Surmetashskii

Surmetashskii is a ring intrusion which is elliptical in plan. The country rocks are limestones, dolomites and schists. There are two principal intrusive phases: alkaline quartz-bearing syenites and tourmaline-bearing granites. Nepheline syenites are concentrated in the south of the intrusion with the central areas occupied by alkaline olivine-bearing melano- and leucocratic syenites. These rocks gradually pass into quartz-bearing syenites, in which veins and irregular patches of pegmatite and dykes of hybrid syenite are developed as well as skarn xenoliths.