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The Buntsandstein (German for ''coloured'' or ''colourful sandstone'') or Bunter sandstone〔Dickinson, Robert E. (1964). ''Germany: A regional and economic geography'' (2nd ed.). London: Methuen. .〕 is a lithostratigraphic and allostratigraphic unit (a sequence of rock strata) in the subsurface of large parts of west and central Europe. The Buntsandstein predominantly consists of sandstone layers of the Lower Triassic series and is one of three characteristic Triassic units, together with the Muschelkalk and Keuper that form the Germanic Trias Supergroup. The Buntsandstein is similar in age, facies and lithology with the Bunter of the British Isles. It is normally lying on top of the Permian Zechstein and below the Muschelkalk. In the past the name Buntsandstein was in Europe also used in a chronostratigraphic sense, as a subdivision of the Triassic system. Among reasons to abandon this use was the discovery that its base lies actually in the latest Permian. ==Origin== The Buntsandstein was deposited in the Germanic Basin, a large sedimentary basin that was the successor of the smaller Permian Basin and spread across present day Poland, Germany, Denmark, the southern regions of the North Sea and Baltic Sea, the Netherlands and south England. In the late Permian this region had an arid climate and it was covered by inland seas which deposited the Zechstein evaporites. At the end of the Permian a connection with the Paleo-Tethys Ocean to the south was formed in present-day southeast Poland, causing sea water to flow in periodically. This caused the inflow of more clastic material, which was deposited in the form of large alluvial fans. Deposition took place in an arid, continental environment (playa facies), so that there was little chemical weathering. Therefore, the Bundsandstein deposits are typical red beds, mainly sandstones and conglomerates with little clay. The late Anisian saw a major rise of the global (eustatic) sea level. A tropical sea filled the Germanic Basin then, stopping the deposition of the Buntsandstein and marking the beginning of the deposition of the Muschelkalk. 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「Buntsandstein」の詳細全文を読む スポンサード リンク
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