Junction of deep structures of the Carpatho-Balkan region with those of the Black and Adriatic Seas

Abstract

Deep crustal structures have been studied on the territory of southeastern Europe by means of deep seismic soundings (DSS), and a topographic scheme of the Mohorovičić (Moho) discontinuity has been compiled.Crustal thickness varies from 20–25 km in the Black Sea Depression and the Pannonian Middle Massif to 50–55 km in the Crimea, Carpathians, and Dinarides. Mountain 'roots' have been revealed along the Moho discontinuity and 'antiroots' along the 'basaltic' layer surface in the highland areas. Different relationships between the Moho discontinuity and the Conrad and basement surfaces are established, from the conformable to the inverse. Different types of crust are distinguished, characterized by different thicknesses of the individual layers as well as by deep fractures causing a block structure.The depressions of the Black and Adriatic Seas are characterized by the presence of intensive positive gravity anomalies, which are due to zones of subcrustal substance of higher density and thinning of the crust owing to a smaller thickness of the 'basaltic' or 'granitic' layers. The smaller thickness of the crust or its individual layers is associated with vertical and horizontal movements of the crust, which had resulted in over-thrusts, overthrust sheets, etc.The earth's crust of a continental type is contiguous with a sub-oceanic crust of the Black and Adriatic Seas along the deep fractures. The main fracture in the Black Sea is found near the south coast of the Crimean Peninsula, and the second one in the zone of a wedging out of the 'granitic' layer. The crustal region between these fractures should be related to an intermediate type.