Main Features of the Devonian History of the USSR

Abstract In the territory of the USSR throughout the Devonian there existed the Russian and Siberian platforms and the following geosynclines: Caucasian geosyncline, which extended into the Trans-Caspian region; Uralian geosyncline on the site of the present eastern slope of the Urals, plus the western part of the West Siberian lowland, connected in turn with the Tien Shan geosyncline south of the Aral Sea; Ob-Zaisan geosyncline, which extended in a meridional direction into the middle part of the West Siberian lowland; Jungar-Balkhash geosyncline; Mongolo-Okhotsk geosyncline, coming within the boundaries of the USSR in its northern part; Verkhoyana-Chukotskaya geosyncline with a number of large median masses; Taimyr geosyncline. The Altai-Sayan and Kazakhstan Caledonian folded belts were transitional areas from orogens to platforms. Palaeogeographical reconstructions for early periods of the geological history of the USSR were made on the basis of lithologic-facies and bio-geographical studies and including geophysical data. A special study of palaeomagnetic properties of rocks was also carried out, which permitted a reconstruction of the position of the magnetic poles and a plotting of the magnetic parallels for each period. The climatic zones so reconstructed agree in the main with the palaeogeographical data.