Medium red sandstone

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Germanic Triassic
-250 -
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-245 -
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-240 -
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-235 -
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-230 -
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-225 -
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-220 -
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-215 -
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-210 -
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-205 -
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-200 -


The middle red sandstone is a lithostratigraphic subgroup of the red sandstone group of the Germanic Triassic . The lithostratigraphic unit is underlain by the Bernburg formation of the Lower Buntsandstein and overlaid by the sub-group of the Upper Buntsandstein (synonymous with the Röt formation ).

definition

The lower limit of the Middle Buntsandstein is defined by the base of the Volpriehausen formation. This limit coincides with a discordance and a pronounced change or increase in the grain size. The upper limit forms the basis of the red formation . The lower limit of the Middle Buntsandstein is biostratigraphically in the Lower Olenekian , the upper limit is in the lowest anisium . In geochronology, this correlates with the period from 249 to 244.5 million years.

structure

The middle red sandstone is divided into four lithostratigraphic formations or four allostratigraphic sequences, which in this case are identical. In red sandstone, the terms formation or sequence are often used synonymously. The four formations / sequences from top to bottom:

Storage room

The deposit area of ​​the Middle Buntsandstein was a shallow basin into which rivers penetrated from the northern high areas to the basin interior. The sedimentation is caused by z. T. mighty fluvial sandstones and conglomerates shaped. Also aeolian , lacustrine, lacustrine and lagoonal deposits occur. Soil horizons that can contain lime crusts are particularly widespread in the peripheral areas. At the border to the Upper Buntsandstein, a carnelian - dolomite horizon is formed, especially in the southern basin areas, which can also be interpreted as the soil horizon.

Lange Anna , middle red sandstone from Heligoland

Fossils

Due to the semi-arid to arid climate, only very low-species fauna can usually be found in the middle red sandstone. Among the vertebrates, there are some small reptiles (including Procolophonians ), " Labyrinthodontier " such as Trematosaurus (a relatively large Temnospondyle ) and trace fossils such as Chirotherium (footsteps and tracks of earlier archosaurs ). The invertebrates include conchostracs , mussels and ostracods . Among the plant fossils are Pleuromaia ( bear moss family ), Schizoneura ( fern ) and Voltzia ( conifer ). Spores and pollen are relatively common, including those of the bear moss family.

Individual evidence

  1. According to the latest dating from Menning et al. (2005) this period should be corrected to between 250.6 and 247.4 million years. However, the authors recommend using the numbers in the Stratigraphic Table of Germany until the new dates can be further confirmed.

literature

  • Manfred Menning, Reinhard Gast, Hans Hagdorn, Karl-Christian Käding, Theo Simon, Michael Szurlies and Edgar Nitsch: time scale for Permian and Triassic in the Stratigraphic Table of Germany 2002, cyclostratigraphic calibration of the higher Dyas and Germanic Triassic and the age of the Roadium stages to Rhaetium 2005. Newsletters on Stratigraphy, 41 (1-3): 173-210, Stuttgart 2005 ISSN  0078-0421
  • Jochen Lepper, Dietrich Rambow and Heinz-Gerd Röhling: The red sandstone in the Stratigraphic Table of Germany 2002. Newsletters on Stratigraphy, 41 (1-3): 129-142, Stuttgart 2005 ISSN  0078-0421

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