Lower Keuper

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Germanic Triassic
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Myophoria goldfussi in the border dolomite
Fragment with about 4 mm large Palaeestheria minuta from the layers of estheria

The lower keuper (including sub keuper, Lettenkeuper, Lettenkohle, Letts carbon keuper) is a lithostratigraphic subgroup of Keupers of Germanic Trias . The lithostratigraphic unit is underlain by the Upper Muschelkalk subgroup and overlaid by the Middle Keuper subgroup. The deposits of the Lower Keuper indicate lacustrine conditions with occasional marine influences.


The lower limit of the Lower Keuper or the Erfurt Formation is the base of the Lettenkohlensandstein in the North German Basin. In southern Germany the lower limit is at the base of the Grenzbonebed. The upper limit is the border dolomite in the entire area .

The rocks are fluvial sandstones, claystones and thin coal seams, limestones and dolomites as well as evaporites in the form of sulphate tubers. The thickness averages about 60 to 80 m, in trench zones more than 100 m are reached. In southern Germany, the thickness varies from 30 m to 0 m at the basin edges towards the Vindelizisches Land . Biostratigraphically, the Lower Keuper is dated to the Ladinian ( Langobardian ) of the Middle Triassic . The type region is the Thuringian Basin. The type profile of the Erfurt formation is also the type profile of the Lower Keuper.


The Lower Keuper comprises only one formation in the North German Basin, the Erfurt Formation . In the southern German basin, the Erfurt formation is represented in the peripheral areas by the Grafenwoehr formation . This formation also includes the marginal facies of the shell limestone . The establishment of further formations in the western edge areas ("edge area to the Ardennes threshold" and "edge facies in the Baltic Sea area") is necessary, but has not yet taken place.

The Lower Keuper can also be divided into nine small cycles.

Storage room

The rocks of the Lower Keuper were deposited in a wide and shallow basin with river channels, lakes and swamps, which the sea occasionally penetrated through the Burgundian Gate. These short-term, cyclical sea advances are documented by marine fauna as far as southern Lower Lusatia and the Osnabrück mountainous region. The rivers came from the Fennoscand Shield. In the land areas between the rivers and lakes, clays were deposited, which show evidence of brief flooding and drying out (sulphate bulbs). Root soils are common.


The Lower Keuper is z. T. extremely rich in fossils . Often, mussels (Bivalvia), ostracods (Ostracoda), Shell Schaler (Conchostraca), brachiopods (brachiopods), as a great rarity, there are also cephalopods (Cephalopoda). In the border bonebed , the bones and teeth of vertebrates (fish, amphibians and other terrestrial vertebrates ) are enriched. In Kupferzell 1977 numerous in the upper part of the Lower Keuper amphibians were discovered as Mastodonsaurus , gerrothorax , Plagiosuchus and Kupferzellia . Teeth of therapsids ("early mammalian relatives"), rauisuchi and nothosaurs were also found. Plant remains ( Equisetites and Neocalamites ) occur in the coals and coal layers ; these layers also contain a rich microflora ( spores and pollen ).


  • Gerhard Beutler: Lithostratigraphy. In: German Stratigraphic Commission (Ed.): Stratigraphie von Deutschland IV - Keuper. Courier Forschungsinstitut Senckenberg, 253: 65-84, Stuttgart 2005 ISSN  0341-4116
  • Klaus-Peter Kelber: The sunken flora from the delta swamps of Main Franconia 230 million years ago. Macro flora from the Germanic Unterkeuper. Beringeria, special issue 1, 67 pp., 100 ill .; Wuerzburg 1990.
  • Edgar Nitsch: The Keuper in the Stratigraphic Table of Germany 2002: Formations and consequences. Newsletters on Stratigraphy, 41 (1-3): 159-171, Stuttgart 2005 ISSN  0078-0421

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