Barremian Explained

Barremian
Color:Barremian
Time Start:125.77
Time Start Prefix:~
Time End:121.4
Time End Prefix:~
Image Outcrop:StratotypeBarremienA.JPG
Caption Outcrop:Barremian sedimentary rock layers, France
Timeline:Cretaceous
Name Formality:Formal
Celestial Body:earth
Usage:Global (ICS)
Timescales Used:ICS Time Scale
Chrono Unit:Age
Strat Unit:Stage
Timespan Formality:