Posidonia slate formation

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Lithostratigraphy of the South German Jura .
Abbreviations:
  • Humph.-Fm. = Humphriesioolite Formation
  • L.Bk-Fm = Lying bench lime formation
  • H.Bk-Fm = hanging bank lime formation
  • Zm-Fm = cement marl formation
  • S.-Fm = Solnhofen formation
  • Rö.-Fm = Rögling formation
  • U.-Fm = Usseltal formation
  • Mö.-Fm = Mörnshein formation
  • N.-Fm = Neuburg formation
  • R.-Fm = Rennertshofen formation
    • Fossil imprint of the ammonite Harpoceras falciferum in the Posidonia schist of Holzmaden
    Posidonia schist at the beginning of the geological nature trail on the Hesselberg
    Belemnitenrostrum in marl at the base of the Posidonia slate

    The Posidonia schist formation is a lithostratigraphic formation of the southern German Jura . It is underlain by the Amaltheenton Formation , and overlaid by the Jurensis Marl Formation . A smaller layer gap is formed between the Posidonia schist formation and the Jurensis marl formation .

    definition

    The Posidonia slate formation is defined with the upper edge of the highest so-called “Costaten Bank”. The upper limit is defined by a work-up horizon that extends over a shift gap of different sizes. The Posidonia schist formation consists of marls and marl limestones at the base with bituminous layers. In the middle part, the bituminous, finely layered marls (the so-called " Posidonia schist ") dominate with a few bituminous limestones. In the upper part, the bituminous content decreases again. The thickness reached in the area around the famous Fossil reference of Holzmaden about 12 m to 14th In the middle Upper Rhine area up to 34 m can be reached. In contrast, it is only about 6 m in the southern Upper Rhine area. The Posidonia schist formation is locally eroded by incising grooves to different depths . Therefore, in francs z. B. a very different thickness from 2 to 15 m. The sediments of the Posidonia schist formation were deposited during the Subertoarcian and include the ammonite zones of the Dactylioceras tenuicostatum ( Tenuicostatum zone ), the Harpoceras falciferum ( Falciferum zone ) and the Hildoceras bifrons ( Bifrons zone ). Due to the local erosion of the upper part of the Posidonia schist formation, the Bifrons and even parts of the Falciferum zone may be missing.

    Breakdown

    The Posidonia schist formation is formally not further subdivided. However, the individual sections and more solid benches in the area of ​​Holzmaden have been given a multitude of names due to the long-term mining of Posidonia slate (e.g. Tafelfleins, Seegrassschiefer, Koblenzer, Steinplatte, Wilder Stein, Falchen and many more) that come from the stone processing industry.

    Fossil guide

    The Posidonia schist formation is world-famous for the excellently preserved fossils that were found mainly in the area of ​​Holzmaden. Numerous fossil finds from the Posidonia schist formation are exhibited in the Museum am Löwentor (part of the State Museum for Natural History Stuttgart ), in the paleontological collection of the University of Tübingen and in the Urwelt Museum Hauff .

    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 Jura. Verlag Laupp, Tübingen 1856–1857, online edition , as well as atlas on the Jura . Verlag Laupp, Tübingen 1858 ( online edition , supplement to the aforementioned volume).

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