Editing Permian (section)

==Geology==
The Permian Period is divided into three [[Epoch (geology)|epochs]], from oldest to youngest, the Cisuralian, Guadalupian, and Lopingian. Geologists divide the rocks of the Permian into a [[Stratigraphy|stratigraphic]] set of smaller units called [[Stage (stratigraphy)|stages]], each formed during corresponding time intervals called ages. Stages can be defined globally or regionally. For ''global'' stratigraphic correlation, the [[International Commission on Stratigraphy]] (ICS) ratify global stages based on a [[Global Boundary Stratotype Section and Point]] (GSSP) from a single [[Formation (geology)|formation]] (a [[stratotype]]) identifying the lower boundary of the stage. The ages of the Permian, from youngest to oldest, are:<ref name="Cohen-2013">Cohen, K.M., Finney, S.C., Gibbard, P.L. & Fan, J.-X. (2013; updated) [https://stratigraphy.org/ICSchart/ChronostratChart2023-04.pdf The ICS International Chronostratigraphic Chart] {{Webarchive|url=https://web.archive.org/web/20230528121713/https://stratigraphy.org/ICSchart/ChronostratChart2023-04.pdf |date=2023-05-28 }}. Episodes 36: 199–204.</ref>
{|
!Epoch
!Stage
!Lower boundary<br>(Ma)
|-
| style="background-color: {{period color|Early Triassic}}; color:white;" |Early Triassic
| style="background-color: {{period color|Induan}}; color:white;" |Induan
|251.902 ±0.024
|-
| rowspan="2" style="background-color: {{period color|Lopingian}};" |[[Lopingian]]
| style="background-color: {{period color|Changhsingian}};" |[[Changhsingian]]
|254.14 ±0.07
|-
| style="background-color: {{period color|Wuchiapingian}};" |[[Wuchiapingian]]
|259.51 ±0.21
|-
| rowspan="3" style="background-color: {{period color|Guadalupian}};" |[[Guadalupian]]
| style="background-color: {{period color|Capitanian}};" |[[Capitanian]]
|264.28 ±0.16
|-
| style="background-color: {{period color|Wordian}};" |[[Wordian]]
|266.9 ±0.4
|-
| style="background-color: {{period color|Roadian}};" |[[Roadian]]
|273.01 ±0.14
|-
| rowspan="4" style="background-color: {{period color|Cisuralian}} " |[[Cisuralian]]
| style="background-color: {{period color|Kungurian}};" |[[Kungurian]]
|283.5 ±0.6 
|-
| style="background-color: {{period color|Artinskian}};" |[[Artinskian]]
|290.1 ±0.26
|-
| style="background-color: {{period color|Sakmarian}};" |[[Sakmarian]]
|293.52 ±0.17
|-
| style="background-color: {{period color|Asselian}};" |[[Asselian]]
|298.9 ±0.15
|}
For most of the 20th century, the Permian was divided into the Early and Late Permian, with the Kungurian being the last stage of the Early Permian.<ref name="Olroyd-2017">{{Cite journal|last1=Olroyd|first1=Savannah L.|last2=Sidor|first2=Christian A.|date=August 2017|title=A review of the Guadalupian (middle Permian) global tetrapod fossil record|journal=Earth-Science Reviews|language=en|volume=171|pages=583–597|doi=10.1016/j.earscirev.2017.07.001|bibcode=2017ESRv..171..583O|doi-access=free}}</ref> Glenister and colleagues in 1992 proposed a tripartite scheme, advocating that the Roadian-Capitanian was distinct from the rest of the Late Permian, and should be regarded as a separate epoch.<ref>{{Cite journal|last1=Glenister|first1=Brian F.|last2=Boyd|first2=D. W.|last3=Furnish|first3=W. M.|last4=Grant|first4=R. E.|last5=Harris|first5=M. T.|last6=Kozur|first6=H.|last7=Lambert|first7=L. L.|last8=Nassichuk|first8=W. W.|last9=Newell|first9=N. D.|last10=Pray|first10=L. C.|last11=Spinosa|first11=C.|title=The Guadalupian: Proposed International Standard for a Middle Permian Series|date=September 1992|url=https://www.tandfonline.com/doi/full/10.1080/00206819209465642|journal=International Geology Review|language=en|volume=34|issue=9|pages=857–888|doi=10.1080/00206819209465642|bibcode=1992IGRv...34..857G|issn=0020-6814}}</ref> The tripartite split was adopted after a formal proposal by Glenister et al. (1999).<ref>Glenister BF., Wardlaw BR., Lambert LL., Spinosa C., Bowring SA., Erwin DH., Menning M., Wilde GL. 1999. Proposal of Guadalupian and component Roadian, Wordian and Capitanian stages as international standards for the middle Permian series. Permophiles 34:3-11</ref>

