New Data on the Age of Eclogites from the Belomorian Mobile Belt at Gridino Settlement Area

摘要

The repeated isotopic and geochemical study of zircons of the eclogite from Stolbikha Island (Gridino settlement area) allows one to interpret the U—Pb age value of about 2700 Ma by central parts of zircon grains as a magmatic event time, probably rejuvenated to a degree by intense manifestation of the eclogite metamorphism of about 1880 Ma age. The Svecofennian high-pressure metamorphism caused a partial recrystallization of zircons of magmatic origin and the appearance of their rims showing typical geochemical characteristics of eclogite zircons.