Bykhyt-West

The intrusion is situated 8 km southwest of Dalbykha (Egorov, 1969; Butakova and Egorov, 1962) and is a concentrically zoned stock having an elongate, oval form. The earlier rocks grade into later ones towards the centre of the intrusion. Olivinite was the first phase to be intruded and forms an outer ring-dyke. Melilitolite was emplaced later and these earlier rocks are disrupted and fragmented by younger intrusions of melteigite, jacupirangite and melanephelinite. All these rocks are cut by ijolite in the western part of the intrusion. The formation of the complex was completed by intrusion of peralkaline syenite, which forms a central stock. Numerous veins of peralkaline and nepheline syenites cut all rocks.