Historically, most marine biostratigraphy of the Permian was based on [[Ammonoidea|ammonoids]]; however, ammonoid localities are rare in Permian stratigraphic sections, and species characterise relatively long periods of time. All GSSPs for the Permian are based around the [[first appearance datum]] of specific species of [[conodont]], an enigmatic group of jawless [[chordate]]s with hard tooth-like oral elements. Conodonts are used as [[Biostratigraphy|index fossils]] for most of the Palaeozoic and the Triassic.<ref name="Lucas-2018">{{Cite journal|last1=Lucas|first1=Spencer G.|last2=Shen|first2=Shu-Zhong|date=2018|title=The Permian timescale: an introduction|journal=Geological Society, London, Special Publications|language=en|volume=450|issue=1|pages=1–19|doi=10.1144/SP450.15|bibcode=2018GSLSP.450....1L|issn=0305-8719|doi-access=free}}</ref>

=== Cisuralian ===
The Cisuralian Series is named after the strata exposed on the western slopes of the Ural Mountains in Russia and Kazakhstan. The name was proposed by J. B. Waterhouse in 1982 to comprise the Asselian, Sakmarian, and Artinskian stages. The Kungurian was later added to conform to the Russian "Lower Permian". [[Albert Auguste Cochon de Lapparent]] in 1900 had proposed the "Uralian Series", but the subsequent inconsistent usage of this term meant that it was later abandoned.<ref>{{cite book|last1=Gradstein|first1=Felix M.|url=https://books.google.com/books?id=rse4v1P-f9kC&pg=PA254|title=A geologic time scale 2004|last2=Ogg|first2=James G.|last3=Smith|first3=Alan G.|date=2004|publisher=Cambridge University Press|isbn=978-0-521-78673-7|page=250|access-date=2021-04-17|archive-date=2023-07-16|archive-url=https://web.archive.org/web/20230716091926/https://books.google.com/books?id=rse4v1P-f9kC&pg=PA254|url-status=live}}</ref>

The Asselian was named by the Russian stratigrapher V.E. Ruzhenchev in 1954, after the [[Assel River]] in the southern Ural Mountains. The GSSP for the base of the Asselian is located in the Aidaralash River valley near [[Aqtöbe]], Kazakhstan, which was ratified in 1996. The beginning of the stage is defined by the first appearance of ''[[Streptognathodus|Streptognathodus postfusus]].''<ref>Davydov, V.I., Glenister, B.F., Spinosa, C., Ritter, S.M., Chernykh, V.V., Wardlaw, B.R. & Snyder, W.S. 1998. [https://www.researchgate.net/publication/237222028_Proposal_of_Aidaralash_as_Global_Stratotype_Section_and_Point_GSSP_for_base_of_the_Permian_System Proposal of Aidaralash as Global Stratotype Section and Point (GSSP) for base of the Permian System] {{Webarchive|url=https://web.archive.org/web/20210416103303/https://www.researchgate.net/publication/237222028_Proposal_of_Aidaralash_as_Global_Stratotype_Section_and_Point_GSSP_for_base_of_the_Permian_System |date=2021-04-16 }}. Episodes, 21, 11–17.</ref>

The Sakmarian is named in reference to the [[Sakmara River]] in the southern Urals, and was coined by [[Alexander Karpinsky]] in 1874. The GSSP for the base of the Sakmarian is located at the Usolka section in the southern Urals, which was ratified in 2018. The GSSP is defined by the first appearance of ''[[Sweetognathus|Sweetognathus binodosus]]''.<ref>{{Cite journal|last1=Chernykh|first1=by Valery V.|last2=Chuvashov|first2=Boris I.|last3=Shen|first3=Shu-Zhong|last4=Henderson|first4=Charles M.|last5=Yuan|first5=Dong-Xun|last6=Stephenson|first6=and Michael H.|date=2020-12-01|title=The Global Stratotype Section and Point (GSSP) for the base- Sakmarian Stage (Cisuralian, Lower Permian)|journal=Episodes |language=en|volume=43|issue=4|pages=961–979|doi=10.18814/epiiugs/2020/020059|doi-access=free}}</ref>

