Open AccessFahlbands of the Keret archipelago, White Sea: the composition of rocks and minerals, ore mineralization
Author(s) -
Laysan I. Salimgaraeva,
С. Г. Скублов,
А. В. Березин,
О. Л. Галанкина
Publication year - 2020
Publication title -
zapiski gornogo instituta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.707
H-Index - 13
eISSN - 2541-9404
pISSN - 2411-3336
DOI - 10.31897/pmi.2020.5.2
Subject(s) - pyrrhotite , pyrite , geology , chalcopyrite , geochemistry , mineralization (soil science) , pentlandite , metamorphic rock , mineralogy , outcrop , volcanogenic massive sulfide ore deposit , sulfide minerals , sulfide , sphalerite , metallurgy , copper , materials science , soil science , soil water
This paper presents a complex mineralogical and geochemical characteristic (based on SEM-EDS, ICP-MS analysis) of the fahlband rocks of the Kiv-Guba-Kartesh occurrence within the White Sea mobile belt (WSMB). The term “fahlband” first appeared in the silver mines of Kongsberg in the 17th century. Now fahlbands are interlayers or lenses with sulfide impregnation, located in the host, usually metamorphic rock. The level of sulfide content in the rock exceed the typical accessory values, but at the same time be insufficient for massive ores. Fahlbands are weathered in a different way than the host rocks, so they are easily distinguished in outcrops due to their rusty-brown color. The studied rocks are amphibolites, differing from each other in garnet content and silicification degree. Ore mineralization is represented mainly by pyrrhotite and pyrite, and pyrrhotite grains are often replaced along the periphery by iron oxides and hydroxides, followed by pyrite overgrowth. At the same time, the rock contains practically unaltered pyrrhotite grains of irregular shape with fine exsolution structures composed of pentlandite, and individual pyrite grains with an increased Ni content (up to 5.4 wt.%). A relatively common mineral is chalcopyrite, which forms small grains, often trapped by pyrrhotite. We have also found single submicron sobolevskite and hedleyite grains. The REE composition of the fahlband rocks suggests that they are related to Archean metabasalts of the Seryakskaya and Loukhsko-Pisemskaya structures of the WSMB, rather than with metagabbroids and metaultrabasites common in the study area.