Structure and evolution of Belomorian-Severodvinsk shear zone in the Late Proterozoic and Phanerozoic, East-European Platform

Abstract

Tectonics, morphological features and development stages of Belomorian-Severodvinsk shear zone (north-western part) found in the East European platform are considered. We traced the shear zone (length ≈1000 km) from NW to SE from the Baltic shield to the Russian plate sedimentary cover. It inherited Paleoproterozoic structures of Belomorian-Lapland mobile belt and Riphean grabens of the White Sea rift system. Belomorian-Severodvinsk zone was represented in the modern structure by a system of neotectonic grabens limited by normal and normal–strike sleep faults and segmented by the transform fault zones. We came to conclusion that the shear zone experienced multiple repeated activation in different dynamic conditions in the Riphean–Phanerozoic. Cyclic alternation of riftogenic trans-tension and compression or transpression conditions in the sequence stages of its development was noted. We defined three cycles of transtensive-transpressive transformations of Belomorian-Severodvinsk shear zone in the Riphean and the Early Vendian. At least four times shear zone suffered changes of deformation mode and directions of shear displacement in the Phanerozoic. The postglacial neotectonic deformations in the Belomorian-Severodvinsk shear zone revealed under the Kola block horizontal movement to the S–E and subsequent counterclockwise rotation.