Lower Muschelkalk
The Lower Muschelkalk is a lithostratigraphic subgroup of the Muschelkalk of the Germanic Triassic . The lithostratigraphic unit is underlain by the red formation of the Upper Buntsandstein and overlaid by the subgroup of the Middle Muschelkalk . After the mostly continental deposits of the Buntsandstein, large parts of the Germanic Basin in the Lower Muschelkalk were flooded by a shallow sea. The deposits of the lower shell limestone (or only parts of it) are also referred to as "wave limestone" in older and / or popular scientific literature.
definition
The lower limit of the Lower Muschelkalk is defined by the base of the so-called border yellow limestone. The upper limit forms the base of the middle shell limestone , which is usually drawn with the so-called "orbicularis layers". The lower limit of the Lower Muschelkalk is biostratigraphically in the lower anisium , the upper limit is in the middle anisium. In geochronology this correlates with the period from 243 to 240 million years.
structure
The Lower Muschelkalk is divided into five lithostratigraphic formations. However, the five formations are usually not on top of each other, but represent each other regionally:
- Jena formation , it is formed in the central part of the pelvis and represents the entire lower shell limestone there
- Freudenstadt formation , in the southern edge area (Black Forest)
- Udelfangen formation , also known as “shell sandstone”, in the western edge of the basin in the Eifel and Saar areas
- Eschenbach formation , also known as “shell sandstone”, in the eastern edge of the basin in the Upper Palatinate
- Rüdersdorf formation , in the higher part of the Lower Muschelkalk in Brandenburg
Storage room
The depository of the Lower Muschelkalk was a shallow sea basin that was only fully marine in the northern, central and eastern basin areas . In the basin areas there was the formation of ooids and carbonate sands. In the southern edge area ( Freudenstadt Formation ), limes and clay marls near the coast were deposited. T. are dolomitic. On the western and eastern edges mostly fine-grain sandstones, clay and marl stones were deposited ("shell sandstone"). The deposits contain fully marine fauna. Only the upper area of the Udelfangen formation on the western edge of the basin is no longer fully marine.
Individual evidence
- ↑ According to the latest dating by Menning et al. a. (2005) this period should be corrected to between 246.6 and 244.6 million years and thus to a period of 2 million. 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, Edgar Nitsch: Time scale for Permian and Triassic in the Stratigraphic Table of Germany 2002, cyclostratigraphic calibration of the higher Dyas and Germanic Trias and the age of the Roadium stages to Rhaetium 2005. In: Newsletters on Stratigraphy. 41 (1-3), pp. 173-210, Stuttgart 2005 ISSN 0078-0421
- Hans Hagdorn, Theo Simon: Der Muschelkalk in the Stratigraphic Table of Germany 2002. In: Newsletters on Stratigraphy. 41 (1-3), pp. 129-142, Stuttgart 2005 ISSN 0078-0421
- Norbert Hauschke, Volker Wilde (Hrsg.): Trias A whole different world of Central Europe in the early Middle Ages. Publishing house Dr. Friedrich Pfeil, Munich 1999, ISBN 3-931516-55-5 .