zone is of garnet-biotite mineral composition, and in the outer zone, which is often reduced, the main minerals are hedenbergite, hornblende, and grunerite. The metasomatic alteration is connected with an increase of iron content, decrease of Al, Si, and alkaline metals Na and K, redistribution of calcium to the outer zone of metasomatic lenses; and magnesium is inert. If compared to the unaltered gneiss, the altered rocks are depleted in Rb, Cs, Sr, Ba, Zr, Nb; and content of Cu, Zn, Mn, As, Ag, Te, W, Bi (all these elements are known to associate with gold) increases. All zones of altered rocks are rich in sulfide mineralization. Pyrrhotite and arsenopyrite are the main sulfide minerals, minor minerals are chalcopyrite, pentlandite, magnetite, tochilinite, native gold, and late pyrite and marcasite. Rock alteration and formation of sulfide mineralization happened at a high temperature > 600 °С, and the late alteration processes at ~400 °C. The arsenopyrite-gold mineralization probably formed with As and Au mobilized from the host biotite gneiss during regional metamorphism or due to pegmatite vein intrusion.
(in Russian, стр.12, fig. 8, tables. 5, ref 15, AdobePDF, AdobePDF 0 Kb)