Structure and Evolution of the Belomorian–Severodvinsk Shear Zone in the Late Proterozoic and Phanerozoic, East European Platform

Аннотация

The tectonics, morphological features, and development stages of the Belomorian‒Severodvinsk shear zone (northwestern 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 the Paleoproterozoic structures of the Belomorian‒Lapland mobile belt and Riphean grabens of the White Sea rift system. The Belomorian‒Severodvinsk zone was represented in the recent structure by a system of neotectonic grabens limited by normal faults and oblique-slip faults and segmented by transform fault zones. We came to the conclusion that the shear zone experienced multiple repeated activation in different dynamic conditions in the Riphean–Phanerozoic. Cyclic alternation of rift-related transtension and compression or transpression conditions in the sequential stages of its development was noted. We defined three cycles of transtensive‒transpressive transformations of the Belomorian‒Severodvinsk shear zone in the Riphean and the Early Vendian. At least four times the shear zone underwent changes in the deformation mode and shear displacement directions in the Phanerozoic. Postglacial neotectonic deformations in the Belomorian‒Severodvinsk shear zone were revealed under the horizontal SE movement and subsequent counterclockwise rotation of the Kola Block.