Bayreuth 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 Bayreuth Formation is a lithostratigraphic formation of the southern German Jura . It is underlain discordantly by the Keuper , often with large gaps in the layers, and also mostly overlaid discordantly by the Gryphaeensandstein Formation . In northern Bavaria it interlocks to the west with the Bamberg formation , further to the east it wedges out onto the Vindelizische Land . It reaches a thickness of up to about 10 m and is dated into the hettangium .

    history

    The term Bayreuth Formation was proposed by Gert Bloos, Gerd Dietl and Günter Schweigert in 2005 for the predominantly terrestrial equivalents of the lower Jura in northeastern Bavaria, previously referred to as Gümbelscher sandstone .

    definition

    The Bayreuth formation consists of terrestrial, fluvial , more rarely lagoon and brackish sandstones. They were deposited in fluvial gullies, these gullies often cutting deep into the Keuper below. Two advances of these gullies to the west have been documented, at the base of the Jura and at the Hettangian / Sinemurian border . The respective deposits were partially eroded again by the subsequent sea advances. The deposits of the Bayreuth Formation are therefore often only preserved in the former river channels. The thickness reaches up to about 10 m. The lower limit is the onset of the sandstones above the erosive base of the Jura, the upper limit forms the base of the Gryphaeensandstein formation , which begins with a layer gap above the Bayreuth formation.

    Temporal scope and distribution area

    The dating of the fluvial and terrestrial deposits of the Bayreuth Formation or the correlation with the international chronostratigraphic levels is difficult. It can only be dated in the Hettangian by its relative position above the Keuper deposits and the Gryphaeensandstone formation above . The formation is restricted to northeast Bavaria. It extends on the east side of the Franconian Alb from Hochstadt m Main to south of Bayreuth; on the west side of the Franconian Alb it extends from Forchheim in the north to Neumarkt in the Upper Palatinate in the south. In the west it interlocks with the Bamberg formation. Individual deeply cut channels in the Bayreuth Formation occur as far as Bamberg and prove that the formation was originally spread further west.

    Fossil guide

    The famous Lias- Flores of Franconia were found in clay lenses of the Bayreuth Formation near Bayreuth and Schnaittach . Further points of discovery for these Lias floras are in Sassendorf and Strullendorf near Bamberg.

    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

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