Tournaisian

The Tournaisian is in the ICS geologic timescale the lowest stage or oldest age of the Mississippian, the oldest subsystem of the Carboniferous. The Tournaisian age lasted from 358.9 Ma to 346.7 Ma.[3] It is preceded by the Famennian (the uppermost stage of the Devonian) and is followed by the Viséan.

Tournaisian
358.9 ± 0.4 – 346.7 ± 0.4 Ma
Chronology
Key events in the Carboniferous
-360 —
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-355 —
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-350 —
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-345 —
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-340 —
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-335 —
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-330 —
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-325 —
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-320 —
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-315 —
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-310 —
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-305 —
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-300 —
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Key events of the Carboniferous Period
Axis scale: millions of years ago
Etymology
Name formalityFormal
Usage Information
Celestial bodyEarth
Regional UsageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitAge
Stratigraphic unitStage
Time span formalityFormal
Lower boundary definitionFAD of the Conodont Siphonodella sulcata (discovered to have biostratigraphic issues as of 2006).[1]
Lower boundary GSSPLa Serre, Montagne Noire, France
43.5555°N 3.3573°E / 43.5555; 3.3573
GSSP ratified1990[2]
Upper boundary definitionFAD of the Benthic Foraminifer Eoparastaffella simplex
Upper boundary GSSPPengchong Section, Guangxi, China
24.4333°N 109.4500°E / 24.4333; 109.4500
GSSP ratified2008

Name and regional alternatives

The Tournaisian was named after the Belgian city of Tournai. It was introduced in scientific literature by Belgian geologist André Hubert Dumont in 1832. Like many Devonian and lower Carboniferous stages, the Tournaisian is a unit from West European regional stratigraphy that is now used in the official international time scale.

The Tournaisian correlates with the regional North American Kinderhookian and lower Osagean stages and the Chinese Tangbagouan regional stage. In British stratigraphy, the Tournaisian contains three substages: the Hastarian, Ivorian and lower part of the Chadian (the upper part falls in the Viséan).[4]

Stratigraphy

The base of the Tournaisian (which is also the base of the Carboniferous system) is at the first appearance of the conodont Siphonodella sulcata within the evolutionary lineage from Siphonodella praesulcata to Siphonodella sulcata. The first appearance of ammonite species Gattendorfia subinvoluta is just above this and was used as a base for the Carboniferous in the past.[5] The GSSP for the Tournaisian is near the summit of La Serre hill, in the commune of Cabrières, in the Montagne Noire (southern France).[6] The GSSP is in a section on the southern side of the hill, in an 80 cm deep trench, about 125 m south of the summit, 2.5 km southwest of the village of Cabrières and 2.5 km north of the hamlet of Fontès.

The top of the Tournaisian (the base of the Viséan) is at the first appearance of the fusulinid species Eoparastaffella simplex (morphotype 1/morphotype 2).

The Tournaisian contains eight conodont biozones:

The Tournaisian coincides with Romer's gap, a period of remarkable little terrestrial fossils, thus constituting a discontinuity between the Devonian and the more modern terrestrial ecosystems of the Carboniferous.

Tournaisian life

Fish
Fish of the Tournaisian
Taxa Presence Location Description Images
Stethacanthus

Tetrapodomorpha
Tetrapodomorphs of the Tournaisian
Taxa Presence Location Description Images
Barameda Australia A very large basal tetrapodomorph fish in the family Rhizodontidae. One of the largest freshwater fish to ever live, it reached lengths of over 6 meters rivaling in size its relative Rhizodus.
Occidens Northern Ireland A genus of stem tetrapod. Originally attributed to the lobe-finned fish Holoptychius a later phylogenetic analysis found Occidens it be the closest relative of Sigournea multidentata.
Pederpes Ivorian Ballagan Formation, Scotland A medium sized stegocephalian stem tetrapod in the family Whatcheeriidae.

References
  1. Kaiser 2009.
  2. Paproth, Feist & Flajs 1991.
  3. Gradstein et al. (2004)
  4. Heckel & Clayton (2006)
  5. Menning et al. (2006); for the old definition, see Paeckelmann & Schindewolf (1937)
  6. The GSSP was published by Paproth et al. (1991)

Literature
  • Dumont, A.H.; 1832: Mémoire sur la constitution géologique de la province de Liège, Mémoires couronnés par l'Académie Royale des Sciences et Belles-Lettres de Bruxelles 8(3), VII. (in French)
  • Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
  • Heckel, P.H. & Clayton, G.; 2006: The Carboniferous system, use of the new official names for the subsystems, series and stages, Geologica Acta 4(3), pp 403–407.
  • Menning, M.; Alekseev, A.S.; Chuvashov, B.I.; Davydov, V.I.; Devuyst, F.-X.; Forke, H.C.; Grunt, T.A.; Hance, L.; Heckel, P.H.; Izokh, N.G.; Jin, Y.-G.; Jones, P.J.; Kotlyar, G.V.; Kozur, H.W.; Nemyrovska, T.I.; Schneider, J.W.; Wang, X.-D.; Weddige, K.; Weyer, D. & Work, D.M.; 2006: Global time scale and regional stratigraphic reference scales of Central and West Europe, East Europe, Tethys, South China, and North America as used in the Devonian–Carboniferous–Permian Correlation Chart 2003 (DCP 2003), Palaeogeography, Palaeoclimatology, Palaeoecology 240(1-2): pp 318–372.
  • Paeckelmann, W. & Schindewolf, O.H.; 1937: Die Devon-Karbon-Grenze, Comptes Rendus (2) du Cinquième Congrès International de Stratigraphie et Géologie du Carbonifère, Heerlen 1935 (2), pp 703–714. (in German)
  • Paproth, E.; Feist, R. & Flajs, G.; 1991: Decision on the Devonian–Carboniferous Boundary Stratotype, Episodes 14(4), pp 331–336.

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