Abstract
Eclogites in the Gridino complex of the Belomorian province have complex history of metamorphic transformations. Their polymetamorphism is revealed from relics of early and late high-pressure mineral assemblages (omphacite+garnet), reaction microstructures, changes of the garnet chemical zoning, results of thermobarometric calculations, and isotope-geochronological studies. Geochronological data indicate two stages of eclogitic metamorphism in the Gridino complex at the Archean and Paleoproterozoic. As a result of the study, we obtained two P-T-t trends for the regressive stage of rock evolution with a successive transition from eclogitic facies to granulite (amphibolite). The peak of the first metamorphic event responds to metamorphic zircons with an age of 2,7 Ga. The maximal values of the P-T conditions of the second metamorphic event are reliably correlated with 1,9 Ga metamorphic zircons.
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