In the geologic timescale, the Wordian is an age or stage of the Permian. It is the middle of three subdivisions of the Guadalupian Epoch or Series. The Wordian lasted between 266.9 and 264.28 million years ago (Ma). It was preceded by the Roadian and followed by the Capitanian.[3]
| Wordian | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chronology | |||||||||||||
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| 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 Jinogondolella aserrata | ||||||||||||
| Lower boundary GSSP | Guadalupe Pass, Guadalupe Mountains, Texas, USA 31°51′57″N 104°49′58″W / 31.8658°N 104.8328°W | ||||||||||||
| Lower GSSP ratified | 2001[2] | ||||||||||||
| Upper boundary definition | FAD of the Conodont Jinogondolella postserrata | ||||||||||||
| Upper boundary GSSP | Nipple Hill, Guadalupe Mountains, Texas, USA 31°54′33″N 104°47′21″W / 31.9091°N 104.7892°W | ||||||||||||
| Upper GSSP ratified | 2001[2] | ||||||||||||
Stratigraphy
editThe Wordian Stage was introduced into scientific literature by Johan August Udden in 1916 and was named after the Word Formation of the North American Permian Basin. The Wordian was first used as a stratigraphic subdivision of the Guadalupian in 1961,[4] when both names were still only used regionally in the southern US. The stage was added to the internationally used ISC timescale in 2001.[5]
The base of the Wordian Stage is defined as the place in the stratigraphic record where fossils of conodont species Jinogondolella aserrata first appear. The global reference profile for this stratigraphic boundary is located at Getaway Ledge in the Guadalupe Mountains of Texas.
The top of the Wordian (the base of the Capitanian Stage) is defined as the place in the stratigraphic record where the conodont species Jinogondolella postserrata first appears.
The Wordian stage was part of the time in which the Zechstein was deposited in Europe.
Biostratigraphy
editThe Wordian spans the entire conodont biozone of Jinogondolella aserrata. It contains two fusulinid biozones:
- Zone of Afganella tereshkovae
- Zone of Neoschwagerina tenuis
Wordian life
editOlson’s Extinction, a worldwide loss of terrestrial vertebrate life occurred during the Early Guadalupian (Roadian, Wordian).[6]
Notable formations
edit- Gnishik Formation (Armenia, Azerbaidjan, Iran)
- Word Formation (Texas, United States)
References
edit- ^ "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. September 2023. Retrieved November 10, 2024.
- ^ a b "GSSP for Roadian Stage". International Commission on Stratigraphy. Retrieved 13 December 2020.
- ^ Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press
- ^ Glenister, B.F. & Furnish, W.M.; 1961: The Permian ammonoids of Australia, Journal of Paleontology 35(4), pp 673–736.
- ^ Glenister, B.F.; Wardlaw, B.R.; Lambert, L.L.; Spinosa, C.; Bowring, S.A.; Erwin, D.H.; Menning, M. & Wilde, G.L.; 1999: Proposal of Guadalupian and Component Roadian, Wordian and Capitanian Stages as International Standards for the Middle Permian Series, Permophiles 34: pp 3–11.
- ^ Sahney, S. & Benton, M.J. (2008). "Recovery from the most profound mass extinction of all time". Proceedings of the Royal Society B: Biological Sciences. 275 (1636): 759–65. doi:10.1098/rspb.2007.1370. PMC 2596898. PMID 18198148.
Literature
editExternal links
edit- GeoWhen Database - Wordian
- Upper Paleozoic stratigraphic chart at the website of the subcommission for stratigraphic information of the ICS