Bashkirian
| System | Subsystem/ Series |
Stage | Age (Ma) | ||
|---|---|---|---|---|---|
| Permian | Cisuralian | Asselian | younger | ||
| Carboniferous | Pennsylvanian | Gzhelian | 298.9–303.7 | ||
| Kasimovian | 303.7–307.0 | ||||
| Moscovian | 307.0–315.2 | ||||
| Bashkirian | 315.2–323.2 | ||||
| Mississippian | Serpukhovian | 323.2–330.9 | |||
| Viséan | 330.9–346.7 | ||||
| Tournaisian | 346.7–358.9 | ||||
| Devonian | Late | 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 Bashkirian age lasted from 323.2 ± 0.4 to 315.2 ± 0.2 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]
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,[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]
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
See also
Notes
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).
External links
- Carboniferous timescale at the website of the Norwegian network of offshore records of geology and stratigraphy
- Bashkirian, Geowhen Database
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