TY - JOUR

T1 - Platinum Content and Formation Conditions of the Sulfide PGE–Cu–Ni Nyud-II Deposit of the Monchegorsk Pluton, Kola Peninsula, Russia

AU - Chashchin, V.V.

AU - Petrov, S.V.

AU - Kiseleva, D.V.

AU - Savchenko, Ye. E.

N1 - Publisher Copyright: © 2021, Pleiades Publishing, Ltd.

PY - 2021/5/27

Y1 - 2021/5/27

N2 - Abstract—The article presents the results of studying the chemical composition of ore-bearing rocks, as well as the mineralogy of base metal sulfides and platinum group elements (PGE), of the Nyud-II sulfide PGE–Cu–Ni deposit in the southwestern part of the Nyud massif of the Monchegorsk Pluton (Monchepluton).The ores of the deposit are represented by vein-disseminated and nest-schlieren types. They are characterized by significant predominance of Pd over Pt, fractionation of low-melting PGE (PPGE subgroup) with respect to high-melting ones (IPGE subgroup), and close correlations of Ni and Cu with S in the presence of increased As, Se, Te, and Bi contents. The S/Se ratios in ore (3470−3530) correspond to the mantle values. Among the platinum group minerals (PGM), the most widespread are Pt and Pd bismuth–tellurides and tellurides (merenskyite, michenerite, and moncheite), subordinate amounts of Pt–Fe alloys and sperrylite, and native osmium and Ir, Rh, and Pt sulfoarsenides (irarsite, hollingworthite, and platarsite). The formation of ore sulfide concentrations resulted from separation of an immiscible sulfide liquid upon cooling of a sulfur-saturated silicate magma with a mafic composition. Subsequent fractional crystallization of the sulfide liquid contributed to the uneven distribution of Ni, Cu, and PGE. PGE–sulfide ore formation took place in a fairly wide temperature range, starting at 1100−1000°C and ending at 600−400°C. At an early stage, IPGE minerals (native osmium and erlichmanite) separated. Upon cooling to a temperature of 1000−900°C, the sulfide liquid fractionated with the formation of monosulfide solid solution (mss), in which compatible IPGE were concentrated, and a residual sulfide liquid enriched in Ni, Cu, PtPGE, and chalcophile elements. With a further decrease in temperature (to 600°C), Pt–Fe alloys, sperrylite, and IPGE + Pt sulfoarsenides crystallized, with separation of the residual sulfide melt enriched in Cu, PPGE and chalcophile elements. At 600−400°C, ore formation ended with the complete crystallization of base metal sulfides and the formation of Pt and Pdbismuth–tellurides and tellurides.

AB - Abstract—The article presents the results of studying the chemical composition of ore-bearing rocks, as well as the mineralogy of base metal sulfides and platinum group elements (PGE), of the Nyud-II sulfide PGE–Cu–Ni deposit in the southwestern part of the Nyud massif of the Monchegorsk Pluton (Monchepluton).The ores of the deposit are represented by vein-disseminated and nest-schlieren types. They are characterized by significant predominance of Pd over Pt, fractionation of low-melting PGE (PPGE subgroup) with respect to high-melting ones (IPGE subgroup), and close correlations of Ni and Cu with S in the presence of increased As, Se, Te, and Bi contents. The S/Se ratios in ore (3470−3530) correspond to the mantle values. Among the platinum group minerals (PGM), the most widespread are Pt and Pd bismuth–tellurides and tellurides (merenskyite, michenerite, and moncheite), subordinate amounts of Pt–Fe alloys and sperrylite, and native osmium and Ir, Rh, and Pt sulfoarsenides (irarsite, hollingworthite, and platarsite). The formation of ore sulfide concentrations resulted from separation of an immiscible sulfide liquid upon cooling of a sulfur-saturated silicate magma with a mafic composition. Subsequent fractional crystallization of the sulfide liquid contributed to the uneven distribution of Ni, Cu, and PGE. PGE–sulfide ore formation took place in a fairly wide temperature range, starting at 1100−1000°C and ending at 600−400°C. At an early stage, IPGE minerals (native osmium and erlichmanite) separated. Upon cooling to a temperature of 1000−900°C, the sulfide liquid fractionated with the formation of monosulfide solid solution (mss), in which compatible IPGE were concentrated, and a residual sulfide liquid enriched in Ni, Cu, PtPGE, and chalcophile elements. With a further decrease in temperature (to 600°C), Pt–Fe alloys, sperrylite, and IPGE + Pt sulfoarsenides crystallized, with separation of the residual sulfide melt enriched in Cu, PPGE and chalcophile elements. At 600−400°C, ore formation ended with the complete crystallization of base metal sulfides and the formation of Pt and Pdbismuth–tellurides and tellurides.

UR - http://www.scopus.com/inward/record.url?scp=85107000030&partnerID=8YFLogxK

U2 - 10.1134/S1075701521020021

DO - 10.1134/S1075701521020021

M3 - Article

VL - 63

SP - 87

EP - 117

JO - Geology of Ore Deposits

JF - Geology of Ore Deposits

SN - 1075-7015

IS - 2

ER -