System	Subsystem/ Series	Stage	Age (Ma)
Permian	Cisuralian	Asselian	younger
Carboniferous	Pennsylvanian	Gzhelian	299.0–303.9
		Kasimovian	303.9–306.5
		Moscovian	306.5–311.7
		Bashkirian	311.7–318.1
	Mississippian	Serpukhovian	318.1–328.3
		Viséan	328.3–345.3
		Tournaisian	345.3–359.2
Devonian	Upper	Famennian	older
Subdivision of the Carboniferous system according to the ICS.[1]

The Bashkirian is in the ICS geologic timescale the lowest stage or oldest age of the Pennsylvanian, the youngest subsystem of the Carboniferous. The Bashkirian age lasted from 318.1 ± 1.3 to 311.7 ± 1.1 Ma,^[2] is preceded by the Serpukhovian and is followed by the Moscovian.

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.^[3]

Contents 1 Name and definition 2 Subdivision 3 See also 3.1 Notes 3.2 Literature 3.3 External links

[edit] Name and definition

The Bashkirian was named after the Bashkirs, inhabitants of the republic of Bashkortostan in the southern Ural Mountains (Russia). 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 nodiliferus. The top of the stage (the base of the Moscovian) is at the first appearance of the conodonts Declinognathodus donetzianus or Idiognathoides postsulcatus,^[4] or at the first appearance of fusulinid Aljutovella aljutovica.^[5] The GSSP (type location for the base of a stage) for the Bashkirian is in the Battleship Wash Formation at Arrow Canyon, Nevada.^[6]

[edit] Subdivision

The Bashkirian contains six biozones based on conodont index fossils:

• Neognathodus atokaensis Zone
• Declinognathodus marginodosus Zone
• Idiognathodus sinuosus Zone
• Neognathodus askynensis Zone
• Idiognathoides sinuatus Zone
• Declinognathodus noduliferus Zone

[edit] See also

[edit] Notes

[edit] Literature

• 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.
• 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.
• 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.
• Nemyrovska, T.I.; 1999: Bashkirian conodonts of the Donets Basin, Ukraine. Scr. Geol. 119, pp 1–115 (Russian).
• 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 (Russian).

[edit] External links

• Carboniferous timescale at the website of the Norwegian network of offshore records of geology and stratigraphy
• Bashkirian, Geowhen Database