Stuttgart formation

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Lithostratigraphy by the Keuper group in the Germanic Basin
Reed sandstone in formation as sandy-clayey "still water facies", detail of an outcrop near Gaildorf
Reed sandstone in "flood facies", abandoned quarry near Markertshofen

The Stuttgart Formation (formerly reed sandstone or reed sandstone layers ) is a sedimentary rock unit of the rank of a formation in the Keuper of the Germanic Triassic . The Stuttgart Formation is underlain by the Grabfeld Formation and the Benk Formation and overlaid by the Weser and Steigerwald Formations . The deposits of the Stuttgart Formation are predominantly of fluvial and lacustrine origin.

history

The name reed sandstone comes from the imprints of fossil horsetails in the rock, which used to be mistakenly interpreted as reeds . It goes back to Oscar Fraas , who introduced it to literature in 1845. The name Stuttgart Formation was proposed by Manfred Gwinner (1980) and officially accepted by the Perm-Triassic sub-commission of the German Stratigraphic Commission in 1997.

definition

The lower limit of the Stuttgart Formation in Northern Germany is the discordant area D2 of the Keuper. The upper limit is fuzzy and is defined by the end of the silty-sandy sedimentation and the onset of the plaster of paris. In southern Germany, the upper limit is drawn at the base of the main stone marl. Further north, the upper limit is placed at the base of the so-called Beaumont sulphate or the base of the Kühl's breccia. The Stuttgart formation is mainly characterized by sand and silt stones. Clay and limestone are also subordinate. The thickness reaches in northern Germany up to 100 m, on average about 40 to 60 m. In southern Germany the thickness varies from 40 m to 10 m. Laterally it is probably represented by the Ansbacher sandstone, the status of which has not yet been clarified or defined. The Stuttgart formation is dated to the middle Carnian ( Julium ). The STD 2002 estimates a deposition period of 1.5 million years (226 to 224.5 mya) for the Stuttgart Formation. There is a gap of 3 million years between the Stuttgart and Grabfeld Formations. The type locality of the Stuttgart formation is the state capital of Baden-Württemberg Stuttgart. The type region is Baden-Württemberg.

structure

In the middle of the Stuttgart formation there is a central bank that can be followed over greater distances, the “Gaildorfer Bank”. A subdivision into sub-information is (so far) not possible. In the Stuttgart formation, three small cycles can be distinguished.

Storage room

The sediments of the Stuttgart Formation were deposited in a wide, shallow basin, into which some river channels had cut into the underlying grave field formation, often several tens of meters deep. The valleys were then filled with sandstones in a second phase ("sandstone strands"). In a further cycle, valleys cut into the subsoil again and were again filled with sandstones. In a third cycle, the entire area was covered by sand and siltstones. Flood plains with root soils formed in the areas between the rivers. The Fennoskandische Schild ("Nordic Keuper") is considered to be the region of origin of the sands and silts .

Economical meaning

The reed sandstone, which is easy to work with, has been used in the past centuries to build houses, bridges, churches and monumental structures such as castles and palaces. Even today, reed sandstone is extracted in places and used as a building material for the renovation of historical buildings.

Fossils

The sandstones often contain larger remains of plants, especially horsetail ( Equisetites ). Fossil spores and pollen from land plants that are contained in the rocks give an even more extensive picture of the flora of that time and thus allow conclusions to be drawn about the climate in the central Carnian of Central Europe. Invertebrates are often ostracods (ostracods), clams and snails represented.

The terrestrial vertebrate fauna consists almost exclusively of temnospondyles . Some particularly well-preserved pieces have made the sites from which they come a certain fame. The remains of the stereospondyls Cyclotosaurus robustus and Metoposaurus diagnosticus were found in the quarries on the Feuerbacher Heide (today within Stuttgart) in the middle of the 19th century . From the quarry at the hunting lodge near Heilbronn skull parts date of Trematosauriers Hyperokynodon keuperinus . These two to four meters long "primeval corpses" lived in rivers and river deltas. In Mittelhausen, Thuringia, near Erfurt, bones from Metoposaurus and Cyclotosaurus as well as from gerrothorax were found.

Amniote discoveries, however, are very rare: So far we know only the skeleton of the enigmatic early crocodile relatives Dyoplax arenaceus from Stuttgart, one also originating from Stuttgart, under the name Zanclodon arenaceus described lower jaw fragment, the one Phytosaurier or one the Phytosauriern related crocodile relatives as well as the lower jaw fragment of a probably kannemeyeriiform dicynodontier from Obernzenn in Middle Franconia.

