stripes
Sallanlatvi is the most westerly member of an east-west-trending group that includes the occurrences of Vuoriyarvi and Kovdozero. The complex is a concentrically zoned intrusion with an area of about 9 km2. It comprises three major zones which from the periphery towards the centre decrease in age and are composed respectively of melteigite, urtite-ijolite and carbonatite. The width of the peripheral zone varies from 100-200 m in the north to 600-800 m in the west. The melteigites are fine-grained and characterised by a fluidal layered structure, which dips towards the centre of the complex. These rocks are gradually replaced by banded ijolites with nests and vein-like bodies of urtite, with in the western part of the inner zone the urtites becoming predominant. In the same part of the complex numerous arcuate bodies of ijolite pegmatite enriched in apatite and schorlomite occur, which are traceable along the strike for up to 200 m, the thickness varying from 0.5 to 2 m. Carbonatites make up the central part of the massif, which also has a zonal structure. The outer ring, which is rather narrow, is composed of a series of closely spaced, steeply-dipping veins and irregular, possibly lens-shaped, bodies of calcite carbonatite with relicts of silicate rocks which have been much replaced by mica. The central part of the carbonatite zone is composed of dolomite-ankerite or dolomite-siderite carbonatites. Calcite carbonatites also form independent veins in the ijolite-urtite and ijolite-melteigite zone of the massif. They are similar in composition to the carbonatites of the ring. There are blocks (0.5-1.5 m diameter) of pyroxenites, much replaced by mica, among the carbonatites of the central core; the pyroxenites are injected by ijolite. All rocks, including the carbonatites, are intersected by thin dykes of monchiquite. The calcite carbonatites of the ring-shaped zone and veins contain 75-80% calcite together with natrolite, cancrinite, phlogopite, aegirine-diopside and secondary chlorite. The accessories include apatite, titanite, magnetite, zircon, pyrochlore, hydroxyapatite, ancylite and parisite. The dolomite-ankerite carbonatites also contain dolomite, rhodochrosite and baryte in the crust of weathering; they are also enriched in hematite, psilomelane, pyrolusite, aragonite and strontianite. Accesories are represented by magnetite, ilmenite, ancylite, parisite, pyrochlore, and an abundance of sulphides of which pyrite, sphalerite and arsenopyrite are typical.
KUKHARENKO, A.A., ORLOVA, M.P., BULAKH, A.G., BAGDASAROV, E.A., RIMSKAYA-KORSAKOVA, O.M., NEPHEDOV, E.I., IL'INSKII, G.A., SERGEEV, A.S. and ABAKUMOVA, N.B. 1965. The Caledonian complex of ultrabasic alkaline rocks and carbonatites of the Kola peninsula and north Karelia. Nedra, Moscow. 772 pp.
ORLOVA, M.P. 1963. Some questions of petrochemistry and petrology of the Caledonian complex of alkaline ultrabasic rocks of the Kola Peninsula. All-Union Scientific Research Geological Institute, New Series, 96: 18-41.
