Arietenkalk formation
The Arietenkalk Formation is a lithostratigraphic formation of the southern German Jura. It is underlain by the Angulate Clay Formation and the Angulate Sandstone Formation and overlaid by the Obtus Clay Formation . In Franconia , it meshes with the Gryphae sandstone formation . It is dated to the Sinemurium .
history
The term Arietenkalk appears as early as 1843 in Friedrich August Quenstedt's work Das Flözgebirge Würtembergs . He already understood the term as lithostratigraphic.
definition
The Arietenkalk formation consists of gray limestone and marl, in which regional bituminous layers can also be incorporated. In the lower part, the limestone banks also contain chamositoids and regional fine sands. The thickness in Württemberg is between 2 and 22 m, in the central Upper Rhine area up to 25 m. In the southern Upper Rhine area, however, only 3 m are reached. The lower limit of the Arietenkalk Formation is marked by a (usually not very sharp) alternation between the clayey-sandy rocks of the Angulate Clay Formation and the Angulate Sandstone Formation . In Württemberg, the so-called "copper rock bank" is formed at the base of the Arietenkalk formation. The upper limit is the clay package of the Obtususton formation , at the base of which there is a rich layer, the so-called Capricornenlager, i.e. the base of the Capricornenlager forms the upper limit of the Arietenkalk Formation. Chronostratigraphically , the Arietenkalk Formation essentially comprises the Lower Sinemurium , but still extends slightly into the Upper Sinemurium.
Breakdown
The Arietenkalk formation is formally not further subdivided. In the base, the so-called copper rock bank is regionally eliminated, but it is not developed everywhere. Also, this term is obviously used to refer to different banks.
Fossil guide
The Arietenkalk Formation is known for the spectacular finds of ammonites of the genus Arietites (and closely related genera) up to over meters in size .
literature
- Gert Bloos, Gerd Dietl & Günter Schweigert: The Jura of Southern Germany in the Stratigraphic Table of Germany 2002. Newsletter on Stratigraphy, 41 (1-3): 263-277, Stuttgart 2005 ISSN 0078-0421
- Friedrich August Quenstedt: The Flözgebirge Würtembergs. With special consideration for the Jura . Laupp'sche Buchhandlung publishing house, Tübingen 1843.
- Friedrich August Quenstedt: The Jura. Verlag der Laupp'schen Buchhandlung, Tübingen 1856–57.
Web links
- German Stratigraphic Commission (Ed.): Stratigraphische Tisch von Deutschland 2002 . Potsdam 2002, ISBN 3-00-010197-7 , PDF; 6.57 MB (large)
- Lower Jurassic in Baden-Württemberg ( Memento from September 15, 2011 in the Internet Archive ) (PDF; 12 kB)