Norian
Template:Short description Template:Infobox geologic timespan
The Norian is a division of the Triassic Period. It has the rank of an age (geochronology) or stage (chronostratigraphy). It lasted from 227.3 to Expression error: Unexpected round operator million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.[1]
Stratigraphic definitions
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 (LVF) corresponds to part of the Norian (215–207 Ma), and it is probable that the Otischalkian and Adamanian LVFs (227–215 Ma) are also early-middle Norian in age.[2]
Notable formations
- Calcare di Zorzino (Italy)
- Caturrita Formation (Rio Grande do Sul, Brazil)
- Chinle Formation (Arizona and New Mexico, USA)
- Cow Branch Formation (North Carolina and Virginia, USA)
- Dockum Group (Carnian – Norian) (Texas and New Mexico, USA)
- Dolomia di Forni (Italy)
- Ischigualasto Formation (Carnian – Norian) (Argentina)
- Los Colorados Formation (Argentina)
- Stubensandstein (Germany)
- Trossingen Formation (Norian – Rhaetian) (Switzerland and Germany)
References
Notes
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- ^ Page Module:Citation/CS1/styles.css has no content."ICS - Chart/Time Scale" (PDF). Archived from the original (PDF) on 2025-01-01. Retrieved 2025-01-14.
- ^ Page Module:Citation/CS1/styles.css has no content.Martz, J. W.; Parker, W. G. (2017-01-01), Zeigler, Kate E.; Parker, William G. (eds.), "Revised Formulation of the Late Triassic Land Vertebrate "Faunachrons" of Western North America: Recommendations for Codifying Nascent Systems of Vertebrate Biochronology", Terrestrial Depositional Systems, Elsevier, pp. 39–125, ISBN 978-0-12-803243-5, retrieved 2022-08-28
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Literature
- Page Template:Smallcaps/styles.css has no content.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.
- Page Template:Smallcaps/styles.css has no content.Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
- Page Template:Smallcaps/styles.css has no content.Kielan-Jaworowska, Z.; Cifelli, R. L.; Luo, Zhe-Xi; 2004: Mammals from the Age of Dinosaurs, Columbia University Press.
- Page Template:Smallcaps/styles.css has no content.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, [1] and [2]
