Bashkirian

Fourth stage of the Carboniferous From Wikipedia, the free encyclopedia

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 323.4 to 315.2 Ma,[3] is preceded by the Serpukhovian and is followed by the Moscovian.

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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
36.7333°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)
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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

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