ON PHYSICAL PROPERTIES OF THE TECTONOSPHERE OF THE BELARUS-BALTIC REGION
V.N. ASTAPENKO, G.I. KARATAYEV
In recent years complex geophysical investigations have been carried out in the Belarus-Baltic Region along the profiles Riga-Vitebsk-Bobruysk-Slonim-Sovetsk-Riga and Grodno-Vitebsk. These profiles intersect the main tectonic zones of the region as well as crustal blocks of various deep structure. These series of measurements of the annual increment of gravitational and magnetic fields 20-40 km spaced and magnetotelluric sounding along these profiles have been made in four recent years. The data obtained have made it possible to construct the curves of anomalous annual values of gravitational and magnetic fields and a telluric section of the t4ectonosphere of this region. The comparison of these results with the data on the Earth„s crust types allows a conclusion that the deep faults in the crystalline basement dividing crustal blocks of various types are evidently shown by high gradient of the curves of anomalous annual values of gravitational and magnetic fields as well as by ruptures in the crustal layers with high conductivity. The curve of anomalous annual values of gravitational and magnetic fields is tending to decrease in a transition from crustal blocks showing high thickness of the crust and thick "basaltic" layer and basic rock composition to those with rather thin crust and "basaltic" layer and composed of intermediate rocks. The anomalies of the annual values of gravitational and magnetic fields can be correlated with the Kurzemsk-Polotsk fault zone which confirms its modern tectonic activity.
The telluric section of crustal blocks composed of basic rocks and of intermediate rocks differ from each other. In the former case, the telluric section show relatively high conductivity of the crust as a whole which insignificantly varies with depth.