White Jura

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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 upper of the three lithostratigraphic groups of the southern German Jura is referred to as the Weißer Jura (or Weißjura ) . In this context, South German Jura is not understood as a geographical term, but rather as a lithostratigraphic term in the sense of a lithostratigraphic supergroup . In the older and popular scientific literature, this term is equated with the chronostratigraphic series of the Upper Jurassic . This is not entirely correct, as the limits of the White Jura do not exactly coincide with the limits of the chronostratigraphically defined Upper Jurassic series. The term Malm , which is often used synonymously with the White Jura and Upper Jura, should also no longer be used in the southern German Jura. The term Malm is expected to be reserved for the roughly equivalent lithostratigraphic unit in the North German Jura. The southern German White Jura was deposited between 161 and 150 million years ago. The White Jura follows the lithostratigraphic group of the Brown Jura , the upper limit is erosive. Locally, the White Jura is overlaid with a large gap in the layers of the “Regensburg green sandstone” ( cenomanium ).

    history

    The term Weißer Jura was introduced by Leopold von Buch in 1837 in a lecture to the Royal Academy of Sciences in Berlin without any further definition. Friedrich August Quenstedt in his work "Das Flözgebirge Würtembergs", published in 1843, took up this term and defined it for the first time. The name was given because of the predominantly white rock colors of the rocks of the White Jura. In the past, the terms Malm and Upper Jura were often used as synonyms for the White Jura. Today, the term Upper Jurassic describes a chronostratigraphic series of the Jurassic . The term Malm or North German Malm will likely be reserved for a lithostratigraphic rock unit in the North German Jura. In the Quenstedt structure of the South German Jura, the White Jura is subdivided into six sections, which are designated with α , β , γ , δ , ε and ζ , for example White Jura α or White Jura α. The combination with Malm is even more common, for example Malm α.

    definition

    The lower limit of the White Jura is the base of the first light limestones of the Impressamergel Formation . The upper limit of the White Jura is erosive in the area of ​​the southern German Jura, which means that the respective upper limit is very different. The White Jura consists mainly of light limestone, limestone marl and marl. The maximum thickness is about 600 meters.

    Biostratigraphically, the lower limit of the lithostratigraphic unit of the White Jura can probably already be dated to the higher lower oxfordium , locally even to the middle Oxfordian of the Upper Jurassic, which means that the lower limits of the White Jura and Upper Jurassic do not exactly match. In the most complete profiles, the upper limit of the White Jura lies roughly in the border area between Lower and Upper tithonium . Here, too, the upper limit of the White Jura is significantly lower than the Jura-Chalk limit.

    Breakdown

    Lower rock limestone formation, quarry near Aalen

    The lithostratigraphic unit of the White Jura is currently divided into more than 20 formations, which, however, do not all lie on top of each other, but also represent each other laterally. The formations in their sequence from bottom to top, regional interlocking are side by side.

    Fossil sites

    In the upper part of the White Jura are the famous fossil deposits of Nusplingen , Eichstätt and Solnhofen ( Solnhofen formation ).

    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
    • Eckhard Mönnig: The Jura of Northern Germany in the Stratigraphic Table of Germany 2002. Newsletters on Stratigraphy, 41 (1-3): 253-261, Stuttgart 2005
    • Friedrich August Quenstedt: The Flözgebirge Würtembergs. With special consideration for the Jura . Laupp'sche Buchhandlung publishing house, Tübingen 1843.
    • Friedrich August Quenstedt: The Jura. Verlag der Laupp'schen Buchhandlung, Tübingen 1856–57.

    Web links

    Commons : Weißer Jura  - Collection of images, videos and audio files