Bashkirian
323.2 ± 0.4 – 315.2 ± 0.2 Ma
Chronology
Etymology
Name formalityFormal
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitAge
Stratigraphic unitStage
Time span formalityFormal
Lower boundary definitionFAD of the Conodont Declinognathodus nodiliferus
Lower boundary GSSPArrow Canyon, Nevada, USA
36°44′00″N 114°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.

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:

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

External links

36°44′00″N 114°46′40″W / 36.7333°N 114.7778°W / 36.7333; -114.7778

Geological history of Earth
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