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(krā`tŏn): see continentcontinent,
largest unit of landmasses on the earth. The continents include Eurasia (conventionally regarded as two continents, Europe and Asia), Africa, North America, South America, Australia, and Antarctica.
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consolidated parts of the earth's crust that cannot be transformed by alpine-type folding. The German geologist H. Stille subdivided them into uplifted cratons, masses of primarily sialic (Si, Al) composition (the ancient Precambrian platforms or shields of Soviet geologists, which are characterized by a continental crustal structure with a developed “graniticmetamorphic” layer), and submerged cratons, masses with simatic (Si, Fe, and Mg) bases (primarily regions of the ocean floor without the “granitic-metamorphic” crustal layer). The term “craton” was proposed by the Austrian geologist L. Kober and is used extensively in foreign writing.



(central continental craton; in Russian, platforma), one of the main structural elements of the earth’s crust. Cratons are large and relatively stable blocks of the crust, having uniform thickness and measuring several thousand km across. They are characterized by very low seismicity, specific volcanic activity, and a slight topographic relief of the earth’s surface.

The concept of cratons first appeared at the turn of the 20th century in the works of A. P. Karpinskii, E. Suess and G. E. Haug. In 1932, A. D. Arkhangel’skii used the Russian term platforma for the first time in its modern sense to denote a central continental craton. The study of cratons was advanced primarily through the work of the Russian and Soviet scientists Karpinskii, A. P. Pavlov, Arkhangel’skii, N. S. Shatskii, A. L. Ianshin, and A. A. Bogdanov.

Cratons formed by the continental-type crust with a well-developed “granitic” layer some 35 to 45 km thick have an angular and isometric outline and are separated by marginal seams from the adjacent geosynclinal belts or ocean troughs. They gradually develop on the site of previously existing geosynclinal systems as a section of the earth’s crust with high mobility becomes a technically stable crust. A craton’s most characteristic structural feature is its two structural stages. The basement is the lower and more ancient stage and is composed of intensely dislocated metamorphosed and granitized rocks; it represents a formation of the precratonic, or geosynclinal, developmental stage of the earth’s crust. The upper, and younger, structural stage—the cratonic mantle—consists of unmetamorphosed, largely sedimentary rocks that overlie the basement usually horizontally and unconformably. Individual parts of the lithosphere passed from the geosynclinal stage to the cratonic stage at various times in the history of the earth. The formation time of the folded basement determines the craton’s geological age.

Cratons are classified as ancient and young. Ancient cratons were formed during the Precambrian, mostly by the start of the late Proterozoic. Ancient cratons include the Eastern European (Russian), Siberian, North American, Sino-Korean, South China, Indian, African, Australian, and Antarctic platforms. These platforms constitute the cores of the modern continents. Young cratons have a folded base of Paleozoic and, partly, late Precambrian origin. The geosynclinal stage of development of young cratons lasted until the beginning, middle, or end of the Paleozoic era or the start of the Mesozoic era, when the cratonic mantle began forming. Depending on the age of the final deformations of the basement, young cratons are classified as epibaikalian, epicaledonian, and epihercynian; epibaikalian cratons are sometimes grouped with ancient cratons.

Ancient cratons are characterized by a crystalline basement composed predominantly of granites, gneisses, and schists. The basements of young cratons contain moderately dislocated and slightly metamorphosed sedimentary and igneous rocks, with granitic intrusions—if they are present at all—of secondary significance. Such a basement is termed a folded cratonic bases. Young cratons include the plains of Western Siberia, Northern Kazakhstan, the Turan Lowlands, Ciscaucasia, and Western Europe.

The largest structural elements of a craton are shields and platforms. As a result of prolonged uplifting and water erosion, shields are almost completely without sedimentary mantles, and the basement of the craton appears on the surface. Platforms, however, have a thick sedimentary mantle some 3 to 5 km thick and the two-stage structure typical of cratons. After shields and platforms, the most important category of cratonic structures comprises anteclises and synclises. These structures are uplifts and depressions of the basement and sedimentary mantle with very gentle slopes. In addition to these structures there are graben-like depressions, or aulacogens. Arches are smaller, elongated structures measuring 200 to 300 km in length; they consist of chains of local uplifts, or placanticlines, and usually develop over faults of the basement.

