Wedelsandstone 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 Wedelsandstein Formation is a lithostratigraphic formation of the southern German Jura. From east to west it is covered by the Eisensandstein , Eichberg or Murchisonaeoolith Formation and the Ostreenkalk Formation . It reaches a thickness between 25 and 40 m and is dated to the lower bajocium .

    history

    The term Wedelsandstein was already used by FA Quenstedt in 1843 and equated with its stratigraphic unit Braunjura gamma. A type locality as it is required for the definition of a lithostratigraphic unit has not yet been determined.

    definition

    The sandstone formation is characterized by dark gray, brownish, z. Partly also characterized yellowish, sandy clays and marls, in which sand-lime stone banks and sandstone banks can intervene. The thickness varies in the area of ​​the Swabian Alb between 25 and 40 m. The lower limit is defined by the lower edge of the so-called Sowerbyi oolite. The upper limit forms the basis of the so-called giganteus tone. The key abbreviation of the State Office for Geology, Raw Materials and Mining Baden-Württemberg for the Wedelsandstone Formation in geological maps is bj1.

    Temporal scope and distribution area

    The sediments of the frond sandstone formation were deposited during the Lower Bajocian. The frond sandstone formation includes the ammonite zones of the Hyperlioceras discites , the Fissilobiceras ovale , the Witchellia laeviuscula and the Sonninia propinquans (regionally roughly corresponds to the Emileia sauzei zone). The formation is widespread on the Swabian Alb and in its foreland, in the Molasse basin , in the Kraichgau and in the Upper Rhine Graben.

    Breakdown

    The sandstone formation contains the so-called Sowerbyi oolite (approx. 1.5 m) at the base, which got its name from the earlier sowerbyi - ammonite zone . The sowerbyi biozone (named after the ammonite Stephanoceras sowerbyi or Sonninia sowerbyi ) has now been replaced by the internationally used laeviuscula ammonite zone (named after the ammonite Witchellia laeviuscula ). The actual Wedelsandstones (= Wedelsandstone subformation) make up by far the largest share. The so-called blue lime is formed at the top of the episode .

    Fossil guide

    In the frond sandstone formation, macrofossils mainly contain ammonites and mussels . Reef corals also occur regionally (e.g. near Hechingen ).

    literature

    • Friedrich August Quenstedt: The Flözgebirge Wuerttemberg. Laupp Publishing House, Tübingen 1843.
    • Friedrich August Quenstedt: The Jura. Laupp Publishing House, Tübingen 1856–57.
    • 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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