The Orsha Depression is a negative tectonic structure of the East European platform .
Location
The depression extends to the north and northeast and separates the Belarusian and Voronezh anteclises. A small branch of the Orsha Depression stretches southwest to the city of Cherven and forms the Cherven structural bay. In the east it borders on the Yartsevo buried ledge, in the north through the weakly pronounced Velizh saddle it merges with the Toropetsk-Vyazemsky trough, in the west it joins the Latvian saddle , the Vileika buried ledge of the Belarusian anteclise, in the southeast - with the Surazh buried ledge of the Voronezh angeky - on the south with the Zhlobin saddle , in the south-west - with the Bobruisk buried ledge of the Belarusian anteclise. The length of the Orsha Depression is about 250 km, the width is from 120 to 210 km.
Geological structure and structure
The crystalline foundation within the basin falls from estimates of -0.8 to -1.7 km. It is filled with Riphean and Vendian deposits with a thickness of 1 km or more. Riphean and Lower Vendian formations form the Lower Baikal structural complex. Above are the mid- (over the entire basin) and Upper Devonian (in the east) deposits, which form the Hercynian structural complex . In the south, there are Upper Jurassic , Cretaceous , sometimes Paleogene and Neogene deposits. Quaternary rocks are developed throughout the basin.
As the structural elements of the 2nd order on the basement surface and Riphean deposits within the Orsha Depression, the Vitebsk Mold and the Mogilev Mold are distinguished, separated by a Central Orshan horst . A number of local structures stand out along the surfaces of the crystalline basement, Upper Proterozoic, and Devonian sediments. Most of them are poorly understood. The formation of the Orsha Depression began and ended in the Late Proterozoic ; its development was most intensively manifested in the Riphean. On the surface of the Devonian and overlying sediments, the Orsha Depression is not distinguished. Devonian formations monocline down to the east and make up the western side of the Moscow syneclise . Jurassic, Cretaceous, Paleogene and Neogene sediments sink to the south and form the northern edge of the Pripyat syneclise .
Literature
- Orsha Depression // Republic of Belarus : encyclopedia : in 6 volumes / editorial: G.P. Pashkov [et al.]. - Mn., 2007 .-- S. 611.