Barremian

Barremian
Barremian
~125.77 – ~121.4 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
	Barremian sedimentary rock layers, France
Chronology
←	K-Pg mass; extinction
	Subdivision of the Cretaceous according to the ICS, as of 2023.; 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
Lower boundary definition candidates	FAD of the Spitidiscus hugii-Spitidiscus vandeckii Ammonite group
Lower boundary GSSP candidate section(s)	Río Argos, Caravaca de la Cruz, Murcia Province, Spain
Upper boundary definition	Not formally defined
Upper boundary definition candidates	Base of magnetic polarity chronozone M0r.; Near FAD of the Ammonite Paradeshayesites oglanlensis;
Upper boundary GSSP candidate section(s)	Gorgo a Cerbara, Piobbico, Central Apennines, Italy

The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 125.77 Ma (million years ago) and 121.4 ± 1.0 Ma^[2] (Historically, this stage was placed at 129.4 million to approximately 125 million years ago^[3]) It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded by the Hauterivian and followed by the Aptian Stage.^[4]

Stratigraphic definitions

The original type locality for the Barremian Stage is in the vicinity of the village of Barrême, Alpes-de-Haute-Provence, France. Henri Coquand defined the stage and named it in 1873.

The base of the Barremian is determined by the first appearance of the ammonites Spitidiscus hugii and Spitidiscus vandeckii. The end of the Barremian is determined by the geomagnetic reversal at the start of the M0r chronozone, which is biologically near the first appearance of the ammonite Paradeshayesites oglanlensis.^{[citation needed]}

Regional equivalents

The Barremian falls in the Gallic epoch, a subdivision of the Cretaceous that is no longer used by the ICS. It overlaps the lower part of the Urgonian [pl] stage, which is sometimes used in western European stratigraphy. In North America, the late Coahulian and the early Comanchean correspond to the Barremian. In New Zealand, it falls within the Mokoiwian, and in Japan it corresponds to the late Aritan.^[4]

Subdivision^{[citation needed]}

The Barremian is often subdivided into two substages or subages, Lower/Early and Upper/Late Barremian.

In the Tethys domain, the Barremian stage contains eleven ammonite biozones:

zone of Pseudocrioceras waagenoides
zone of Colchidites sarasini
zone of Imerites giraudi
zone of Hemihoplites feraudianus
zone of Gerhardtia sertousi
zone of Ancyloceras vandenheckii
zone of Coronites darsi
zone of Kotetishvilia compressissima
zone of Nicklesia pulchella
zone of Nicklesia nicklesi
zone of Spitidiscus hugii

References

Notes

^ International Commission on Stratigraphy. "ICS - Chart/Time Scale". www.stratigraphy.org.
^ Cohen, K.M., Finney, S.C., Gibbard, P.L. & Fan, J.-X. (2023; updated) The ICS International Chronostratigraphic Chart. Episodes 36: 199-204.
^ "ICS-Geological Timescale" (PDF). stratigraphy.or. March 2020. Retrieved 29 June 2023.
^ ^a ^b See Gradstein et al. (2004) or the online geowhen database (link below)

Literature

Cossmann, M. & Pelat, E. (1907): Le Barrémien supérieur à faciès Urgonien de Brouzet-lès-Alais (Gard). Mémoires de la Société Géologique de France, Paléontologie 15(37): 5-42. (in French)
Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; (2004): A Geologic Time Scale 2004, Cambridge University Press.
Guzhikov, A.Yu. & Baraboshkin, E.J. (2006): Assessment of diachronism of biostratigraphic boundaries by magnetochronological calibration of zonal scales for the Lower Cretaceous of the Tethyan and Boreal belts. Doklady Earth Sciences 409(6): 843-846. doi:10.1134/S1028334X06060018

External links

GeoWhen Database - Barremian
Mid-Cretaceous timescale, at the website of the subcommission for stratigraphic information of the ICS
Stratigraphic chart of the Lower Cretaceous, at the website of Norges Network of offshore records of geology and stratigraphy