Bashkirian

This article is about the stage of the Carboniferous. For the defunct Russian airline, see BAL Bashkirian Airlines.

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.

Bashkirian
323.2 ± 0.4 – 315.2 ± 0.2 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Chronology
−360 — – −355 — – −350 — – −345 — – −340 — – −335 — – −330 — – −325 — – −320 — – −315 — – −310 — – −305 — – −300 — – Paleozoic D Carboniferous P Mississippian Pennsylvanian LD Early Middle Late Early Mid Late CS Famennian Tournaisian Viséan Serpukhovian Bashkirian Moscovian Kasimovian Gzhelian Asselian     ← Carboniferous Rainforest Collapse ← Mazon Creek Fossils ← End of Romer's Gap ← Start of Romer's Gap Subdivision of the Carboniferous according to the ICS, as of 2023.[1] Vertical axis scale: Millions of years ago
Etymology
Name formality	Formal
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Age
Stratigraphic unit	Stage
Time span formality	Formal
Lower boundary definition	FAD of the Conodont Declinognathodus nodiliferus
Lower boundary GSSP	Arrow Canyon, Nevada, USA 36.7333°N 114.7778°W / 36.7333; -114.7778
Lower GSSP ratified	1996[2]
Upper boundary definition	Not formally defined
Upper boundary definition candidates	FAD of the Conodont Idiognathoides postsulcatus or Declinognathodus donetzianus
Upper boundary GSSP candidate section(s)	Southern Ural Mountains Nashui, Luodian County, Guizhou, China

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 lower Bird Spring Formation at Arrow Canyon, Nevada.^[7]

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