NEPHELINE SYENITES OF DIFFERENT ALKALINITY TYPES OF THE ALTAI-SAYAN AREA AND GEOLOGIC CONDITIONS OF THEIR FORMATION
V.N. Dovgal'
Institute of Geology, Siberian Branch of the RAS, 3 prosp. Akad. Koptyuga,
Novosibirsk, 630090, Russia
Keywords: Nepheline syenites, type of alkalinity, zoning, Altai-Sayan area
Pages: 716-724
Abstract
By the example of the Altai-Sayan area, a more detailed classification of nepheline syenites by the type of alkalinity (the degree of their K-Na enrichment) is proposed. Six groups of nepheline syenites have been recognized, which formed under different geologic conditions. Zonal distribution of syenites of different alkalinity types throughout the Siberian craton has been established. The K-richest varieties occur along the craton boundary.
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