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(1) A long, relatively narrow and deep trough in the earth’s crust within a geosynclinal belt. It may extend for tens or hundreds of kilometers. It is found on the bottom of marine basins and is usually bounded by faults and filled with thick strata of sedimentary and volcanic rock. As a result of intensive tectonic deformations over a long period of time it is transformed into a complex folded formation that is part of a mountain structure (A. D. Arkhangel’skii, N. S. Shatskii, N. A. Shtreis, M. V. Muratov).
(2) A vast, linearly elongated, tectonically mobile segment of the earth’s crust within which particular geosynclinal troughs (geosynclines in the first sense) originate and develop and also are transformed into complex folded mountain structures. It is also called a geosynclinal belt (M. M. Tetiaev, V. V. Belousov, the French geologist J. Auboin).
The term geosyncline in its first sense was initially used by the American geologist J. Dana (1873), although a similar concept was advanced earlier, in 1859, by the Scottish geologist J. Hall, with respect to the Appalachians. In 1900 the French geologist E. Haug clearly distinguished between geosynclines and continental areas with a stable bedding of layers, known as platforms. Haug and the Swiss investigators of the Alps showed that geosynclines have a complex internal structure and are broken up into individual troughs by uplifts (geoanticlines) during their development. The German geologist E. Kraus outlined the main stages in the development of geosynclines. The American geologist C. Schuchert proposed the first classification of geosynclines, and his compatriot A. Grabau advanced the theory of their migration. The German geologist H. Stille drew some general conclusions about geosynclines and described the connection between the development of geosynclines and the manifestation of magmatic processes. He proposed the distinction between eugeosynclines and miogeosynclines, depending on the intensity of these processes. Beginning in the 1930’s Soviet geologists were actively involved in the study of geosynclines. In 1933, A. D. Arkhangel’skii introduced the concept of geosynclinal regions. In 1938-40, V. V. Belousov clarified certain important general aspects of the development of geosynclines, using the Caucasus as his initial example. In 1945, A. V. Peive introduced the notion of deep faults which play a very important part in the initial stage of subsidence and in the further evolution of geosynclines. In 1947, N. S. Shatskii showed that geosynclines are grouped into geosynclinal systems, which are distinguished by their unique developmental histories. M. V. Muratov and V. E. Khain proposed classifications of the structures of geosynclinal series and refined the stages of their development. A significant contribution to the working out of questions related to the concept of the geosyncline has also been made in recent decades by foreign scientists, including the American geologist G. M. Kay and J. Auboin. Thus, from the initial conception of geosynclines as unique troughs in the earth’s crust there has gradually developed a theory of geosynclines, which is one of the most important conclusions of theoretical geology. The theory of geosynclines is the nucleus of a broader theory of the evolution of the structure of the earth’s crust as a whole.
REFERENCESPeive, A. V. “Glubinnye razlomy v geosinklinal’nykh oblastiakh.” Izv. AN SSSR: Seriia geologicheskaia, 1945, no. 5.
Shatskii, N. S. “Gipoteza Vegenera i geosinklinali.” Izv. AN SSSR: Seriia geologicheskaia, 1946, no. 4.
Arkhangel’skii, A. D. Geologicheskoe stroenie i geologicheskaia istoriia SSSR, 4th ed., vols. 1-2. Moscow-Leningrad, 1947-48.
Muratov, M. V. “Tektonika i istoriia razvitiia Al’piiskoi geosinklinal’noi oblasti iuga Evropeiskoi chasti SSSR i sopredel’nykh stran.” In the collection Tektonika SSSR, vol. 2. Moscow-Leningrad, 1949.
Peive, A. V., and V. M. Sinitsyn. “Nekotorye osnovnye voprosy ucheniia o geosinklinaliakh.” Izv. AN SSSR: Seriia geologicheskaia, 1950, no. 4.
Kay, M. Geosinklinali Severnoi Ameriki. Moscow, 1955. (Translated from English.)
Khain, V. E., and Iu. M. Sheinmann. “Sto let ucheniia o geosinklinaliakh.” Sovetskaia geologiia, 1960, no. 11.
Belousov, V. V. Osnovnye voprosy geotektoniki, 2nd ed. Moscow, 1962.
Bogdanov, A. A., M. V. Muratov, and V. E. Khain. “Ob osnovnykh strukturnykh elementakh zemnoi kory.” Biull. Moskovskogo obshchestva ispytatelei prirody: Otdel geologicheskii, 1963, vol. 38, no. 3.
Muratov, M. V. “Strukturnye kompleksy i etapy razvitiia geosinklinal’nykh skladchatykh oblastei.” Izv. AN SSSR: Seriia geologicheskaia, 1963, no. 6.
Stille, H. Izbr. trudy. Moscow, 1964. (Translation from German.)
Khain, V. E. Obshchaia geotektonika. Moscow, 1964.
Muratov, M. V. “Glavneishie epokhi skladchatosti i megastadii razvitiia zemnoi kory.” Geotektonika, 1965, no. 1.
Muratov, M. V. “Skladchatye geosinklinal’nye poiasa Evrazii.” Geotektonika, 1965, no. 6.
Tektonika Evrazii. Moscow, 1966.
Auboin, J. Geosinklinali: Problemy proiskhozhdeniia i razvitiia. Moscow, 1967. (Translated from English.)
V. E. KHAIN, M. V. MURATOV, and E. V. SHANTSER