Bamberg 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 Bamberg Formation is a lithostratigraphic formation of the southern German Jura . It is underlain by the Exter Formation of the Upper Keuper and overlaid by the Gryphaeensandstein Formation . In Baden-Württemberg, it meshes with the Angulate Sandstone and Psilonotenton Formations . Further to the east or northeast, it is laterally represented by the Bayreuth formation . It reaches an average thickness of 8 to 20 m, locally also up to 42 m and is dated in the Hettangian to Untersinemurium .

    history

    The term Bamberg Formation was proposed by Gert Bloos, Gerd Dietl and Günter Schweigert in 2005 for the equivalents in northern Bavaria, previously known as Angulate sandstone and Psilonotenton. Since the proportion of sandstones is lower here and the separating oolite bank (to the Psilonotenton Formation) is mostly missing, Angulate Sandstone and Psilonotenton were combined into a new lithostratigraphic unit, the Bamberg Formation.

    definition

    The Bamberg formation consists of claystones with embedded, flat fine sand and siltstone banks . The thickness varies in northern Bavaria between 8 and 20 m, in Lower Franconia on the Großer Hassberg up to 45 m. The lower limit is the bottom bank, the equivalent of the Psilonotenbank of the Psilonotenton Formation. In Franconia, however, it is a thin, fossil-bearing sandstone. Type region is the area around Bamberg.

    Temporal scope and distribution area

    The bottom bank represents the transgression of the marine Jura in Northern Bavaria, which begins in the Unterhettangium. The lowest time intervals of the Jura are missing, however. The upper limit is strongly diachronic. In Oberfranken Bamberg the formation is to the Hettangian limited in Unterfranken (Large Hassberg) it extends at a significantly higher thickness up to the Untersinemurium inside. The formation is limited to northern Bavaria; a possible expansion to eastern Württemberg has not yet been decided. The dividing border bank between the Angulate Sandstone Formation and the Psilonotenton Formation is also missing and both formations could be lithologically combined. To the west, it interlocks with the Psilonotenton Formation and the Angulate Sandstone Formation . Further to the east of the Jura Basin in northeast Bavaria, the Bamberg Formation merges into the terrestrial and fluvial, and more rarely lagoon-brackish facies of the Bayreuth Formation.

    Breakdown

    The Bamberg formation is subdivided into the Forchheim subformation. It stretches in the north from Hochstadt am Main to the south in the Ries . It is a coastal facies with fine-grained, massive sandstones that are very low in fossils.

    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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