Stefanium

The Stefanium , often shortened to Stefan (also used in the French form Stéphanien ), is a period of the Carboniferous ( Paleozoic ) in geological history . It is the upper regional or supra-regional level of the carbon or the subsystem silesium . It is underlain by the regional level of the Westfalium and overlaid by the regional level of the Autunium , the lowest level of the Permian of Central Europe ( Dyas ). The term could not establish itself in international use and corresponds to the global chronostratigraphic levels of the Kasimovium and the lower Gzhelium . More recent studies have shown that the Stefanium / Autunium boundary runs diachronically or is facies-dependent and lies within the global carbonate. Expressed in absolute numbers, the Stefanian period begins at around 305 million years and ends regionally and facially differently at around 302 to around 300 million, i.e. well before the global Carbon / Permian boundary, which is geochronologically dated to 299 million years.

History and naming

The term Stefanium or Stéphanien was introduced into literature by Ernest Munier-Chalmas and Albert de Lapparent in 1894. It is named after the city of Saint-Étienne ( Loire department , France). The Latin name of the city is Stephanus .

Definition and correlation

Fossil of Annularia stellata

The base of the Stefanium was primarily defined lithologically and facially. Limnic -terrestrial layers containing plant fossils ( Bowmanites verticillata (Schlotheim) Hoskins & Crosse, 1943, Annularia stellata and Pecopteris polymorpha ) set in above a discordance with a probably clear layer gap . In the marine area, the foraminifera genus Triticites is used . The Westfalium / Stefanium limit is now correlated with the Moskovium / Kasimovium limit. The controversial Cantabrium lower level is counted as part of the Stefanium. However, it cannot be proven outside of northern Spain. Therefore the current Westphalian / Stefanium limit is still subject to certain uncertainties.

The upper limit of the Stefanium (and thus of the Central European Carboniferous) and the lower limit of the Autunium (and thus the limit of the Central European Permian) was determined by Bertrand (1918) with the first appearance of "Callipteris" conferta (today Autunia conferta from the group of Peltaspermales ) Are defined. 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 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 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 Stefanium B of the European Upper Carboniferous is today 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 absolute ages of Stefanium are correspondingly uncertain. According to the Stratigraphic Table of Germany 2002 (STD2002) it ranges from 305 to about 302/300 million years with a strongly diachronic upper limit. According to the calibrated timescale by Menning et al. (2006) from around 306 to 300 million years or from around 307 to 302 million years in the International Stratigraphic Chart 2009 , with the global Moskovian / Kasimovian boundary being calculated from the mid-Gzhelian.

Subdivision of the Stefanium

The regional level of the Stefanium has traditionally been divided into three sub-levels, which were designated as Stefanium A, B and C. Some authors tried to establish a Stefanium D, which turned out to be unsustainable. In Central Europe, the Stefanium lies discordantly on the Westfalium D with a shift gap of unknown duration. RH Wagner (1969) described the Cantabrium (also Cantabrium) at the base of the Stefanium from Cantabria , where the transition is more complete . The Stefanium A was later renamed the Barruelium . For the Stefanium B / C, Doubinger et al. (1995) introduced a new stage Forezium (Forezien) before, after Forez , a landscape in France that has so far received little attention.

Stefanium C (Forezium)
Stefanium B (Forezium)
Stefanium A ( Barruelium )
Cantabrium (also Cantabrium)

swell

Individual evidence

↑ ^a ^b according to the Stratigraphic Table of Germany. These ages differ slightly from the ages in the International Stratigraphic Chart from 2009
^ Hans Murawski, Wilhelm Meyer: Geological dictionary . 10th edition, Enke Verlag, Stuttgart 1998, ISBN 3-432-84100-0 .
↑ see Menning et al .: A numerical time scale for the Pennsylvania in Central Europe. Courier Research Institute Senckenberg, Frankfurt / M. 2005, ISBN 3-510-61380-5 , p. 191.
^ Barry C. Richards: Current Status of the International Carboniferous Time Scale. In SG Lucas et al. (editors) 2013: The Carboniferous-Permian Transition. New Mexico Museum of Natural History and Science Bulletin 60: 348-353. PDF
^ RH Wagner, CF Winkler Prins: The Cantabrian and Barruelian stratotypes: a summary of basin development and biostratigraphic information. In: Lemos de Sousa, MJ, Wagner, RH (Eds.): Papers on the Carboniferous of the Iberian Peninsula (Sedimentology, Stratigraphy, Paleontology, Tectonics and Geochemistry). Anais da Facultade de Ciencias, Supplement, 64 (Sp. Vol.), Universidade do Porto, 1985, pp. 359-410 online
↑ J. Doubinger, P. Vetter, J. Langiaux, J. Galtiert, J. Broutin: La flore fossile du bassin houiller de Saint-Étienne. Mémoires du Muséum National d'Histoire Naturelle, Paris 1995, ISBN 2-85653-218-7 , pp. 1-355 Abstract .

literature

Manfred Menning, Dieter Weyer, Immo Wendt, Günther Drozdzewski: A numerical time scale for the Pennsylvania in Central Europe. Courier Research Institute Senckenberg, Frankfurt / M. 2005, ISBN 3-510-61380-5 , pp. 181-198

Web links

[STD2002-1] rding to the Stratigraphic Table of Germany. These ages differ slightly from the ages in the International Stratigraphic Chart from 2009

[Murawski-2] Hans Murawski, Wilhelm Meyer: Geological dictionary . 10th edition, Enke Verlag, Stuttgart 1998, ISBN 3-432-84100-0 .

[Menning-3] see Menning et al .: A numerical time scale for the Pennsylvania in Central Europe. Courier Research Institute Senckenberg, Frankfurt / M. 2005, ISBN 3-510-61380-5 , p. 191.

[Richards-4] Barry C. Richards: Current Status of the International Carboniferous Time Scale. In SG Lucas et al. (editors) 2013: The Carboniferous-Permian Transition. New Mexico Museum of Natural History and Science Bulletin 60: 348-353. PDF

[Wagner-5] RH Wagner, CF Winkler Prins: The Cantabrian and Barruelian stratotypes: a summary of basin development and biostratigraphic information. In: Lemos de Sousa, MJ, Wagner, RH (Eds.): Papers on the Carboniferous of the Iberian Peninsula (Sedimentology, Stratigraphy, Paleontology, Tectonics and Geochemistry). Anais da Facultade de Ciencias, Supplement, 64 (Sp. Vol.), Universidade do Porto, 1985, pp. 359-410 online

[Doubinger-6] J. Doubinger, P. Vetter, J. Langiaux, J. Galtiert, J. Broutin: La flore fossile du bassin houiller de Saint-Étienne. Mémoires du Muséum National d'Histoire Naturelle, Paris 1995, ISBN 2-85653-218-7 , pp. 1-355 Abstract .