Norian

The Norian is a division of the Triassic Period. It has the rank of an age (geochronology) or stage (chronostratigraphy). It lasted from ~227 to 208.5 million years ago.^[8] It was preceded by the Carnian and succeeded by the Rhaetian.^[9]

Norian
~227 – ~208.5 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Chronology
−255 — – −250 — – −245 — – −240 — – −235 — – −230 — – −225 — – −220 — – −215 — – −210 — – −205 — – −200 — Pz Mesozoic P Triassic J Lopingian Early Middle Late E J Changhsing. Olenekian Induan Anisian Ladinian Carnian Norian Rhaetian Hettangian         ← Permian-Triassic extinction event ← Smithian–Spathian boundary event[1] ← Carnian pluvial episode ← Full recovery of woody trees[2] ← Coals return[3] ← Scleractinian corals & calcified sponges[4] ← Triassic–Jurassic extinction event ← Manicouagan impact Subdivision of the Triassic according to the ICS, as of 2023.[5] 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	Not formally defined[6]
Lower boundary definition candidates	Base of Stikinoceras kerri ammonoid zone and near FAD of Metapolygnathus echinatus within the M. communisti Conodont zones[6]
Lower boundary GSSP candidate section(s)	Black Bear Ridge, British Columbia, Canada[6] Pizzo Mondello, Sicily, Italy[6]
Upper boundary definition	Not formally defined[6]
Upper boundary definition candidates	FAD of the Conodont Misikella posthernsteini Near FAD of the Ammonite genus Cochloceras[6] Near FAD of the Conodont Epigondolella mosheri[6] Near FAD of the Radiolarian Proparvicingula moniliformis[6]
Upper boundary GSSP candidate section(s)	Steinbergkogel, Austria[6] Pignola-Abriola, Italy[7] Turkey[6] British Columbia, Canada[6]

Stratigraphic definitions

Cast of a tridactyl footprint of a theropod dinosaur from the Norian of the Czech Republic.

The Norian was named after the Noric Alps in Austria. The stage was introduced into scientific literature by Austrian geologist Edmund Mojsisovics von Mojsvar in 1869.

The Norian Stage begins at the base of the ammonite biozones of Klamathites macrolobatus and Stikinoceras kerri, and at the base of the conodont biozones of Metapolygnathus communisti and Metapolygnathus primitius. A global reference profile for the base (a GSSP) had in 2009 not yet been appointed.

The top of the Norian (the base of the Rhaetian) is at the first appearance of ammonite species Cochloceras amoenum. The base of the Rheatian is also close to the first appearance of conodont species Misikella spp. and Epigondolella mosheri and the radiolarid species Proparvicingula moniliformis.

In the Tethys domain, the Norian Stage contains six ammonite biozones:

• zone of Halorites macer
• zone of Himavatites hogarti
• zone of Cyrtopleurites bicrenatus
• zone of Juvavites magnus
• zone of Malayites paulckei
• zone of Guembelites jandianus

Subages

The Norian is divided into three global subages or substages:

• Lacian (lower Norian)
• Alaunian (middle Norian)
• Sevatian (upper Norian)

Many older studies considered the Rhaetian to be the uppermost substage of the Norian, though it has subsequently been raised to its own stage.

The Revueltian land-vertebrate faunachron corresponds to part of the Norian.^[10]

Notable formations

• Calcare di Zorzino (Italy)
• Caturrita Formation (Rio Grande do Sul, Brazil)
• Chinle Formation (SW USA)
• Cow Branch Formation (North Carolina and Virginia, USA)
• Dolomia di Forni (Italy)
• Los Colorados Formation (Argentina)
• Stubensandstein (Germany)
• Trossingen Formation (Norian – Rhaetian) (Switzerland and Germany)

References

Notes

1. Widmann, Philipp; Bucher, Hugo; Leu, Marc; et al. (2020). "Dynamics of the Largest Carbon Isotope Excursion During the Early Triassic Biotic Recovery". Frontiers in Earth Science. 8 (196): 196. Bibcode:2020FrEaS...8..196W. doi:10.3389/feart.2020.00196.
2. McElwain, J. C.; Punyasena, S. W. (2007). "Mass extinction events and the plant fossil record". Trends in Ecology & Evolution. 22 (10): 548–557. doi:10.1016/j.tree.2007.09.003. PMID 17919771.
3. Retallack, G. J.; Veevers, J.; Morante, R. (1996). "Global coal gap between Permian–Triassic extinctions and middle Triassic recovery of peat forming plants". GSA Bulletin. 108 (2): 195–207. Bibcode:1996GSAB..108..195R. doi:10.1130/0016-7606(1996)108<0195:GCGBPT>2.3.CO;2. Retrieved 2007-09-29.
4. Payne, J. L.; Lehrmann, D. J.; Wei, J.; Orchard, M. J.; Schrag, D. P.; Knoll, A. H. (2004). "Large Perturbations of the Carbon Cycle During Recovery from the End-Permian Extinction". Science. 305 (5683): 506–9. Bibcode:2004Sci...305..506P. doi:10.1126/science.1097023. PMID 15273391. S2CID 35498132.
5. "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. September 2023. Retrieved December 16, 2024.
6. "Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Retrieved 23 December 2020.
7. Rigo, Manuel; Bertinelli, Angela; Concheri, Giuseppe; Gattolin, Giovanni; Godfrey, Linda; Katz, Miriam E.; Maron, Matteo; Mietto, Paolo; Muttoni, Giovanni; Sprovieri, Mario; Stellin, Fabio; Mariachiara, Zaffani (2016). "The Pignola-Abriola section (southern Apennines, Italy): a new GSSP candidate for the base of the Rhaetian Stage". Lethaia. 49 (3): 287–306. Bibcode:2016Letha..49..287R. doi:10.1111/let.12145. hdl:11577/3157425. ISSN 1502-3931.{{cite journal}}: CS1 maint: multiple names: authors list (link)
8. According to Gradstein et al. (2004). Brack et al. (2005) give 226 to 207 million years
9. See for a detailed geologic timescale Gradstein et al. (2004)
10. Spielmann, J.A.; Lucas, S.G.; Hunt, A.P. (2013). "The first Norian (Revueltian) rhynchosaur: Bull Canyon Formation, New Mexico, USA" (PDF). New Mexico Museum of Natural History and Science Bulletin. 61: 562. Retrieved 17 November 2021.

Literature

• Brack, P.; Rieber, H.; Nicora, A. & Mundil, R.; 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), pp. 233–244.
• Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
• Kielan-Jaworowska, Z.; Cifelli, R. L.; Luo, Zhe-Xi; 2004: Mammals from the Age of Dinosaurs, Columbia University Press.
• Martz, J.W.; 2008: Lithostratigraphy, chemostratigraphy, and vertebrate biostratigraphy of the Dockum Group (Upper Triassic), of southern Garza County, West Texas, Doctoral Dissertation, Texas Tech.

External links

• GeoWhen Database - Norian
• Upper Triassic timescale, at the website of the subcommission for stratigraphic information of the ICS
• Norges Network of offshore records of geology and stratigraphy: Stratigraphic charts for the Triassic, and