Mineral composition of Paleoproterozoic metamorphosed massive sulfide ore in the Kola Region (a case study of the Bragino Occurrence, South Pechenga)

Many occurrences and deposits of massive sulfide ores in the Kola Region are connected with the Paleoproterozoic Pechenga—Imandra—Varzuga Rift Belt (2.5—1.7 Ga). They are placed in volcanogenic-sedimentary complexes of South Pechenga (Bragino occurrence) and western part of Imandra-Varzugskaya structural zones (Pyrrhotite Ravine deposit, Tahtarvumchorr occurrence, etc.). The age of massive sulfide ore formation is expected to be about 1.9 Ga. The ores and their host complexes were metamorphosed under conditions close to the amphibolite facies. High degree of metamorphism of massive sulfide ores of the Kola region determined the features of their mineral composition, which are considered on the example of the Bragino occurrence. The article displays ore types, their mineral assemblages, and data on main minerals of ores: pyrrhotite, pyrite, sphalerite, marcasite, etc.