Self-Organization of the Khibiny Alkaline Massif (Kola Peninsula, Russia)

Abstract

The world's largest Khibiny alkaline massif occupies the area of about 1327 km2 in the extreme West of the Kola Peninsula, at the contact of rocks of the Imandra-Varzuga Proterozoic greenstone belt and the Archaean metamorphic complexes of the Kola-Norwegian megablock (Fig. 1). According to Pb-Pb, Rb-Sr and Sm-Nd dating (Arzamastsev et al., 2007), the age of the main rock types of the Khibiny massif is 380–360 million years. About 70% of the massif area is occupied by nepheline syenites (foyaite) monotonous in composition which are, in most works, subdivided into two equal parts: foyaite proper (in the center) and "khibinite" (surrounding them), separated from each other by a zone rock complex of the Main Ring. Besides, practically every geological map of the Khibiny massif highlights the concentric zones of massive and trachytic khibinite and foyaite, along the edge and in the center, and on both sides of the Main Ring, respectively.