Belomorian Eclogite Province Research Articles

Dating of key events in the Precambrian polystage complexes: An example from Archaen Belomorian Eclogite Province, Russia

The identification of discrete tectono-thermal events, their sequence, and absolute age is a difficult problem in the highly deformed polymetamorphic Precambrian complexes. The Archean and Paleoproterozoic eclogites are distinguished in the Gridino eclogitebearing melange [1]. Archean eclogites are small equant and elongated boudins and lenses in the granite gneiss matrix and have a U–Pb age of ~2.7 Ga [2]. They are considered a metamorphic product of the Archean oceanic protolith [1]. The Paleoproterozoic eclogites are represented by undeformed and deformed (folded, boudined) eclogitized dikes of different age complexes. They are compositionally similar to the Archean eclogites and, in addition to the Archean zircons, contain Paleoproterozoic zircons with an age ~2.45–2.42 Ga. All mafic bodies (dikes of different generations and boudins) were subsequently overprinted by eclogites, high-grade granulite, and amphibolite-facies events (Fig. 1).