Olenekian
Olenekian | |
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Upper boundary definition | Not formally defined |
Upper boundary definition candidates |
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Upper boundary GSSP candidate section(s) |
In the
The Olenekian saw the deposition of a large part of the Buntsandstein in Europe. The Olenekian is roughly coeval with the regional Yongningzhenian Stage used in China.
Stratigraphic definitions
The Olenekian Stage was introduced into scientific literature by Russian stratigraphers in 1956.
The base of the Olenekian is at the lowest occurrence of the
In the 1960s, English paleontologist Edward T. Tozer (sometimes collaborating with American geologist Norman J. Silberling) crafted Triassic timescales based on North American ammonoid zones, further refining it in the following decades. Tozer's nomenclature was largely derived from Mojsisovics's work, who coined most of the Triassic stages and substages, but he redefined them using North American sites. He recommended the Lower Triassic series be divided into the Griesbachian, Dienerian, Smithian, and Spathian. The latter two roughly correspond with the Olenekian. Tozer's timescale became popular in the Americas.[11] He named the Smithian after Smith Creek on Ellesmere Island, Canada (the creek itself is named after geologist J. P. Smith). The Smithian is defined by the Arctoceras bloomstrandi ammonoid zone (contains Euflemingites romunderi and Juvenites crassus) and the overlying Meekoceras gracilitatis and Wasatchites tardus subzones. He named the Spathian after Spath Creek on Ellesmere Island (this creek is named after geologist L. F. Spath), and defined it by the Procolumbites subrobustus ammonoid zone.[8]
Olenekian life
Life was still recovering from the severe
In the oceans,
Olenekian
Marine
The first marine reptiles appeared during the Olenekian.
An example of an exceptionally diverse Early Triassic assemblage is the
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Life restoration of Pleuromeia, a genus of lycophyte that was globally abundant during the Olenekinian
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Skull of theray-finned fish Birgeriaamericana
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Skull of thetemnospondyl amphibian Trematosaurusbrauni
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Skull of thearchosauriform reptile Erythrosuchusafricanus
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Marine ichthyosauromorph reptile Chaohusaurus
Smithian–Spathian boundary event
An important extinction event occurred during the Olenekian age of the Early Triassic, near the Smithian and Spathian subage boundary. The main victims of this Smithian–Spathian boundary event, often called the Smithian–Spathian extinction,
The
The Smithian–Spathian boundary extinction was linked to late eruptions of the
In the ocean, many large and mobile species moved away from the
There is evidence that life had recovered rapidly, at least locally. This is indicated by sites that show exceptionally high biodiversity (e.g. the earliest Spathian
Notable formations
- Middle Buntsandstein(Germany)
- Cynognathus Assemblage Zone / Burgersdorp Formation (subzones A-B)* (South Africa)
- Lower Ermaying Formation* (Shaanxi and Shanxi, China)
- Upper Fremouw Formation* (Antarctica)
- Jialingjiang Formation (South China)
- Moenkopi Formation (Torrey and Wutapki members)* (SW USA)
- Nanlinghu Formation (Anhui, China)
- Rybinskian Gorizont* (European Russia)
- Sanga do Cabral Formation* (Rio Grande do Sul, Brazil)
- Sludkian Gorizont* (European Russia)
- Sulphur Mountain Formation (British Columbia, Canada)
- Thaynes Group/Limestone (western USA)
- Ustmylian Gorizont* (European Russia)
- Virgin Formation (Utah, USA)
- Vikinghøgda Formation (Lusitaniadalen and Vendomdalen members) (Svalbard, Norway)
- Yarenskian Gorizont* (European Russia)
* Tentatively assigned to the Olenekian; age estimated primarily via terrestrial tetrapod biostratigraphy (see Triassic land vertebrate faunachrons)
References
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- ^ "Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Retrieved 23 December 2020.
- ^ According to Gradstein (2004). Brack et al. (2005) give 251 to 248 Ma
- ^ doi:10.4095/100985.
- ^ See for a detailed geologic timescale Gradstein et al. (2004)
- ^ Kiparisova & Popov (1956)
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- ^ Nielsen, Eigil (1936). "Some few preliminary remarks on Triassic fishes from East Greenland". Meddelelser om Grønland. 112 (3): 1–55.
- ^ Beltan, Laurence (1996). "Overview of systematics, paleobiology, and paleoecology of Triassic fishes of northwestern Madagascar". In G. Arratia; G. Viohl (eds.). Mesozoic Fishes—Systematics and Paleoecology. München: Dr. Friedrich Pfeil. pp. 479–500.
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- ^ a b Stensiö, E. (1921). Triassic fishes from Spitzbergen 1. Wien: Adolf Holzhausen. pp. xxviii+307.
- ^ Stensiö, E. (1925). "Triassic fishes from Spitzbergen 2". Kungliga Svenska Vetenskapsakademiens Handlingar. 3: 1–261.
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Extinctions with and at the close of the Triassic
- ISSN 0921-8181. Retrieved 3 January 2024 – via Elsevier Science Direct.
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- ^ Marshall, Michael (18 October 2012). "Roasting Triassic heat exterminated tropical life". New Scientist.
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Further reading
- Brack, Peter; Rieber, Hans; Nicora, Alda; Mundil, Roland (1 December 2005). "The Global boundary Stratotype Section and Point (GSSP) of the Ladinian Stage (Middle Triassic) at Bagolino (Southern Alps, Northern Italy) and its implications for the Triassic time scale". Episodes. 28 (4): 233–244. .
- Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
- Kiparisova, L.D. & Popov, J.N.; 1956: Расчленение нижнего отдела триасовой системы на ярусы (Subdivision of the lower series of the Triassic System into stages), Doklady Akademii Nauk SSSR109(4), pp 842–845 (in Russian).
External links
- GeoWhen Database - Olenekian
- Lower Triassic timescale at the website of the subcommission for stratigraphic information of the ICS
- Lower Triassic timescale at the website of Norges Network of offshore records of geology and stratigraphy.