Zirconology of Calcite Carbonatite of the Vishnevogorsk Massif, Southern Urals

摘要

The dating 419 ± 20 Ma (Late Silurian) corresponds to the initial stage of evolution of the Vish-nevogorsk carbonatite accompanied by alteration of early zircons whose maximum age (439 ± 2.8 Ma, crystal 6, table) determines the minimum age of the carbonatite substratum. The relation of carbonatite torncontinental riftogenesis is suggested [7]. Similar zircons from miaskite of the ll'meny massif are dated at 417.5 ±7.5 Ma [11].