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A craton (, , or ;〔http://www.oxforddictionaries.com/us/definition/american_english/craton 〕〔http://www.oxforddictionaries.com/definition/english/craton〕 from (ギリシア語:κράτος) ''kratos'' "strength") is an old and stable part of the continental lithosphere. Having often survived cycles of merging and rifting of continents, cratons are generally found in the interiors of tectonic plates. They are characteristically composed of ancient crystalline basement rock, which may be covered by younger sedimentary rock. They have a thick crust and deep lithospheric roots that extend as much as several hundred kilometres into the Earth's mantle. The term ''craton'' is used to distinguish the stable portion of the continental crust from regions that are more geologically active and unstable. Cratons can be described as shields, in which the basement rock crops out at the surface, and platforms, in which the basement is overlaid by sediments and sedimentary rock. The word craton was first proposed by the Austrian geologist Leopold Kober in 1921 as ドイツ語:''Kratogen'', referring to stable continental platforms, and ''orogen'' as a term for mountain or orogenic belts. Later authors shortened the former term to ''kraton'' and then to ''craton''. Examples of cratons are the Slave Craton in Canada, the Wyoming Craton in the United States, the Amazonia Craton in South America, the Kaapvaal Craton in South Africa, and the Gawler Craton in South Australia. == Provinces == Cratons are subdivided geographically into geologic provinces. A geologic province is a spatial entity with common geologic attributes. A province may include a single dominant structural element such as a structural basin or a fold belt, or a number of contiguous related elements. Adjoining provinces may appear similar in structure but be considered separate due to differing histories. (Note that the term "geologic province" can have several different meanings, depending on context.) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「craton」の詳細全文を読む スポンサード リンク
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