The Polotsk-Kurzeme and the Småland-Blekinge Deformation Zones of the East European Craton : geomorphology, architecture of the sedimentary cover and the crystalline basement

Abstract: This is a study of the influence of the crystalline basement faults of the Polotsk-Kurzeme and the Småland-Blekinge Deformation Zones on the development of the sedimentary cover and the formation of the present topography. The purpose is to define the character and possible causes of this influence. The key target areas of this study are the Polotsk part of the Polotsk-Kurzeme Deformation Zone in northern Belarus and the eastern part of the Småland-Blekinge Deformation Zone in southeastern Sweden. The influence of Mesoproterozoic faulting on the Paleozoic, Mesozoic, Cenozoic and recent evolutions of the Precambrian crust has been assessed using 3D reconstructions of paleosurfaces, GIS (=Geographical Information Systems) models of basement-cover correlation and topolineaments identification. The 3D upper paleosurfaces of the crystalline basement, the Ectasian-Stenian, Ediacaran, Ordovician, Devonian and Quaternary sedimentary deposits and the present landform surface for the Polotsk key area as well as the 3D upper paleosurfaces of the crystalline basement and the present landform surface for the eastern part of the SBDZ key area have been performed with ArcGis 9.1 software. A series of maps showing correlation coefficients between the upper paleosurface of the crystalline basement and all the various Phanerozoic deposits has been produced for the key target areas. We have also profiled the Quaternary deposits in the Polotsk area. The results suggest that these deformation zones, after their first formation in the Mesoproterozoic in conjunction with orogenic processes at the southwestern margin of the East European Craton were still active during the Neoproterozoic- Phanerozoic. The tectonic activity of the Polotsk-Kurzeme and the Småland-Blekinge Deformation Zones has had influence both on the formation of the sedimentary cover and the present topography.