Individual evidence

  1. ↑ Stratigraphic table of Germany 2002 (see literature list )
  2. ↑ Martin Schmidt: The living world of our triad. Hohenlohe'sche Buchhandlung Ferdinand Rau, Öhringen 1928, 461 pp.
  3. ^ Andrew R. Milner: Late Triassic and Jurassic amphibians: fossil record and phylogeny. In: Nicholas C. Fraser, Hans-Dieter Sues (Ed.): In the Shadow of the Dinosaurs: Early Mesozoic Tetrapods. Cambridge University Press, Cambridge, UK 1994, ISBN 0-521-45242-2 , pp. 5-22.
  4. ↑ Tomasz Sulej: Species discrimination of the Late Triassic temnospondyl amphibian Metoposaurus diagnosticus. In: Acta Palaeontologica Polonica. Vol. 47, No. 3, 2002, pp. 535-546 (online)
  5. ↑ originally described as Capitosaurus robustus and Metopias diagnosticus , cf. Hermann von Meyer, Theodor Plieninger: Contributions to the paleontology of Württemberg, containing the fossil vertebrate remains from the Triassic formations with special consideration for the Keuper's labyrinthodonts. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart 1844, urn : nbn: de: bvb: 12-bsb10226184-7
  6. ^ Rainer R. Schoch, Andrew R. Milner, Hanna Hellrung: The last trematosaurid amphibian Hyperokynodon keuperinus revisited. In: Stuttgart contributions to natural history. Series B (geology and paleontology). No. 321, 2002 ( PDF 119 kB)
  7. ^ Spencer G. Lucas, Rupert Wild, Adrian P. Hunt: Dyoplax O. Fraas, a Triassic sphenosuchian from Germany. In: Stuttgart contributions to natural history. Series B (geology and paleontology). No. 263, 1998 ( BHL )
  8. ^ Michael W. Maisch, Andreas T. Matzke, Thomas Rathgeber: Re-evaluation of the enigmatic archosaur Dyoplax arenaceus O. Fraas, 1867 from the Schilfsandstein (Stuttgart Formation, lower Carnian, Upper Triassic) of Stuttgart, Germany. In: New Yearbook for Geology and Paleontology. Treatises. Vol. 267, No. 3, 2012, pp. 353-362, doi : 10.1127 / 0077-7749 / 2013/0317
  9. ↑ Axel Hungerbühler: The status and phylogenetic relationships of “Zanclodon” arenaceus : the earliest known phytosaur? In: Paleontological Journal. Vol. 75, 2001, pp. 97-112, doi : 10.1007 / BF03022600 .
  10. ^ Rainer R. Schoch: A dicynodont mandible from the Triassic of Germany forms the first evidence of large herbivores in the Central European Carnian. In: New Yearbook for Geology and Paleontology. Treatises. Vol. 263, No. 2, 2012, pp. 119-123, doi : 10.1127 / 0077-7749 / 2012/0216

literature

  • Gerhard Beutler: Lithostratigraphy. In: German Stratigraphic Commission (Ed.): Stratigraphie von Deutschland IV - Keuper. (= Courier Research Institute Senckenberg. Vol. 253). Schweizerbart Science Publishers, Stuttgart 2005, ISBN 3-510-61376-7 , pp. 65-84.
  • Gerhard Beutler, Norbert Hauschke, Edgar Nitsch: Facies development of the Keuper in the Germanic basin. In: Norbert Hauschke, Volker Wilde (Ed.): Trias - A whole other world. Central Europe in the early Middle Ages. Publishing house Dr. Friedrich Pfeil, Munich 1999, ISBN 3-931516-55-5 , pp. 129-174.
  • Edgar Nitsch: The Keuper in the Stratigraphic Table of Germany 2002: Formations and consequences. In: Newsletters on Stratigraphy. 41 (1-3), pp. 159-171, Stuttgart 2005, doi : 10.1127 / 0078-0421 / 2005 / 0041-0159 .
  • German Stratigraphic Commission (Ed. Coordination and Design: M. Menning and A. Hendrich): Stratigraphic Table of Germany 2002 (STD 2002) . Potsdam 2002, ISBN 3-00-010197-7 ( online )

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