COMPOSITION OF MELT INCLUSIONS AND AGE OF ZIRCONS FROM PLAGIOGNEISSES OF THE ARCHEAN COMPLEX IN THE KOLA SUPERDEEP BOREHOLE, BALTIC SHIELD

Abstract

The origin of zircon is of great importance for the petrological interpretation of U–Pb dates. Direct information on the magmatic origin of zircon from intensely metamorphosed Archean rocks is provided by findings of primary melt inclusions. At the same time, not even detailed structural–morphological investigations are sufficient to decipher the relict-magmatic or later anatectic origin of zircon with melt inclusions. The timing of melt entrapment must be established for the reliable identification of these genetic types.