Основные морфоструктурные особенности допалеогенового фундамента Верхнефракийской депрессии и его осадочного чехла

Abstract

The results of the detailed geologo-geophysical research in the Upper Thracian Depression are presented. Original geologo-structural map is drawn up in scale- 1:100 000, revealing Pre-Paleogene basement relief. The existing of the generalized longitudinal blocky structures - Stryama-Harmanli horst and Momino-Marbas-Sokolitza trough, is proved. The Maritza trough is extended south-eastwards and it is suggested, that during the Paleogene wider negative depression region, including in the area of Upper Thracia the north-western parts of the contemporary Borovishka volcano structure of the East Rhodopes depression , has existed. The concept for the existing of the so-called "Chirpan step" as elevated cross blocky structure in the Pre-Paleogene basementis is not confirmed. The relative tectonic independence of the Plovdiv and Zagora depressions and their entity in the structure of the Upper Thracian Depression is reflected as a result of the development and the interaction of the regional deep fault as early as the Upper Cretaceous time. The regularities in the disposition of terraced and mosaic small block structures from higher rank are determined. Maps of the isothickness of the Paleogene and Neogene and maps of the upper boundary relief of the Paleogene are drawn up. They give a complete idea for the inner structure of the Upper Thracian Depression. For the predominant part of the studied area the Neogene inherits the direction of the tectonic movements of the Paleogene . Separate sections with diverse direction of the vertical movements, as well as with horizontal slip fault and left rotation shifting are delineated. It is suggested, that the Late Alpine tectonic of the region is controlled by the basic longitudinal structural elements of the PrePaleogene basement. The received largescale pattern about the geological and lithostratigraphic evolution of the separate fault-blocky structures enables to assert that the block-stratified structure is typical for the upper part from the section of the earth crust in the Upper Thracian Depression.