Autunium
The Autunium , also shortened to Autun (or also used in the French form Autunia ), is a regional or supra-regional level of the Permian that is no longer used today in geological history . It was often used synonymously with Unterrotliegend . However, the Rotliegend is a term used in lithostratigraphy and equating it with a chronostratigraphic level is therefore extremely problematic. The duration of the Autunium varies considerably depending on the author, and there are also major problems in defining the limits for various reasons. Today the term should no longer be used in publications. However, it is of great historical interest as it is widely used in older literature.
History and naming
The Autunium is named after the town of Autun in the Saône-et-Loire department , France. The term goes back to Karl Mayer-Eymar , who eliminated the "couches d'Autun" for the first time in 1881 and introduced Autunin as the time term . The term in today's sense or today's spelling comes from Jules Bergeron , who coined it in his dissertation in 1889. In 1893 Albert de Lapparent first defined "les schistes bitumineux des environs d'Autun et les couches correspondantes". A first more precise definition was only given by Paul Bertrand in 1918, who defined the basis of the Autunium with the first appearance of "Callipteris" conferta (today Autunia conferta ). Haubold & Katzung (1972) understood the Autunium as a national series, Boy & Katzung (1988), on the other hand, as a (regional) level. Menning et al. (2005) advise against using the terms autunium, saxonium and thuringium in Germany.
Definition and correlation
The basis of the Autunium (and thus the Central European Permian) was defined by Paul Bertrand in 1918 with the first appearance of 'Callipteris' conferta (today Autunia conferta from the Peltaspermales group ). This definition of the beginning of the Autunium (and the Permian in Central Europe) is extremely problematic. Later it turned out that deposits with plant fossils regarded as Stefan alternate with deposits or are laterally represented that contain Autunian plant fossils. This is because Autunia was mesophilic or xerophilic and did not occur in moist locations. Autunia fossils are also less preserved than plants near water. These have better chances of preservation and transmission in water than Autunia on dry locations. The callipterids are also relatively difficult to determine; many determinations of Autunia conferta are incorrect determinations and must be corrected. According to current knowledge, Autunia conferta is already used in the Stefan B ( Stefanium B) by Blanzy , so it starts clearly in the higher carbon. In the Rotliegend of the Saar-Nahe Basin , however , Autunia conferta only begins well above the base of the Rotliegend. The beginning of Stefan B of the European Upper Carboniferous is now correlated with the highest part of the international chronostratigraphic Kasimovium stage; it extends into the lower Gzhelium level. There is thus a clear discrepancy between the biostratigraphically defined beginning of the Autunium and the beginning of the lithostratigraphically defined Unterrotliegend, with which the Autunium was previously correlated.
The upper limit or the limit to the following regional level of the Saxonium (= Oberrotliegend sensu auctorum) is similarly problematic. The basis of the Saxonium was defined by Haubold & Katzung (1972) with the first onset of Tambachichnium schmidti and Palmichnus tambachensis in the Tambach formation of the Thuringian Forest. This definition is just as unsuitable as the definition of the lower limit. The two trace fossils have so far only been found in the Thuringian Forest and therefore cannot 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.
Because of the difficulties in defining boundaries for the Autunium, Manfred Menning et al. (2005) on the further use of the term.
swell
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 decline. Newsletters on Stratigraphy, 41 (1-3): 91-122, Stuttgart 2005 ISSN 0078-0421
- 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