The Visean, Viséan or Visian is an

age Age or AGE may refer to: Time and its effects * Age, the amount of time someone or something has been alive or has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...

in the ICS

geologic timescale The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronol ...

or a

stage Stage or stages may refer to: Acting * Stage (theatre), a space for the performance of theatrical productions * Theatre, a branch of the performing arts, often referred to as "the stage" * ''The Stage'', a weekly British theatre newspaper * Sta ...

in the

stratigraphic column A stratigraphic column is a representation used in geology and its subfield of stratigraphy to describe the vertical location of rock units in a particular area. A typical stratigraphic column shows a sequence of sedimentary rocks, with the oldest ...

. It is the second stage of the Mississippian, the lower

subsystem A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and expressed ...

of the

Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...

. The Visean lasted from to Ma. It follows the

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 Ma to Ma. It is preceded by the Famennian (the uppermost stage ...

age/stage and is followed by the

Serpukhovian The Serpukhovian is in the ICS geologic timescale the uppermost stage or youngest age of the Mississippian, the lower subsystem of the Carboniferous. The Serpukhovian age lasted from Ma to Ma. It is preceded by the Visean and is followed b ...

age/stage.

Name and definitions

The Viséan Stage was introduced by Belgian geologist

André Dumont André Dumont may refer to: * André Dumont (geologist) * André Dumont (politician) André Dumont (24 May 1764 at Oisemont – 19 October 1838 at Abbeville), was a French parliamentarian, a regicide, a deputy of the National Convention, Pres ...

in 1832. Dumont named this stage after the city of

Visé Visé (; nl, Wezet, ; wa, Vizé) is a city and municipality of Wallonia, located on the river Meuse in the province of Liège, Belgium. The municipality consists of the following districts: Argenteau, Cheratte, Lanaye, Lixhe, Richelle, ...

in Belgium's

Liège Province Liège (; wa, Lîdje ; nl, Luik ; german: Lüttich ) is the easternmost province of the Wallonia region of Belgium. Liège Province is the only Belgian province that has borders with three countries. It borders (clockwise from the north) the Du ...

. Before being used as an international stage, the Visean Stage was part of the (West) European regional geologic time scale, in which it followed the Tournaisian Stage and is followed by the Namurian Stage. In the North American regional scale, the Visean Stage correlates with the upper

Osagean The Mississippian ( , also known as Lower Carboniferous or Early Carboniferous) is a subperiod in the geologic timescale or a subsystem of the geologic record. It is the earlier of two subperiods of the Carboniferous period lasting from roughly ...

, the

Meramecian The Meramecian or Maramec stage is a sequence of Mississippian rocks in the Mississippi River Valley. It is named for the Meramec River in Missouri. Members Included are the St. Louis Limestone, Ste. Genevieve Limestone, Salem Limestone, and t ...

and lower Chesterian stages. In the Chinese regional time scale, it correlates with the lower and middle Tatangian series.; 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. The base of the Viséan Stage is at the first appearance of the fusulinid species '' Eoparastaffella simplex'' (

morphotype In biology, polymorphism is the occurrence of two or more clearly different morphs or forms, also referred to as alternative ''phenotypes'', in the population of a species. To be classified as such, morphs must occupy the same habitat at the s ...

1/morphotype 2). The type locality for the stage base used to be in a road section below the castle of

Dinant Dinant () is a City status in Belgium, city and Municipalities in Belgium, municipality of Wallonia located in the Namur Province, province of Namur, Belgium. On the shores of river Meuse, in the Ardennes, it lies south-east of Brussels, south ...

in Belgium, but this type locality proved to be insufficient for the purpose of stratigraphic correlation. A GSSP has been proposed in the Luzhai Formation near Penchong in the Chinese province of Guanxi. The top (the base of the Serpukhovian and Namurian) is laid at the first appearance of the

conodont Conodonts (Greek ''kōnos'', "cone", + ''odont'', "tooth") are an extinct group of agnathan (jawless) vertebrates resembling eels, classified in the class Conodonta. For many years, they were known only from their tooth-like oral elements, which ...

Lochriea ziegleri ''Lochriea'' is an extinct genus of conodonts. Use in stratigraphy The Visean, the second age of the Mississippian, contains four conodont biozones, two of which are named after ''Lochriea'' species: * the zone of ''Lochriea nodosa'' * the ...

'', or at the base of the biozone of goniatite '' Cravenoceras leion''.

Biota

The

Carboniferous-Earliest Permian Biodiversification Event The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...

began in the Viséan, coinciding with the start of the main phase of the Late Palaeozoic Ice Age. The late Viséan saw the widespread reappearance of metazoan reefs after their devastation during the

Hangenberg Event The Hangenberg event, also known as the Hangenberg crisis or end-Devonian extinction, is a mass extinction that occurred at the end of the Famennian stage, the last stage in the Devonian Period (roughly 358.9 ± 0.4 million years ago). It is usuall ...

. One of the tetrapods that lived during the Visean age was '' Westlothiana'', a reptile-like amphibian. Though originally thought to be the earliest discovered amniote, more recent research has cast doubt on this interpretation.

Biostratigraphy

The Visean contains four conodont biozones: * '' Lochriea nodosa'' Zone * '' Lochriea mononodosa'' Zone * '' Gnathodus bilineatus'' Zone * '' Gnathodus texanus'' Zone In British stratigraphy, the Visean is subdivided into five substages. These are from bottom to top: Chadian (the lower part of this substage falls in the Tournaisian), Arundian,

Holkerian The Holkerian is a sub-stage of the Viséan stage of the International Commission on Stratigraphy (ICS) geological timescale. It is one of five sub-stages commonly used in the Viséan stage within stratigraphy by British, Irish and other geologists ...

, Asbian and Brigantian.; 2006: ''The Carboniferous system, use of the new official names for the subsystems, series and stages'', Geologica Acta 4(3), pp 403–407.

References

External links

Upper
an
lower
time scales for the Carboniferous at the website of the Norwegian network of offshore records of geology and stratigraphy

www.palaeos.com {{DEFAULTSORT:Visean Mississippian geochronology Geological ages . Stratigraphy of Europe

Name and definitions

Biota

Biostratigraphy

References

Further reading

External links