Buntsandstein

The red sandstone is the lower lithostratigraphic group of the Germanic Triassic in geology. The term sandstone is somewhat confusing; he does not describe any specific rock type (ie, a colorful colored sandstone), but usually a several hundred meter thick rock unit that is made ​​up predominantly of sandstones. Earlier, the red sandstone (and the shell ) was also regarded as a time unit or time interval of Earth's history and sometimes also referred to as a triad. However, the sandstone is relatively and absolutely in time a very different and therefore can not be used as an internationally usable time interval for the subdivision of the Triassic. The present border Unter-/Mitteltrias does not match the sandstone / limestone boundary agreement, but is somewhat lower (or even starts in the new red sandstone ). Therefore, the sandstone should be construed only as a rock unit ( = unit of lithostratigraphy ) today. The sandstone is on the rock unit of the Zechstein; the lithostratigraphic unit of red sandstone follows the rock unit of the shell.

History

The term sandstone (in the sense of " colorful sandstone " as opposed to " red sandstone " = Rotliegend ) goes back to Abraham Gottlob Werner, who used it from about 1780 in his lectures at the Mining Academy in Freiberg. 1834 with the establishment of the system of the Triassic by Friedrich August von Alberti, the term was already widely recognized as " Bunter sandstone ". Since the 1990s, the red sandstone is considered as a group within the meaning of the lithostratigraphic hierarchy and divided into formations, the boundaries and position relative to other formations are well defined. Alternatively, the Allostratigraphie divides the red sandstone sequences, but whose boundaries coincide in this case with the formations of red sandstone. Allostratigraphie and lithostratigraphy are some different methods to identify a subdivision of rock units.

Definition

The lower limit of the Buntsandstein (and thus also the border of the Germanic Triassic supergroup ) is defined in the basin center with the onset of Calvörde sequence. In the Spessart and Odenwald, the lower limit of the Buntsandstein is defined by the lower limit of Heigenbrucken - sandstone. In the Black Forest, the lower limit of the new red sandstone at the base of the so-called ( Lower ) Eck'schen is placed conglomerate. The upper limit (and thus at the same time, the lower limit of the shell limestone ) is the basis of so-called Grenzgelbkalkes. The lower limit of the sandstone is dated to the areas with very early onset sedimentation already in the top Changhsingium, the top of the Permian chronostratigraphic stage. The upper limit (and therefore the lower limit of the shell ) falls in the lower Anisian, the lowest chronostratigraphic stage of the Middle Triassic. After Stratigraphic map of Germany geochronological it corresponds to the period 251-243 million years ago.

The rocks of red sandstone composed predominantly of continental deposits, such as red conglomerates, sand - and mudstones. Characteristic of the upper sandstone is in the North German gas provinces the Rötsalinar with several tens of meters thick. These evaporites are evidence of a widespread marine influence. The sandstone sequence in Central Europe extending from France (Alsace ) and Luxembourg ( Gutland ) in the west to Poland and Belarus to the east, and from the south of Switzerland to Scandinavia in the north. In the Southwest German cuesta land of red sandstone is revealed on the eastern flank of the Black Forest and in the eastern Odenwald. In the Beck Center in southern Lower Saxony and North Hesse widths are achieved up to about 1000 m.

Structure

The sandstone is placed in the hierarchy of the lithostratigraphy of the rank of a group within the supergroup of the Germanic Triassic. The red sandstone group is divided into three subgroups ( Lower, Middle and Upper Buntsandstein ), which in turn build up from allostratigraphischen consequences or lithostratigraphic formations.

  • Upper Bunter ( also referred to as Röt or Röt formation, see also Shuts sandstone)
  • Middle Bunter, with the Volpriehausen lineup, the Detfurth lineup, Hardegsen lineup and the Solling Formation ( see also Weser sandstone)
  • Lower red sandstone, with the Calvörde lineup and the Bernburg Formation

Economic Importance

The rocks of red sandstone, in particular from the layer of the Middle Buntsandstein, have been widely used because of their favorable properties ( eg, ease of cleavage ) as construction material for buildings (eg, churches, castles, bridges). The Freiburg and Strasbourg Cathedral, the Imperial Cathedral of Frankfurt / Main, Heidelberg Castle, the church of the monastery Alpirsbach, the Basler Munster, and the locust Castle in Aschaffenburg have been built under utilization of rocks of this lithostratigraphic group.

Former mining

In some layers of red sandstone copper ores are switched to a small extent. On Helgoland example, these very small chunks were gathered on the beach and smelted.

Natural Monuments

The sandstone forms in its distribution area often spectacular weathering forms: isolated rocks tens of meters in height. They are usually designated as natural monuments, such as the Devil's Table at Hinterweidenthal. In the Palatinate are found near Eppenbrunn called Altschlossfelsen. The massif has a length of 1.5 km and a height of up to 25 m probably the largest sandstone massif in the Palatinate. The 47 -meter-high " Lange Anna ", the most famous landmark of the island of Helgoland, in 1969 designated a natural monument.

Sources

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