Bashkirian

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Bashkirian
323.2 ± 0.4 – 315.2 ± 0.2 Ma
Chronology
Etymology
Name formalityFormal
Usage information
Celestial body Earth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unit Age
Stratigraphic unit Stage
Time span formalityFormal
Lower boundary definition FAD of the Conodont Declinognathodus nodiliferus
Lower boundary GSSP Arrow Canyon, Nevada, USA
36°44′00″N114°46′40″W / 36.7333°N 114.7778°W / 36.7333; -114.7778
Lower GSSP ratified1996 [2]
Upper boundary definitionNot formally defined
Upper boundary definition candidatesFAD of the Conodont Idiognathoides postsulcatus or Declinognathodus donetzianus
Upper boundary GSSP candidate section(s)

The Bashkirian is in the International Commission on Stratigraphy geologic timescale the lowest stage or oldest age of the Pennsylvanian. The Bashkirian age lasted from 323.2 to 315.2 Ma, [3] is preceded by the Serpukhovian and is followed by the Moscovian.

Contents

The Bashkirian overlaps with the upper part of the Namurian and lower part of the Westphalian stages from regional European stratigraphy. It also overlaps with the North American Morrowan and Atokan stages and the Chinese Luosuan and lower Huashibanian stages. [4]

Name and definition

The Bashkirian was named after Bashkiria, the then Russian name of the republic of Bashkortostan in the southern Ural Mountains of Russia, home of the Bashkir people. The stage was introduced by Russian stratigrapher Sofia Semikhatova in 1934.

The base of the Bashkirian is at the first appearance of conodont species Declinognathodus noduliferus. The top of the stage (the base of the Moscovian) is at the first appearance of the conodonts Declinognathodus donetzianus or Idiognathoides postsulcatus, [5] or at the first appearance of fusulinid Aljutovella aljutovica. [6] The GSSP (type location for the base of a stage) for the Bashkirian is in the Battleship Wash Formation at Arrow Canyon, Nevada. [7]

Subdivision

The Bashkirian contains six biozones based on conodont index fossils:

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<span class="mw-page-title-main">Tournaisian</span> First stage of the Carboniferous

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. It is preceded by the Famennian and is followed by the Viséan. In global stratigraphy, the Tournaisian contains two substages: the Hastarian and Ivorian. These two substages were originally designated as European regional stages.

<span class="mw-page-title-main">Viséan</span> Second stage of the Carboniferous

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 346.7 to 330.9 Ma. It follows the Tournaisian age/stage and is followed by the Serpukhovian age/stage.

<span class="mw-page-title-main">Serpukhovian</span> Third stage of the Carboniferous

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 330.9 Ma to 323.2 Ma. It is preceded by the Visean and is followed by the Bashkirian. The Serpukhovian correlates with the lower part of the Namurian Stage of European stratigraphy and the middle and upper parts of the Chesterian Stage of North American stratigraphy.

The Kasimovian is a geochronologic age or chronostratigraphic stage in the ICS geologic timescale. It is the third stage in the Pennsylvanian, lasting from 307 to 303.7 Ma. The Kasimovian Stage follows the Moscovian and is followed by the Gzhelian. The Kasimovian saw an extinction event which occurred around 305 mya, referred to as the Carboniferous Rainforest Collapse. It roughly corresponds to the Missourian in North American geochronology and the Stephanian in western European geochronology.

<span class="mw-page-title-main">Gzhelian</span> Seventh and final stage of the Carboniferous

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The Moscovian is in the ICS geologic timescale a stage or age in the Pennsylvanian, the youngest subsystem of the Carboniferous. The Moscovian age lasted from 315.2 to 307 Ma, is preceded by the Bashkirian and is followed by the Kasimovian. The Moscovian overlaps with the European regional Westphalian stage and the North American Atokan and Desmoinesian stages.

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Neognathodus is an extinct genus of conodonts.

Declinognathodus is an extinct genus of platform conodonts.

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References

  1. "Chart/Time Scale". www.stratigraphy.org. International Commission on Stratigraphy.
  2. Lane, H.; Brenckle, Paul; Baesemann, J.; Richards, Barry (December 1999). "The IUGS boundary in the middle of the Carboniferous: Arrow Canyon, Nevada, USA". Episodes. 22 (4): 272–283. doi: 10.18814/epiiugs/1999/v22i4/003 .
  3. Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
  4. 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.
  5. Nemyrovska, T.I.; 1999: Bashkirian conodonts of the Donets Basin, Ukraine. Scr. Geol. 119, pp 1–115 (in Russian).
  6. Solovieva, M.N.; 1986: Zonal fusulinid scale of the Moscovian Stage based on a revision of the type sections of intrastage subdivisions, Vopr. Mikropaleontol. 28, pp 3–23 (in Russian).
  7. Lane, H.R.; Brenckle, P.L.; Baesemann, J.F. & Richards, B.; 1999: The IUGS boundary in the middle of the Carboniferous: Arrow Canyon, Nevada, USA, Episodes 22(4), pp 272–283.

Literature

36°44′00″N114°46′40″W / 36.7333°N 114.7778°W / 36.7333; -114.7778