Jurensis marl 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
    • " Hammerstadt ammonite soap"

    The Jurensis marl formation is a lithostratigraphic formation of the southern German Jura . It is covered by the Posidonia schist formation and the Opalinus Clay formation . It reaches a thickness of over 30 m and is dated in the oberto arcium .

    history

    The term Jurensis marl was used by FA Quenstedt in 1843. He equated it with his stratigraphic unit Lias zeta. Since 2002 this lithological unit is also known as the Jurensis marl formation. A type locality as it is required for the definition of a lithostratigraphic unit has not yet been determined.

    definition

    The Jurensis marl formation is characterized by gray, brownish, and sometimes yellowish marl and marl limestones in which tuberous limestone and condensation horizons ("ammonite soaps") can intervene. The thickness varies greatly in the Swabian Alb area from 0.6 m to 13 m. In the Middle Upper Rhine region, a thickness of over 30 m can be achieved. The lower limit is defined by a processing horizon; the boundary to the Posidonia schist formation is almost always erosive, that is, a layer gap is formed between the two formations. The key abbreviation of the State Office for Geology, Raw Materials and Mining (Baden-Württemberg) for the Jurensis marl formation in geological maps is tc2.

    Temporal scope and distribution area

    The sediments of the Jurensis marl formation were deposited during the Oberto Arcian . The Jurensis marl formation includes at most the ammonite zones of Haugia variabilis , Grammoceras thouarsense , Dumortieria levesquei and Pleydellia aalensis . The formation is common in the Swabian Alb, in the foothills of the Alb, in the Molasse basin , in the Kraichgau and in the Upper Rhine Graben. On the Franconian Alb it is replaced by thin dark clays and clay marl.

    Breakdown

    Just below the middle of the thickness, the Jurensis marl formation contains the so-called "ammonite soaps", horizons with concentrations of ammonite shells. They are called “Hammerstadter Breccia” by Aalen or “Boller Breccia” by Boll .

    literature

    • Friedrich August Quenstedt: The Flözgebirge Wuerttemberg. Laupp Publishing House, Tübingen 1843.
    • Friedrich August Quenstedt: The Jura. Laupp Publishing House, Tübingen 1856–1857.
    • Gert Bloos, Gerd Dietl, Günter Schweigert: The Jura of Southern Germany in the Stratigraphic Table of Germany 2002. In: Newsletter on Stratigraphy. 41 (1-3), 2005, pp. 263-277, ISSN  0078-0421 .
    • Eckhard Mönnig: The Jura of Northern Germany in the Stratigraphic Table of Germany 2002. In: Newsletters on Stratigraphy. 41 (1-3), 2005, pp. 253-261, ISSN  0078-0421 .

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