Abstract

The Devonian is widely developed throughout the Russian platform with the exception of uplifted parts of the Baltic Shield, the Voronezh and Ukrainian crystalline rock masses, the Timan range, and some other regions. These Devonian beds crop out on the slopes of all the above mentioned tectonic features. Their thickness ranges from 0 to 2000 metres.

Lower Devonian beds have a limited distribution. They occur in the west, southwest and southeast parts of the platform, and are represented mainly by terrigenous rocks.

The Middle Devonian is represented by the Eifelian and Givetian stages. The Eifelian Stage is made up of sandy-clayey rocks in the lower part, and by calcareous rocks in the upper. The Givetian Stage is represented by terrigenous deposits with calcareous interlayers. The Upper Devonian includes both the Frasnian and the Fammenian stages. The Frasnian Stage is made up of sandy-clayey rocks in the lower part and of clayey rocks in the middle, while its upper portion as well as the Famennian Stage is represented by calcareous rocks.

Among economic deposits, oil and gas fields occur mainly in the Volga-Urals and in the Timan-Pechora oil and gas bearing regions, where they are confined chiefly to terrigenous deposits of Middle and Late Devonian age. In the Pripyat depression, petroliferous deposits are located in calcareous Upper Devonian strata, as are deposits of potash salt.