Eastern European Platform
Eastern European Platform
(also Russian Platform, European Platform), one of the largest, relatively stable areas of the earth’s crust and among the oldest (Preriphean) platforms. It occupies a significant portion of eastern and northern Europe, from the Scandinavian mountains to the Urals and from the Barents Sea to the Black and Caspian seas. The boundary of the platform in the northeast and north passes along the Timan Ridge and the coast of the Kola Peninsula, and in the southwest along a line crossing the Central European Plain close to Warsaw and then running northwest across the Baltic Sea and the northern part of the Jutland Peninsula.
Until the last decade, the northeastern part of the Eastern European Platform was thought to include the area of the Pechora Lowland, the Timan Ridge, the Kanin and Rybachii peninsulas, and the adjacent area of the floor of the Barents Sea; in the northwest, the northern portion of Central Europe (the Central European Plain, the territory of Denmark, the eastern portion of the island of Great Britain, and the floor of the North Sea) were also included in the platform. In recent years, the interpretation of the tectonic nature of the listed areas has been altered due to the fact that the age of the basement within them was determined as Late Proterozoic. Certain researchers (M. V. Muratov and others) have begun to consider these regions as part of the area of Baikalian folding in the adjacent folded zones and thereby to exclude these regions from the limits of the ancient (Preriphean) platform. According to another opinion (A. A. Bogdanov and others), the Baikalian folding only partially reworked the same Preriphean basement of the platform, and on this basis the designated areas continued to be viewed as part of the Eastern European Platform.
The structure of the Eastern European Platform consists of the ancient, Preriphean (Karelian, more than 1.6 billion years old) folded crystalline basement and the sedimentary (Epikarelian) mantle lying conformably on it. The basement is exposed only in the northwest (the Baltic Shield) and the southwest (the Ukrainian Shield) of the platform. On the remaining larger area known as the Russian Plate, the basement is covered with a mantle of sedimentary deposits.
In the western and central parts of the Russian Plate that lie between the Baltic and Ukrainian shields, the basement is relatively uplifted and lies at a shallow depth, forming the Byelorussian and Voronezh arches (anteclises). These arches are separated from the Baltic Shield by the Baltic tectonic depression (syneclise; stretching from Riga in a southwesterly direction) and from the Ukrainian Shield by the system of graben-like depressions of the Dnieper-Donets aulakogene, which includes the Pripiat’ and Dnieper grabens and terminates in the east in the Donets folded structure. To the southwest of the Byelorussian arch and to the west of the Ukrainian Shield, along the southwestern edge of the platform stretches the marginal Bug-Podol’sk Depression.
The eastern part of the Russian Plate is characterized by a deeper occurrence of the basement and by the presence of a thick sedimentary mantle. Here there are two tectonic depressions, the Moscow tectonic depression, which stretches to the northeast almost as far as Timan, and the Caspian tectonic depression (in the southeast), which is bounded by faults. They are separated by the complexly structured Volga-Urals arch. Its basement has been broken up into prominences (the Tokmovo, Tatar, and others) separated by graben-aulokogenes (the Kazan-Sergievsk, Upper Kama). In the east, the Volga-Urals arch is bordered by the marginal deep Kama-Ufa Depression. Between the Volga-Urals and Voronezh arches lies the large and deep Pachelma aulakogene, which in the north merges with the Moscow tectonic depression. Within the latter, at a significant depth from the surface, an entire system of graben-like depressions has been discovered near the bottom, and these depressions stretch in a northeast and northwest direction. The most important of them are the Middle Russian and Moscow aulakogenes. Here the basement of the Russian Plate is located at a depth of 3—4 km, while in the Caspian Depression the basement has the greatest depth of occurrence (16-18 km).
The structure of the basement of the Eastern European Platform is composed of folded, highly metamorphosed sedimentary and magmatic rocks which over great expanses have been changed into gneisses and crystalline schists. In certain areas these rocks are of a very ancient Archean age, older than 2.5 billion years (for example, the White Sea massif, the Ukrainian-Voronezh massif, and the massif in the southwest of Sweden). Between them lie the Karelian folded systems composed of rock of Lower and Middle Proterozoic age (2.6-1.6 billion years). In Finland and Sweden, the corresponding systems are the Svecofennian folded systems; and in western Sweden and southern Norway, the somewhat younger Dalslandian system. As a whole, the basement of the platform, with the exception of the western margin (the Dalslandian and Gothian folded systems) was formed by the beginning of the Late Proterozoic (earlier than 1.6 billion years ago).
The sedimentary mantle contains deposits from the Upper Proterozoic (Riphean) to the Quaternary. The most ancient rocks of this mantle (the Lower and Middle Riphean), represented by consolidated clays and sandstone quartzites, are present in the Bug-Podol’sk and Kama-Ufa depressions, as well as in Finland (Jotnian), Sweden, and Norway (sparagmite), and other regions. In a majority of the deep depressions and aulakogenes, the sedimentary series begin with the Middle and Upper Riphean deposits (clays, sandstones, diabasic lavas, and tuffs), in the Dnieper-Donets aulakogene with Middle Devonian rock (clays, sandstones, lavas, and rock salt), while in the Caspian tectonic depression, the age of the lower portion of the sedimentary cover is unknown. In places the sedimentary series has been disturbed by gentle flexures, by domelike (arches) and elongated (swells) uplifts, and even by faults.
Two major periods have been established in the history of the Eastern European Platform. During the first, which encompasses the entire Archean and the Early and Middle Proterozoic (3.5-1.6 billion years ago), the crystalline basement was formed, while in the second, there occurred the platform development per se and the formation of the sedimentary mantle and the present structure (from the beginning of the Late Proterozoic to the Quaternary).
The minerals of the basement include iron ore (the Krivoi Rog basin, the Kursk magnetic anomaly, and Kiruna), as well as the ores of nickel, copper, titanium, mica, pegmatite, and apatite. The sedimentary mantle contains deposits of combustible gas and oil (the Volga-Urals arch, the Pripiat’ Depression, and the Caspian syneclise), deposits of rock and potassium salts (the Kama-Urals area, the Pripiat’ Depression, and elsewhere), fossil coal (the L’vov, Donets, and Moscow basins), phosphorites, bauxites, deposits of building raw materials (such as limestones, dolomites, and clays), as well as pools of fresh and mineral waters.
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Tektonika Evropy: Ob”iasnitel’naia zapiska k Mezhdunarodnoi tektonicheskoi karte Evropy. Moscow, 1964.
Tektonika Evrazii (Ob”iasnitel’naia zapiska k tektonicheskoi karte Evrazii, m-b 1:5,000,000). Moscow, 1966.
Bogdanov, A. A. “Tektonicheskaia istoriia territorii SSSR i sopredel’nykh stran.” Vestnik MGU: Seriia IV: Geologiia, 1968, no. 1.
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M. V. MURATOV