Formation of eudialyte-bearing phonolite from Kontozero carbonatite paleovolcano, Kola Peninsula

The results of the geological and petrologic study of eudialyte-bearing phonolite from the Late Devonian Kontozero carbonatite paleovolcano are discussed in the paper. This eudialyte-bearing phonolite corresponds to the primary melt derived from the metasomatized upper mantle source composed of phlogopite-amphibole eclogite. The average ZrO₂ content in the Kontozero phonolite (1.02 wt %) is considered to be cotectic (Kogarko et al., 1988). Similar REE patterns of the Kontozero eudialyte-bearing phonolite and porphyritic lujavrite from the chilled contact zone of the Lovozero eudyalite complex and close REE and Zr concentrations in the compared rocks show that this complex could have been formed from a melt similar in composition to the phonolite melt of Kontozero.