THE PGE ORE MINERALIZATION IN THE MONCHEGORSK MAGMATIC LAYERED COMPLEX (KOLA PENINSULA, RUSSIA)

Abstract

The paper contains new data on low-sulfide PGE occurrences related to the Early Proterozoic(~2450–2503 Ma) plutons within the Monchegorsk ore district (the northeastern part of the Baltic Shield). The most important PGE occurrences relate to the conjugation zone of the Monchetundrovsk massif and Monchegorsk pluton and to some intrusives at the southern frame of the Monchegorsk pluton. It was found that platinum and palladium bismuthotellurides are predominant in the vein and veinlet–disseminated Cu–Ni ores of the Monchegorsk pluton, while niggliite, sopcheite, and sperrylite are more rare. Sperrylite, hollingworthite, irarsite, and palladoarsenite occur in the marginal rock series, except for compounds of the system Pt–Pd–(Ag)–Te–Bi. The minerals of the braggite–cooperite-vysotskite row, bismuthotellurides of Pt and Pd, and sperrylite are common in the ore-bearing horizons of the rhythmically layered zone within the Monchetundrovsk massif. The most variable assemblage of PGE minerals was found in ore occurrences at the conjugation zone of the massifs and in intrusives of the southern frame of the Monchegorsk pluton. This assemblage includes alloys, sulfides, bismuthotellurides, and arsenides of Pt and Pd, as well as minerals of the systems Pd–As–Sb, Pd–As–Te–(Sn), Pd–Ni–As, Pd–Ag–Te, Pd–Pb–(S, Se), Pd–As-O and sulfarsenides of PGE, Ni, and Co. The PGE minerals associate with minerals of Au and Ag. Most of these minerals were found for the first time in the Monchegorsk district. The evolution of PGE assemblages in the process of the massifs crystallization is shown for the studied ore occurrences.