The Artinskian was named after the city of [[Arti, Russia|Arti]] in [[Sverdlovsk Oblast]], Russia. It was named by Karpinsky in 1874. The Artinskian currently lacks a defined GSSP.<ref name="Cohen-2013" /> The proposed definition for the base of the Artinskian is the first appearance of ''Sweetognathus aff. S. whitei.<ref name="Lucas-2018" />''

The Kungurian takes its name after [[Kungur]], a city in Perm Krai. The stage was introduced by Alexandr Antonovich Stukenberg in 1890. The Kungurian currently lacks a defined GSSP.<ref name="Cohen-2013" /> Recent proposals have suggested the appearance of [[Neostreptognathodus|''Neostreptognathodus pnevi'']] as the lower boundary.<ref name="Lucas-2018" />

=== Guadalupian ===
The Guadalupian Series is named after the [[Guadalupe Mountains]] in Texas and New Mexico, where extensive marine sequences of this age are exposed. It was named by [[George Herbert Girty]] in 1902.<ref name="Glenister-1999">Glenister, B.F., Wardlaw, B.R. et al. 1999. [https://permian.stratigraphy.org/files/Roadian-Capitanian.pdf Proposal of Guadalupian and component Roadian, Wordian and Capitanian stages as international standards for the middle Permian series] {{Webarchive|url=https://web.archive.org/web/20210416232350/https://permian.stratigraphy.org/files/Roadian-Capitanian.pdf |date=2021-04-16 }}. ''Permophiles'', '''34''', 3–11.</ref>

The Roadian was named in 1968 in reference to the Road Canyon Member of the [[Word Formation]] in Texas.<ref name="Glenister-1999" /> The GSSP for the base of the Roadian is located 42.7m above the base of the [[Cutoff Formation]] in Stratotype Canyon, Guadalupe Mountains, Texas, and was ratified in 2001. The beginning of the stage is defined by the first appearance of [[Jinogondolella|''Jinogondolella nankingensis'']].<ref name="Lucas-2018" />

The Wordian was named in reference to the Word Formation by [[Johan August Udden]] in 1916, Glenister and Furnish in 1961 was the first publication to use it as a chronostratigraphic term as a substage of the Guadalupian Stage.<ref name="Glenister-1999" /> The GSSP for the base of the Wordian is located in Guadalupe Pass, Texas, within the sediments of the Getaway Limestone Member of the [[Cherry Canyon Formation]], which was ratified in 2001. The base of the Wordian is defined by the first appearance of the conodont ''Jinogondolella aserrata.''<ref name="Lucas-2018" />

The Capitanian is named after the Capitan Reef in the Guadalupe Mountains of Texas, named by [[George Burr Richardson]] in 1904, and first used in a chronostratigraphic sense by Glenister and Furnish in 1961 as a substage of the Guadalupian Stage.<ref name="Glenister-1999" /> The Capitanian was ratified as an international stage by the ICS in 2001. The GSSP for the base of the Capitanian is located at Nipple Hill in the southeast Guadalupe Mountains of Texas, and was ratified in 2001, the beginning of the stage is defined by the first appearance of ''Jinogondolella postserrata.<ref name="Lucas-2018" />''

=== Lopingian ===
The Lopingian was first introduced by [[Amadeus William Grabau]] in 1923 as the "Loping Series" after [[Leping]], [[Jiangxi]], China. Originally used as a lithostraphic unit, T.K. Huang in 1932 raised the Lopingian to a series, including all Permian deposits in South China that overlie the Maokou Limestone. In 1995, a vote by the Subcommission on Permian Stratigraphy of the ICS adopted the Lopingian as an international standard chronostratigraphic unit.''<ref name="Jin etal-2006">{{aut|Jin, Y.; Shen, S.; Henderson, C. M.; Wang, X.; Wang, W.; Wang, Y.; Cao, C. & Shang, Q.}}; '''2006''': [https://stratigraphy.org/gssps/files/wuchiapingian.pdf ''The Global Stratotype Section and Point (GSSP) for the boundary between the Capitanian and Wuchiapingian Stage (Permian)''] {{Webarchive|url=https://web.archive.org/web/20210828153020/https://stratigraphy.org/gssps/files/wuchiapingian.pdf |date=2021-08-28 }}, Episodes '''29(4)''', pp.&nbsp;253–262</ref>''

