A.G. PAKHALKO, S.V. KASHIN (VSEGEI)

Metasomatic assemblages of mafic rocks in the Vuruchuaivench Massif, the Monchegorsk Pluton

The petrographic composition in the upper part of the Vuruchuaivench Massif section, the Monchegorsk layered complex, was studied. Samples from the surface and core samples from drilling wells to a depth of 280,1 m were taken for studying. The prevalence of secondary metasomatic minerals was identified in this part of the section. Plagioclase is the only primary igneous mineral found in the samples. Three associations and the sequence of metasomatic mineral crystallization are distinguished. Propylitization – α-, β-zoisites, clinozoisite and chlorite; beresitization – quartz, sericite, carbonate and sulfides; amphibolization – two generations of amphibole. The formation of amphiboles is a result of metasomatic crystallization rather then the replacement of primary magmatic pyroxene. PGE minerals are represented by arsenide, sulfoarsenide, and tellurobismuthide of platinum and palladium, which are associated only with secondary silicates.
Keywords: Monchegorsk Pluton, Vuruchuaivench, propylitization, beresitization, amphibolization, zoisite, PGE mineralization.