Tournaisium

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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 Tournaisium (in German usage mostly shortened to Tournai) is a period of the Carboniferous ( Paleozoic ) in the history of the earth . In chronostratigraphy it is the lowest stage of the Mississippian or the only stage of the lower Mississippian series . Geochronologically, the stage covers the period from about 358.9 million to about 346.7 million years. The level follows the Famennium level of the Devonian and is superseded by the Viséum level of the carbon.

Naming and history

The stage is named after the town of Tournai (Doornik) in Belgium . The subdivision of Central European lower carbon (or dinantium ) into two levels goes back to André Hubert Dumont (1832). Laurent-Guillaume de Koninck (1842–44) named these two parts "calcaire carbonifère de Tournai" and "calcaire carbonifère de Visé". It was primarily a lithostratigraphic subdivision. In 1860 Gosselet ran the "étage du calcaire de Tournai". In the legend of the six sheets of the Geological Map of Belgium (Dupont, 1882–1883) it became the "étage de Tournai".

Definition and GSSP

The base of the stage is defined by the first appearance of the conodont species Siphonodella sulcata within the line of development from Siphonodella praesulcata to Siphonodella sulcata . The boundary was placed at the base of bench 89 of the La Serre profile. The upper limit of the level is marked by the first appearance of the fusulin species Eoparastaffella simplex ( Morphotype 1 / Morphotype 2). The official reference profile of the International Commission for Stratigraphy ("Global Stratotype Section and Point" = GSSP) for the Tournaisium is the La Serre profile in the southeastern Montagne Noire ( France ). It is a cut about 80 cm deep on the southern slope of Mount La Serre, about 125 m south of the summit (252 m), about 525 m east of Maison La Roquette, in the area of Cabrières , 2.5 km northeast of the village of Fontès ( Hérault ), France).

According to more recent investigations, the conodont species Siphonodella sulcata already begins at the base of bank 85 of the La Serre profile. The original GSSP and the first appearance of the conodont species Siphonodella sulcata therefore no longer exactly match.

Regional breakdown

The Tournaisium was originally a regional level that was used almost exclusively in Central and Western Europe. Other subdivisions of carbon were used in other regions. In 1990 the Tournaisium was ratified as a global stage by the International Commission on Stratigraphy of the International Union of Geological Sciences (IUGS). In Central and Western Europe, the Tournaisium is subdivided into different sub-levels depending on the region. In Germany it correlates with the balvium and the lower part of the Erdbachium ; both sub-levels are rarely used today. In Belgium it is divided into the Hastarium and Ivorium lower grades . In England it correlates with the lower grade Courceyium and the lower part of the Chadium . In other regions, further regional levels and sub-levels are used to structure the Mississippium.

Biostratigraphic breakdown

The tournaisium is subdivided into eight conodont biozones:

It correlates with the MFZ1 to MFZ8 of the foraminifera interval zones of the Mississippium. In the zoning of rugose corals , it corresponds to zones RC1 to RC3 and the lower part of the RC4 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), Brussels 1832, p. VII.
  • Felix Gradstein, Jim Ogg, Jim & Alan Smith: A Geologic timescale. Cambridge University Press, 2004, ISBN 0-521-78673-8 .
  • Luc Hance, Edouard Poty, François-Xavier Devust: Tournaisian. In: Geologica Belgica. 9 (1-2), Brussels 2006, pp. 47-53. (PDF)
  • Hans Murawski, Wilhelm Meyer: Geological dictionary. 10., rework. u. exp. Edition. Enke Verlag, Stuttgart 1998, ISBN 3-432-84100-0 .
  • E. Paproth, R. Feist, G. Flaijs: Decision on the Devonian-Carboniferous boundary stratotype. In: Episodes. 14 (4), Beijing 1991, pp. 331-336. ISSN  0705-3797
  • Dieter Stoppel, Michael RW Amler: To the delimitation and subdivision of the lower carbon. In: Stratigraphy of Germany VI Lower Carboniferous (Mississippian). (= Series of publications of the German Society for Geosciences. 41). Hannover 2006, ISBN 3-932537-37-8 , pp. 15-26.

Individual evidence

  1. ↑ Hance et al. (2006, p. 47ff.)
  2. ^ GSSP Table - Paleozoic Era Subcommission for Stratigraphic Information
  3. ↑ Timescale Creator by Jim Ogg and Adam Lugowski tscreator.com ( memento of the original from January 29, 2010 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.tscreator.com
  4. ↑ Édouard Poty, François-Xavier Devuyst, Luc Hance: Upper Devonian and Mississippian foraminiferal and rugose coral zonations of Belgium and northern France: a tool for Eurasian correlations. In: Geological Magazine. 143 (6), Oxford 2006, pp. 829-857. doi: 10.1017 / S0016756806002457

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