Alkaline Rocks and Carbonatites of the World

Setup during HiTech AlkCarb: an online database of alkaline rock and carbonatite occurrences

Western Keiv

stripes

Occurrence number: 
136-12-013
Country: 
Russia
Region: 
Kola and Karelia
Location: 
Longitude: 36.5, Latitude: 67.78
Carbonatite: 
No

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.

Economic: 
A zircon and rare-earth mineralization is present and there is a deposit of amazonite which is mined (Batieva et al., 1985).
Age: 
A Sm-Nd isochron gave an age of 2100_+50 Ma and the lead method on zircon and titanite 2400_+50 Ma (Batieva et al., 1985).
References: 

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.

Map: 
Fig. 2_13. Western Keiv (north of map), White Tundra (southern part of map) and Sakhariokskii (small intrusion of syenite and nepheline syenite right of centre) (after Batieva, 1976, Fig. 5).
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith