The First Discovery of Pseudotachylytes in the Paleoproterozoic Ladoga Zonal Metamorphosed Complex of Fennoscandia and Their 40Ar/39Ar Dating.

The results of 40Ar/39Ar dating of pseudotachylytes, first identified in the Paleoproterozoic zonally metamorphosed (greenschist to granulite facies) Ladoga complex of svecofennides, are presented. A wide age range of the formation of pseudotachylytes in the Riphean (1.59–1.31 Ga), presumably caused by the exhumation of deep rocks during the Svecofennian tectonogenesis and the subsequent orogenesis and riftogenesis in southeastern Fennoscandia, has been established. [ABSTRACT FROM AUTHOR]