stripes
The peralkaline and nepheline syenites of this occurrence have a migmatitic structure and extend over an area of about 20 km2. They are cut by lamprophyric dykes and veins of varying composition including carbonatites. The nepheline syenites are composed of alkali feldspar (Or59Ab41 - Or46Ab54; 35-60%), nepheline (up to 28%), plagioclase with variable composition from An1-9 to An20-36 (up to 23%), biotite (up to 2.5%), hastingsite (2-17%), and sometimes clinopyroxene (augite, aegirine). Secondary carbonates, fluorite and other accessory minerals are widespread. Lamprophyres are of variable composition, some of them containing nepheline. They include picrite porphyry, alkaline monticellite basalt, alnöite and fourchite, all of them very much altered. Minor bodies of fourchite 6 m thick, consist of clinopyroxene phenocrysts in agroundmass of aegirine-bearing clinopyroxene, zeolites and apatite. Among the youngest veins are nepheline-feldspar rocks with biotite or alkaline amphibole. One alkali picrite porphyry dyke, 0.2-1 m wide and cutting syenitic migmatite, with SiO2 36-38%, Na2O about 1% and K2O 5% has been found along the sea coast. Veins of carbonatite 10-15 cm wide cut this dyke. Picrite porphyries are altered to glimmerites with relicts of olivine, augite and diopside and pseudomorphs after melilite, amongst others.
CHERNY, V.G., VASSERMANN, B.Y., CHERNAY, I.P., SHAFRAN, E.B. and LESHCHENKO, S.E. 1977. Magmatism and formation of the folded margin of the north-east part of the Russian platform. In A.K. Krems (ed) Geology and oil-gas indications of the north-east European part of the USSR, 4: 39-45.
IVENSEN, U.P. 1964. Magmatism of Timan and the Kanin Peninsula. Nauka, Moscow and Leningrad. 126 pp.
SHCHUKIN, V.S and SMIRNOV, M.Yu. 1987. Alkali-ultrabasic rocks in the northern Timan. Doklady Akademii Nauk SSSR,294: 195-8.
SMIRNOV, M.U., DOMNIA, M.I., DONSKIH, A.V. and SHINKAREV, N.F. 1980. On the genetic relationship of the metabasites and granitoids with alkaline rocks of the North Timan (according to geological and experimental data). Zapiski Vserossiiskogo Mineralogicheskogo Obshchestva. Moskva, 109: 412-23.
TISOVA, N.L. 1984. New data on the platform magmatism of Timan in the Baikalian (Upper Proterozoic) tectono-magmatic epoch. Izvestia Vysshikh Uchebnykh Zavedenii. Geologiya i Razvedka. Moskva 11: 110-1.