The Wuchiapinginan and Changhsingian were first introduced in 1962, by J. Z. Sheng as the "Wuchiaping Formation" and "Changhsing Formation" within the Lopingian series. The GSSP for the base of the Wuchiapingian is located at Penglaitan, [[Guangxi]], China and was ratified in 2004. The boundary is defined by the first appearance of [[Clarkina|''Clarkina postbitteri postbitteri'']]''<ref name="Jin etal-2006" />'' The Changhsingian was originally derived from the Changxing Limestone, a geological unit first named by the Grabau in 1923, ultimately deriving from [[Changxing County]], [[Zhejiang]] .The GSSP for the base of the Changhsingian is located 88&nbsp;cm above the base of the Changxing Limestone in the Meishan D section, Zhejiang, China and was ratified in 2005, the boundary is defined by the first appearance of ''Clarkina wangi.''<ref>{{Cite journal|last1=Jin|first1=Yugan|last2=Wang|first2=Yue|last3=Henderson|first3=Charles|last4=Wardlaw|first4=Bruce R.|last5=Shen|first5=Shuzhong|last6=Cao|first6=Changqun|date=2006-09-01|title=The Global Boundary Stratotype Section and Point (GSSP) for the base of Changhsingian Stage (Upper Permian)|journal=Episodes|language=en|volume=29|issue=3|pages=175–182|doi=10.18814/epiiugs/2006/v29i3/003|issn=0705-3797|doi-access=free}}</ref>

The GSSP for the base of the Triassic is located at the base of Bed 27c at the Meishan D section, and was ratified in 2001. The GSSP is defined by the first appearance of the conodont ''[[Hindeodus|Hindeodus parvus]]''.<ref>{{cite journal|last1=Hongfu|first1=Yin|last2=Kexin|first2=Zhang|last3=Jinnan|first3=Tong|last4=Zunyi|first4=Yang|last5=Shunbao|first5=Wu|date=June 2001|title=The Global Stratotype Section and Point (GSSP) of the Permian-Triassic Boundary|url=https://stratigraphy.org/gssps/files/induan.pdf|journal=Episodes|volume=24|issue=2|pages=102–114|doi=10.18814/epiiugs/2001/v24i2/004|access-date=8 December 2020|doi-access=free|archive-date=28 August 2021|archive-url=https://web.archive.org/web/20210828153134/https://stratigraphy.org/gssps/files/induan.pdf|url-status=live}}</ref>

=== Regional stages ===
The Russian Tatarian Stage includes the Lopingian, Capitanian and part of the Wordian, while the underlying Kazanian includes the rest of the Wordian as well as the Roadian.<ref name="Olroyd-2017" /> 

In North America, the Permian is divided into the Wolfcampian (which includes the Nealian and the Lenoxian stages); the Leonardian (Hessian and Cathedralian stages); the Guadalupian; and the Ochoan, corresponding to the Lopingian.<ref>{{cite book |last1=Ross |first1=C. A. |last2=Ross |first2=June R. P. |title=The Permian of Northern Pangea |chapter=Permian Sequence Stratigraphy |date=1995 |pages=98–123 |doi=10.1007/978-3-642-78593-1_7|isbn=978-3-642-78595-5 }}</ref><ref>{{cite web |title=Permian: Stratigraphy |url=https://ucmp.berkeley.edu/permian/permstrat.html |website=UC Museum of Paleontology |publisher=University of California Berkeley |access-date=17 June 2021 |archive-date=5 February 2022 |archive-url=https://web.archive.org/web/20220205180600/https://ucmp.berkeley.edu/permian/permstrat.html |url-status=live }}</ref>

The [[New Zealand geologic time scale]] divides the Permian into three epochs, Pre-Telfordian (undivided), D'Urville (divided into the Makarewan, Waiitian, and Puruhauan stages), and Aparima (Flettian, Barrettian, Mangapirian, and Telfordian stages). The Pre-Telfordian epoch corresponds approximately to the Asselian, Sakmarian, and Artinskian stages; the D'Urville epoch is roughly contemporary with the Kungurian stage and Guadalupian epoch; and the Aparima epoch is closely contemporary with the Lopingian epoch.<ref>{{cite journal|last1=Cooper |first1= R. A. |year= 2004 |title=The New Zealand geological timescale |journal= Institute of Geological and. Nuclear Sciences Monograph |volume=22 |pages= 1–284 |url=https://shop.gns.cri.nz/mon22/ }}</ref>