Gryphae sandstone 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

    • The Gryphaeensandstein-Formation is a lithostratigraphic formation of the southern German Jura . It is used by the Bayreuth , Bamberg and z. Partly also underlaid discordantly by the Angulate sandstone formation and overlaid in a discordant manner by the Numismalis marl formation . In northeast Württemberg it interlocks to the west with the Arietenkalk Formation and the Obtususton Formation . To the east it wedges onto the Vindelician country . It reaches a thickness of up to 4 m and is dated to the Sinemurium .

    history

    The term Gryphaeensandstein-Formation was proposed by Gert Bloos, Gerd Dietl and Günter Schweigert in 2005 for the equivalents of the Arietenkalk- and Obtususton-Formation Jura in East Wuerttemberg and Northeast Bavaria, which were previously called "Gryphaeensandstein".

    definition

    The Gryphaeensandstein-Formation consists of marine, mostly quite coarse-grained sand-lime stones and coarse-sand marls. Thin, fine-grained sandstones with layers of flakes at the base of the formation still indicate intertidal conditions. Belemnites and ammonites in the upper part of the formation occupy a fully marine deposit area. The lower limit is defined by the onset of the coarse-grained, marine sand-lime brick. the upper limit in the west is the Cymbia Bank, the lowest bank of the Numismalis marl formation, in the east this bank is also called the "Blue Bank". In Franconia , a somewhat harder sand-lime stone bank is often formed at the top of the formation, the so-called aplanatum bank. The Gryphaeensandstein formation reaches a maximum thickness of 4 m.

    Temporal scope and distribution area

    The Gryphaeensandstein Formation can be dated to the Sinemurian, but it contains significant layer gaps, i.e. H. only parts of the Sinemurium are also documented by deposits. It extends from East Württemberg to northern Bavaria (Franconia and Upper Palatinate).

    Fossil guide

    The formation is relatively rich in fossils. In addition to species of the eponymous mussel genus Gryphaea, it also contains belemnites and ammonites . In the Aplanatum Bank, Gernot Arp found 18 species of mussels.

    Individual evidence

    1. ↑ Arp, 2007 - see profile (PDF; 907 kB)

    literature

    • Gert Bloos, Gerd Dietl, Günter Schweigert: The Jura of Southern Germany in the Stratigraphic Table of Germany 2002. In: Newsletters on Stratigraphy. Vol. 41, No. 1/3, 2005, ISSN  0078-0421 , pp. 263-277.

    Web links