Abstract

Devonian deposits (Givetian, Frasnian and Famennian Stages), are widespread in Byelorussia, where their thickness is from some tens of metres to 4000-5000 metres.

The deposits of the Givetian Stage have a thickness of up to 200-300 metres and consist of the Pyarnus, Narovsk and Starooskol horizons. The Pyarnus-Narovsk Horizon is composed of sandy deposits in its lower part and of dolomite, marl and clay above. In places, the horizon contains beds of anhydrite and salt. The Starooskol horizon is composed of arenaceous deposits and aleurolite in the lower part and of aleurolite and clay in the upper.

The Frasnian section in the Orsha depression is incomplete. Its thickness is not very great (up to 100 metres) and consists of carbonate deposits. In the Pripyat depression the thickness is much greater (over 100 metres). Here the deposits consist of terrigenous and clayey materials in the lower part (Lower Schigrovsk horizon), of carbonate deposits in the middle (Upper Schigrovsk, Semiluk, Patchin, Voronezh horizons and the lower part of Evlanov horizon) and of evaporites in the upper part of the section (the upper part of the Evlanov and Liven horizons). Evaporite deposits are replaced by carbonates in the western part of the depression.

Famennian deposits are present only in the Pripyat depression. They have a thickness to 2000-4000 metres and consist of clay material, carbonate and terrigenous deposits in the lower part (Zadonsk horizon). In the middle part they are represented by evaporite deposits (Eletsk and the lower part of the Lebedyan horizon) and by terrigenous, carbonate and clay deposits in the upper part (the upper part of Lebedyan and the Dankov horizons).

The Devonian stratigraphy of Byelorussia has been studied on the basis of data which have been obtained while studying the flora and fauna, the lithology, and the geophysical aspects.

The widespread occurrence of volcanic rocks is a characteristic feature of Devonian deposits in the Pripyat depression. Active epigenetic processes must be taken into consideration in any study of the problems of stratigraphy and sedimentation.

Of economic interest are beds of halite and potash salts, coals and shale, as well as oil accumulations and mineral and thermal waters in the Pripyat depression.