XENOGENIC CIRCONS IN A WINDY BELT SECTION AS A SIGN OF CRUST’S CONTAMINATION IN PALEOPROTHEROSIS OF SOUTH-EAST OF THE FENNOSKANDINAN SHIELD
In the study of volcanic-sedimentary structures which were formed at the turn of Archaean and Proterozoic, first of all attention is paid to determining the age of volcanic rocks, as the most informative in geodynamic terms. The Windy belt structure is not an exception, in the context of which two major stages of volcanism are standing out: the first is the Kirich stage and the Windy belt stage which is finishing the section of the structure. U-Pb dating of volcanic rocks revealed the participation of crustal matter with an average age of 2.85 billion years in the formation of the Windy belt section.