Ozernaya Varaka

Ozernaya Varaka lies to the east of the Afrikanda complex and is situated on an east-west-trending ridge of uplands. The massif intrudes and fenitizes gneisses of the Belomorskaya Archaean series. The total area of the complex is only 0.8 km2 and it has a concentrically zoned structure. The outer zone, 250 to 300 m wide, is composed of ijolite with bands of melteigite. Towards the centre this is replaced by an area of melteigites, which are patchily enriched in melanite. The central part of the massif is composed of nepheline pyroxenites. Dyke rocks are, in order of decreasing age. ijolite and urtite, biotite glimmerites, which contain pyroxene, amphibole and apatite, ijolite pegmatites, nepheline and cancrinite syenites and carbonatites; there are also younger dykes of ijolite porphyry, tinguaite and monchiquite. Carbonatites and silicate-carbonate rocks are encountered both in the inner parts of the massif and in the contact aureole. They occur as veins and lens-shaped bodies, which are considered to be metasomatic in origin, and are developed among the ijolites, melteigites, nepheline pyroxenites and fenites; occasionally they replace glimmerites. Less often, the carbonatites have sharp and cross-cutting contacts. The thickness of the carbonatite veins varies from several centimetres to 2.5 or even 3 m. The following types of carbonate-bearing rocks have been distinguished: aegirine-calcite carbonatites (ringites) with accessory zircon, pyrochlore, aegirine, nepheline and biotite; calcite, calcite-albite, cancrinite-calcite-albite and aegirine-calcite-albite rocks.