LITHOSPHERE, 2002, No. 16, p. 18

Early (Riphean) paleorifts are widespread in the western and central parts of the East European platform. These basins are infilled with a cataplatform cover, which involves the Dalslandian and Lower-Baikalian structural complexes.

The Dalslandian complex is represented by three formations, which replace one another in vertical direction. These are red-coloured arkosic-gravel-sandy, volcanic-gravel-sandy and red-coloured quartz-sandy formations. The first and second ones formed under rifting regime (Ladoga and Krestsy grabens and Sherovichi de-pression). The latter was probably deposited under conditions of a slowly subsiding vast depression. The fragments of this formation are preserved in the Orsha depression, Moscow graben and Pachelma aulacogen.

The Lower-Baikalian complex fills in an extended Volyn-Central Russian depression system and Pachelma aulacogen. The complex is divided into two structural stages. In the Volyn-Central Russian depression system they are represented by two horizontal associations of formations. Every formation was deposited under specific paleogeographical and paleotectonic conditions. However, each structural stage shows common structural features. At the lower stage the clastic material becomes coarser upwards. On the contrary, at the upper stage it becomes thinner in the same direction.

In the Pachelma aulacogen the Lower-Baikalian structural complex is divided into two formations which vertically replace one another. There is some similarity in the structure and rock composition of the Lower-Baikalian deposits of the Pachelma aulacogen and Volyn-Centralrussian depression system.

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