Visa

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system Subsystem step ≈ age ( mya )
higher higher higher younger
Carbon Pennsylvania Gzhelium 298.9
⬍
303.7
Kasimovium 303.7
⬍
307
Moskovium 307
⬍
315.2
Bashkirium 315.2
⬍
323.2
Mississippium Serpukhovium 323.2
⬍
330.9
Visa 330.9
⬍
346.7
Tournaisium 346.7
⬍
358.9
deeper deeper deeper older

The Viséum (mostly shortened to Visé in German ) is a time period of the Carboniferous ( Paleozoic ) in the history of the earth . In the chronostratigraphic subdivision of the Carboniferous it is the second stage of the Mississippian subsystem and the only stage of the Middle Mississippian series . Expressed in absolute numbers ( geochronologically ) it is the period from about 346.7 to 330.9 million years. The level follows the Tournaisium level and is replaced by the Serpukhovium level.

Naming and history

The stage is named after the city of Visé in Belgium . The subdivision of the Central European Lower Carboniferous (or Dinantium ) goes back to André Hubert Dumont (1832). But only Laurent-Guillaume de Koninck (1842-44) named the two parts with "calcaire carbonifère de Tournai" and "calcaire carbonifère de Visé". It was primarily a lithostratigraphic subdivision. In 1860 Gosselet led the "étage du calcaire de Visé". In the legend of the six sheets of the Geological Map of Belgium (Dupont, 1882–1883) it became the “étage de Visé”.

Definition and GSSP

The base of the stage is defined by the first appearance of the fusulin species Eoparastaffella simplex ( Morphotype 1 / Morphotype 2). The conodont species Gnathodus homopunctatus begins only 10 cm above this limit. The upper limit of the viséum or the lower limit of the Serpukhovium is defined by the first appearance of the conodont species Lochriea ziegleri . The official reference profile of the International Commission on Stratigraphy ( Global Stratotype Section and Point ) for the Visa was ratified in 2008 and is located near Pengchong (South China, 24.4333 ° N, 109.4500 ° E). The lower limit of the Visa is in the Pengchong profile at the base of Bank 83.

Regional breakdown

The viséum was originally a regional level that was used almost exclusively in Europe. Outside Europe, other levels of subdivision of the Lower Carboniferous were in use. With the ratification of the viséum and the establishment of a GSSP , the viséum became a global stage. In Europe, it was further divided into sub-levels depending on the region. In Germany it corresponds to the higher part of the Erdbachium and the Aprathium ; both lower levels are rather uncommon today. In Belgium the viséum corresponds to the Moliniacium , Livium and Warnantium . In England it is correlated with the higher part of the Chadium , the Arundium , the Holkerium , the Asbium and the Brigantium . In other regions (e.g. North America, Russia) further regional breakdowns are used.

Biostratigraphic breakdown

The Viseum is divided into four conodont bio-zones:

It correlates with the foraminifera interval zones MFZ9 to MFZ15 of the Mississippian.

In the stratigraphic sequence of rugose corals it correlates with the higher part of the RC4 to RC8 zone.

swell

literature

  • André Hubert Dumont: Mémoire sur la constitution géologique de la province de Liège. In: Mémoires couronnés par l'Académie Royale des Sciences et Belles-Lettres de Bruxelles. 8 (3): VII, 374 pp., Brussels 1832.
  • Felix Gradstein, Jim Ogg, Jim & Alan Smith: A Geologic Timescale. Cambridge University Press 2004, ISBN 978-0-521-78673-7 .
  • Luc Hance, Edouard Poty and François-Xavier Devust: Viséan. Geologica Belgica, 9 (1-2): 55-62, Brussels 2006 PDF .
  • Hans Murawski & Wilhelm Meyer: Geological dictionary . 10., rework. u. exp. Ed., 278 pages, Enke Verlag, Stuttgart 1998, ISBN 3-432-84100-0 .

Individual evidence

  1. ↑ Hance et al. (2006: p. 55ff.)
  2. ↑ [Timescale Creator by Jim Ogg and Adam Lugowski Archived copy ( memento of the original from January 29, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. ] @1@ 2Template: Webachiv / IABot / www.tscreator.com
  3. ↑ Édouard Poty, François-Xavier Devuyst and Luc Hance: Upper Devonian and Mississippian foraminiferal and rugose coral zonations of Belgium and northern France: a tool for Eurasian correlations. Geological Magazine, 143 (6): 829-857, Oxford 2006 doi: 10.1017 / S0016756806002457

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