stripes
The occurrences of Goudzhekitskii (Fig. 186) and Gorbylak, of 0.25 km2, are located at the contact Lower Proterozoic granites and granite-gneisses with crystalline schists and gneisses of the same age. The occurrences mainly comprise biotite-nepheline syenites amongst w as hich bodies of biotite-riebeckite-nepheline syenite and melteigite are frequent.The rocks of these occurrences generally have gneiss-like structures. The nepheline syenites are medium-grained grey rocks composed of microcline-perthite, nepheline, biotite, ilmenite, titanite, apatite and occasionally schorlomite. Secondary minerals are albite, cancrinite, muscovite, calcite, analcime and epidote. Microcline and nepheline are sometimes isolated as glomeroporphyritic aggregates which are surrounded by fine-grained microcline-nepheline-biotite rock. Metasomatic zones of biotite-albite rock are found.
ANDRE’E V, G.V. 1981. Petrology of the association of the potassium, nepheline and peralkaline syenites. Nauka, Novosibirsk, 85 pp.
ARKHANGELSKAYA, V.V. 1974. Rare-metal alkaline complexes of the southern margin of the Siberian platform. Nedra, Moscow, 128 pp.
ZHIDKOV, A.Ya. 1968. Apatite-bearing alkaline intrusions of the North Baikal area. In V.I. Smirnov et al. (eds) Apatite, 126-132. Nauka, Moscow.
