Bashkirian

{{short description|Fourth stage of the Carboniferous}} {{About|the stage of the Carboniferous|the defunct Russian airline|BAL Bashkirian Airlines}} {{Infobox geologic timespan | name = Bashkirian | color = Bashkirian | time_start = 323.4 | time_start_uncertainty = 0.4 | time_end = 315.2 | time_end_uncertainty = 0.2 | image_map = File:320Ma Mollweide.png | caption_map = Mollweide map of Earth 320 million years ago, with black outlines depicting countries in their locations | image_outcrop = | caption_outcrop = | image_art = | caption_art =  | timeline = Carboniferous | formerly_part_of = | partially_contained_in = | partially_contains =  | name_formality = Formal | name_accept_date = | alternate_spellings = | synonym1 = | synonym1_coined = | synonym2 = | synonym2_coined = | synonym3 = | synonym3_coined = | nicknames = | former_names = | proposed_names =  | celestial_body = earth | usage = Global (ICS) | timescales_used = ICS Time Scale | formerly_used_by = | not_used_by =  | chrono_unit = Age | strat_unit = Stage | proposed_by = | type_section = | timespan_formality = Formal | lower_boundary_def = FAD of the Conodont ''Declinognathodus nodiliferus'' | lower_gssp_location = Arrow Canyon, Nevada, USA | lower_gssp_coords = {{Coord|36.7333|N|114.7778|W|display=inline}} | lower_gssp_accept_date = 1996<ref>{{cite journal |last1=Lane |first1=H. |last2=Brenckle |first2=Paul |last3=Baesemann |first3=J. |last4=Richards |first4=Barry |title=The IUGS boundary in the middle of the Carboniferous: Arrow Canyon, Nevada, USA |journal=Episodes |date=December 1999 |volume=22 |issue=4 |pages=272–283 |doi=10.18814/epiiugs/1999/v22i4/003 |doi-access=free }}</ref> | upper_boundary_def = Not formally defined | upper_def_candidates = FAD of the Conodont ''Idiognathoides postsulcatus'' or ''Declinognathodus donetzianus'' | upper_gssp_candidates = * Southern Ural Mountains * Nashui, Luodian County, Guizhou, China  | o2 = | co2 = | temp = | sea_level = }}

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 {{Period start|Bashkirian}} to {{Period start|Moscovian}} Ma,<ref>{{aut|Gradstein, F.M.; Ogg, J.G. & Smith, A.G.}}; '''2004''': ''A Geologic Time Scale 2004'', Cambridge University Press.</ref> 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.<ref>{{aut|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. </ref>

==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'',<ref>{{aut|Nemyrovska, T.I.}}; '''1999''': ''Bashkirian conodonts of the Donets Basin'', Ukraine. Scr. Geol. '''119''', pp 1–115 {{in lang|ru}}.</ref> or at the first appearance of fusulinid ''Aljutovella aljutovica''.<ref>{{aut|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 lang|ru}}.</ref> The GSSP (type location for the base of a stage) for the Bashkirian is in the lower Bird Spring Formation at Arrow Canyon, Nevada.<ref>{{aut|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.</ref>

==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

==References== {{reflist}}

===Literature=== *{{aut|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.

==External links== *[https://web.archive.org/web/20060518101823/http://norges.uio.no/timescale/Fig14.1_Carbon-colA.pdf Carboniferous timescale] at the website of the Norwegian network of offshore records of geology and stratigraphy *[https://web.archive.org/web/20090422155859/http://www.stratigraphy.org/bak/geowhen/stages/Bashkirian.html ''Bashkirian'', Geowhen Database] {{Geological history|p|p}}

Category:Bashkirian Category:Pennsylvanian geochronology