Tournaisian
Encyclopedia
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 359.2 ± 2.5 Ma to 345.3 ± 2.1 Ma. It is preceded by the Famennian
(the uppermost stage of the Devonian
) and is followed by the Viséan
.
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).
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. The GSSP for the Tournaisian is near the summit of La Serre
in the Montagne Noire
(southern France
). The GSSP is in a section on the southern side of the mountain, in an 80 cm deep trench, about 125 m south of the summit, 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 biozone
s:
The Tournaisian coincide with Romer's gap
, a period of remarkable little terrestrial fossils, thus constituting a discontinuity between the Devonian
and the more modern terrestrial ecosystem
s of the Carboniferous.
International Commission on Stratigraphy
The International Commission on Stratigraphy , sometimes referred to by the unofficial "International Stratigraphic Commission" is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigraphy, geological, and geochronological matters on a global...
geologic timescale the lowest stage or oldest age of the Mississippian, the oldest subsystem of the Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
. The Tournaisian age lasted from 359.2 ± 2.5 Ma to 345.3 ± 2.1 Ma. It is preceded by the Famennian
Famennian
The Famennian is one of two faunal stages in the Late Devonian epoch. It lasted from 374.5 ± 2.6 million years ago to 359.2 ± 2.5 million years ago. It was preceded by the Frasnian stage and followed by the Tournaisian stage and is named after Famenne, a natural region in southern Belgium.It was...
(the uppermost stage of the Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
) and is followed by the Viséan
Viséan
The Visean, Viséan or Visian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the second stage of the Mississippian, the lower subsystem of the Carboniferous. The Visean lasted from 345.3 ± 2.1 to 328.3 ± 1.6 Ma...
.
Name and regional alternatives
The Tournaisian was named after the BelgianBelgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
city of Tournai
Tournai
Tournai is a Walloon city and municipality of Belgium located 85 kilometres southwest of Brussels, on the river Scheldt, in the province of Hainaut....
. 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).
Stratigraphy
The base of the Tournaisian (which is also the base of the Carboniferous system) is at the first appearance of the conodontConodont
Conodonts are extinct chordates resembling eels, classified in the class Conodonta. For many years, they were known only from tooth-like microfossils now called conodont elements, found in isolation. Knowledge about soft tissues remains relatively sparse to this day...
Siphonodella sulcata within the evolutionary lineage
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
from Siphonodella praesulcata to Siphonodella sulcata. The first appearance of ammonite
Ammonite
Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct subclass within the Molluscan class Cephalopoda which are more closely related to living coleoids Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct...
species Gattendorfia subinvoluta is just above this and was used as a base for the Carboniferous in the past. The GSSP for the Tournaisian is near the summit of La Serre
La Serre
La Serre is a commune in the Aveyron department in southern France.-Population:-References:*...
in the Montagne Noire
Montagne Noire
* Not to be confused with the Montagnes Noires in Brittany.The Montagne Noire is a mountain range in central southern France. It is located at the southwestern end of the Massif Central in the border area of the Tarn, Hérault and Aude departments...
(southern France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
). The GSSP is in a section on the southern side of the mountain, in an 80 cm deep trench, about 125 m south of the summit, 2.5 km north of the hamlet of Fontès
Fontès
Fontès is a commune in the Hérault department in southern France....
.
The top of the Tournaisian (the base of the Viséan) is at the first appearance of the fusulinid
Fusulinid
The Fusulinida is an extinct order within the Foraminifera in which the tests are composed of tightly packed, secreted microgranular calcite. In advanced forms the test wall is differentiated into two or more layers...
species Eoparastaffella simplex (morphotype 1/morphotype 2).
The Tournaisian contains eight conodont biozone
Biozone
Biostratigraphic units or Biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa....
s:
- the zone of Gnathodus pseudosemiglaber and Scaliognathus anchoralis
- the zone of Gnathodus semiglaber and Polygnathus communis
- the zone of Dollimae bouckaerti
- the zone of Gnathodus typicus and Siphonodella isosticha
- the zone of Siphonodella quadruplicata and Patrognathus andersoni (upper zone of Patrognathus andersoni)
- the lower zone of Patrognathus andersoni
- the zone of Patrognathus variabilis
- the zone of Patrognathus crassus
The Tournaisian coincide with Romer's gap
Romer's gap
Romer's Gap is an example of a gap in the fossil record used in the study of evolution. Such gaps represent a period from which excavators have found no or very few fossils. Romer's gap is named after paleontologist Dr...
, a period of remarkable little terrestrial fossils, thus constituting a discontinuity between the Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
and the more modern terrestrial ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
s of the Carboniferous.
Literature
; 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. ; 2004: A Geologic Time Scale 2004, Cambridge University Press.; 2006: The Carboniferous system, use of the new official names for the subsystems, series and stages, Geologica Acta 4(3), pp 403-407.; 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.; 1937: Die Devon-Karbon-Grenze, Comptes Rendus (2) du Cinquième Congrès International de Stratigraphie et Géologie du Carbonifère, Heerlen 1935 (2), pp 703–714. ; 1991: Decision on the Devonian–Carboniferous Boundary Stratotype, Episodes 14(4), pp 331–336.External links
- Early Carboniferous timescale at the website of the Norwegian network of offshore records of geology and stratigraphy
- Tournaisian, Geowhen Database
- The Tournaisian age, www.palaeos.com