The development of continental cratons is determined by the movement of the basement, which causes a general uplifting of the craton. This uplifting is complicated by the ruptures that accompany the formation of aulacogens and by the movements originating in adjacent, actively developing geosynclinal belts. The adjacent geosynclinal belts cause the margins of the craton to be periodically drawn into subsidences; the sediments that accumulate are initially continental detrital materials, followed by coal- or salt-bearing lagoon and shallow-pelagic and sandy-argillaceous carbonaceous formations, and then once more by lagoonal and continental deposits. Periodic activation of tectonic movements, associated primarily with orogenic epochs in geosynclinal belts, lead to partial transformation of cratons into epicratonic orogenic zones; this occurs chiefly on the peripheries of cratons. This is accompanied by an uplifting of the craton and the emergence of a secondary mountainous topography with great height fluctuations. Also related to the epochs of tectonic activation is the revival of magmatic activity on the craton, which, is expressed in the development of specific magmatic formations, including trap (plateau basalts, dikes and sills of dolerites), alkali-basaltic, alkali-ultrabasaltic (ring intrusions), and kimberlite.

The development of cratons is a process that lasts many hundreds of millions of years. The following major stages are distinguished: the genesis, or cratonization, stage, with general uplifting; the aulacogen stage, with the formation of graben-like downwarps; the platform stage, with subsidence, accumulation of a sedimentary mantle, and the formation of synclises and platforms; and the general uplifting stage, with partial washout of the mantle.

In the 1960’s, extensive study of the ocean floor lead to great advances in ideas concerning the global tectonics of the earth. Geologists identified structures within the oceans that are analogous to, but very different from, continental cratons. This led to a new distinction between continental cratons—the subject of all previous research on cratons—and oceanic cratons, or thalassocratons.


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Shatskii, N. S. Izbr. trudy, vol. 2. Moscow, 1964.
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Bogdanov, A. A. [and others]. “Tektonicheskaia nomenklatura i klassifikatsiia osnovnykh strukturnykh elementov zemnoi kory materikov.” Geotektonika, 1972, no. 5.
Khain, V. E. Regional’naia geotektonika: Severnaia i Iuzhnaia Amerika, Antarktida i Afrika. Moscow, 1971.
Khain, V. E. Obshchaia geotektonika, 2nd ed. Moscow, 1973.



A large, stable portion of the continental crust. Cratons are the broad heartlands of continents with subdued topography, encompassing the largest areas of most continents.
References in periodicals archive ?
Cratons started gaining appreciation in the 1970s, when geologists first recognized that the rocks made no outward sense.
It became clear to me that cratons were just about the most puzzling things," says Jordan, of the University of Southern California in Los Angeles.
Though some recent discoveries don't agree with all his forecasts, nearly all papers on the formation and stability of cratons refer to his early studies as seminal.
Although correlation of platformal sequences on dispersed cratons is one of the more definitive tools to track initially adjacent pieces of crust (e.
When a supercraton breaks up, apparent polar wander paths bifurcate; when two cratons are joined by collision, two previously independent paths merge into a common path.
For instance, about half of the mafic magmatic events in the Slave and Superior, two of the best-studied cratons worldwide, remain to be dated precisely.
In addition to the index taxon, Asteridium tornatum (Volkova), the Lontova acritarch assemblage of the East European Craton is characterized by the occurrence of Granomarginata squamacea Volkova, G.
The onset of the trilobite-bearing early Cambrian sediments is restricted to the westernmost marginal area of the East European Craton, where a number of longitudinal gulf-like depressions were formed.
Not only are cratons not covered by water or low-density sediments, but these regions are often being lifted in relation to other parts of the continents.
These researchers used a different set of seismic waves to measure differences between the mantle under cratons and the mantle under oceans.
Crustal thickness in the Canadian Appalachians varies from 45 km beneath the Laurentian craton to 30 to 35 km beneath the Central Mobile Belt (Dunnage and Gander zones), to 40 km beneath the Avalon Zone.
Paleoproterozoic orogenic belts of Canada comprise nearly 6000 kilometres of strike-length orogenic material that record the formation of the core of the taurentian craton between 2.