PALEO-VALLEYS AND RECONSTRUCTION OF RIVER VALLEY NETWORK IN THE MOESIAN PLATFORM, NORTH BULGARIA
Доклади на БАН, Comptes rendus de l'Academie bulgare des Sciences
Tome 65, No 12, 2012, 1725-1730, ISSN 1310–1331 (Print), ISSN 2367–5535 (Online)
In this article the stages of origin, deepening of river beds, fossilization, reconstruction and last forming of river valley network in the Moesian Platform are traced.
During the first stage (Priabonian − Middle Miocene) under the conditions of droughty erosion-denudation cycle in the south segment of the Platform is formed a denudation surface, divided by submeridional pre-Badenian valley vertical deformations of river beds. Its correlative Oligocene-Early Miocene sediments are accumulated in the borders of South-Carpathian depression.
In the Middle-Early Pliocene cycle (Badenian-Dacian) the Carpathian folding-thrust orogenic arc lifts up as a result of a powerful compressional stress. The process of compression causes folding and thrusting of the Carpathian orogenic arc on the Pre-Carpathian margin depression. This process gives rise to inrush of the sea basin southward, which on its turn causes fossilization of the paleo-valley shear zones in the borders of the Moesian Platform.
New compression stress takes place in the Carpathian orogenic arc in NE-SE direction during Quaternary. Processes of folding and normal and reverse thrusts are realised. In the Sub-Carpathian depression a sedimentary cross-section with thickness of over 2000 m is formed. The localization and decrease of regional erosion basis determines the reconstruction or the orientation of river valley network from north-northwest to southeast direction having pronounced right asymmetry.
Moesian platform, structural geomorphology, paleoriver-valley network, geomorphological processes
Природни науки, математика и информатика
Natural sciences, mathematics and informatics