Saxonium
The Saxonium , also shortened to Saxon (or in the French form Saxonien used), is in the Earth's history , a no longer used today regional or supra-regional level of Perm . It was often used synonymously with Oberrotliegend . The Rotliegend is a term used in lithostratigraphy and equating it with a (supposedly) chronostratigraphic unit is therefore extremely problematic. There are also major problems with defining the boundaries for various reasons. It is recommended that the term no longer be used in publications today. However, it is of great historical interest as it is widely used in older literature. The term Saxonium should not be confused with the geotectonic term Saxonikum .
History and naming
The saxonium was proposed by French geologists Ernest Munier-Chalmas and Albert de Lapparent in 1893. They wanted to use it to designate red sandstones under the Zechstein, which are open near Mansfeld in the southern Harz foreland. The area was then generally referred to as Saxony, but is now in the state of Saxony-Anhalt.
Definition and correlation
The basis of the Saxonium (= Oberrotliegend sensu auctorum) is extremely problematic. It was defined by Haubold & Katzung (1972) with the first appearance of the trace fossils Tambachichnium schmidti and Palmichnus tambachensis in the Tambach formation of the Thuringian Forest. This definition is completely inappropriate. The two trace fossils were only found in the Thuringian Forest and can therefore not be used to subdivide the Rotliegend into other Dyas basins. Tambachichnium schmidti was later found in older formations of the Rotliegend in the Thuringian Forest; also is Tambachichnium schmidti a synonym of varanops microdactylus . Trace fossils are also heavily dependent on tradition. Boy & Fichter (1988) suggested starting the Saxonium with the base of the Varanops microdactylus zone in unit N3 (= lower Nahe subgroup) in the Saar-Nahe basin. However, this level is well below the originally proposed limit in the Thuringian Forest.
The upper limit, and thus the limit to the thuringium, is also fraught with many inadequacies. The border of the thuringium originally coincided with the onset of the Zechstein. Later attempts were made to define the border with the help of microflora. In other regions, however, these obviously set in much earlier, so that the basis of the thuringium (and thus the upper limit of the saxonium) was correlated very differently. Some authors put the lower limit in the Kungurium or Artinskium . So far it has not been taken into account that the Oberrotliegend has practically no microflora due to the oxidation of organic material.
Because of the difficulty of defining boundaries for the saxonium, Menning et al. (2005) on the further use of the term.
swell
Individual evidence
- ↑ Spencer G. Lucas, Joerg W. Schneider and Giuseppe Cassinis: Non-marine Permian biostratigraphy and biochronology: an introduction. In: Spencer G. Lucas, Giuseppe Cassinis and Joerg W. Schneider (Eds.): Non-Marine Permian Biostratigraphy and Biochronology. Geological Society, London, Special Publications, 265, 1-14, London 2006 PDF
literature
- Manfred Menning, Reinhard Benek, Jürgen Boy, Bodo-Carlo Ehling, Frank Fischer, Birgit Gaitzsch, Reinhard Gast, Gotthard Kowalczyk, Harald Lützner, Wolfgang Reichel and Jörg W. Schneider: Das Rotliegend in the Stratigraphic Table of Germany 2002 - "Paternoster- Stratigraphy ”on the retreat. Newsletters on Stratigraphy, 41 (1-3): 91-122, Stuttgart 2005 ISSN 0078-0421