Lithospheric structure along a profile from the Black Sea to the Polar Urals

Abstract

A crustal section from the Black Sea to the Polar Urals, more than 3500 km long, has been obtained from the results of explosion seismology surveys, conducted with a variable density of observation coverage and using different types of seismic waves. At the southern end of the profile, within the Black Sea basin, the observations were single refraction soundings, in the Crimia and the Ukrainian crystalline massif, continuous profiling with correlation systems of primarily reflected waves, in the Voronezh crystalline massif and within the southern slope of the Moscow basin, systems of reversed and overlapping refraction shooting and further to the northern end of the profile, systems of single soundings using refracted and reflected waves and S-P conversions. The section details the crustal structure of the Black Sea depression, of the Scythian platform in the Crimea peninsula and of the major structural features of the eastern part of the European platform, such as the Ukrainian and Voronezh massifs, Dnieper-Donetsk and Pachelmsky aulacogens, Moscow and Pechora syneclises, Timan uplift and Karatakhin foredeep in the Polar Urals. The thicknesses of the crustal layers, distribution of lowvelocity layers in the crust and lateral velocity variations indicate that the above-mentioned structural features extend throughout the whole of the crust. Therefore they may be classified as structures of abyssal origin related to the formation of the tectonosphere. The crustal structure also reflects structural features of the consolidated basement of the sedimentary cover of the European platform composed of Archean and Lower Proterozoic series of crystalline schists and gneisses. The analysis of the relations between the topography of the basement, sedimentary cover and crustal discontinuities including that of Mohorovicic reveals that the crust in the east of the European platform was formed in the Precambrian or Early Phanerozoic and the Scythian platform and Black Sea depression in the Phanerozoic.