Fourth stage of the Carboniferous
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 to Ma, 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.
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", or at the first appearance of fusulinid "Aljutovella aljutovica". The GSSP (type location for the base of a stage) for the Bashkirian is in the Battleship Wash Formation at Arrow Canyon, Nevada.
Subdivision.
The Bashkirian contains six biozones based on conodont index fossils:
References.
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