stripes
This is the largest granite intrusion on the Kola Peninsula with an area of 1300 km2. The enclosing rocks are Archaean granite gneisses. The intrusion is divided into northern and southern parts by an east-west line of gneisses. The granites contain aegirine and arfvedsonite. The southern part of the massif is characterised by a more complicated structure, there being a large number of dykes. The dykes comprise aegirine-augite-ferrohastingsite granites, granosyenites, quartz syenites and natrolite syenites and these alkaline dykes cut earlier dykes of picrite and diabase. In the alkaline granites of the Western Keiv linear structures are apparent as manifested by orientated dark coloured minerals and there are huge xenoliths of country rocks. Erosional "windows" reveal granodiorite, oligoclase granite, plagioclase microcline granite and metagabbro. The main rock-forming minerals of the aegirine-arfvedsonite granites are quartz, microcline, albite, alkaline amphiboles, aegirine and lepidomelane with accessory titanite, zircon, orthite, apatite, fluorite, magnetite and sulphides. The main rock-forming minerals of the granosyenites and quartz syenites are plagioclase (albite, oligoclase), microcline, quartz and aegirine-augite with the accessories titanite, zircon, apatite, fluorite, magnetite, sulphides, chevkinite, astrophyllite, pyrochlore, monazite, britholite and molybdenite.
BATIEVA, I.D. 1976. The petrology of alkaline granitoids of the Kola peninsula. Nauka, Leningrad. 223 pp.
BATIEVA, I.D. et al. 1985. Magmatic formations of the north-eastern part of the Precambrian Baltic Sheild. Nauka, Leningrad. 175 pp.