Norian
ColorNorian
Time start227.3
Time end205.7
TimelineTriassic
Name formalityFormal
Celestial bodyearth
UsageGlobal (ICS)
Timescales usedICS Time Scale
Chrono unitAge
Strat unitStage
Timespan formalityFormal
Lower boundary defNot formally defined[1]
Lower def candidatesBase of Stikinoceras kerri ammonoid zone and near FAD of Metapolygnathus echinatus within the M. communisti Conodont zones[1]
Lower gssp candidates
Upper boundary defNot formally defined[1]
Upper def candidates
Upper gssp candidates

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 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.[3]

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:

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.[4]

Notable formations

References

Notes

  1. ^ "Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Retrieved 23 December 2020.
  2. ^ 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
  3. ^ "ICS - Chart/Time Scale". Archived 2025-01-01 at the Wayback Machine. Retrieved 2025-01-14.
  4. ^ Martz, J. W. & Parker, W. G. (2017-01-01), "Revised Formulation of the Late Triassic Land Vertebrate "Faunachrons" of Western North America: Recommendations for Codifying Nascent Systems of Vertebrate Biochronology", Terrestrial Depositional Systems, Zeigler, Kate E. (ed.), Elsevier, pp. 39–125, ISBN 978-0-12-803243-5, retrieved 2022-08-28

Literature

  • 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.
    2004
    A Geologic Time Scale 2004, Cambridge University Press.
    2004
    Mammals from the Age of Dinosaurs, Columbia University Press.
    2008
    Lithostratigraphy, chemostratigraphy, and vertebrate biostratigraphy of the Dockum Group (Upper Triassic), of southern Garza County, West Texas, Doctoral Dissertation, Texas Tech.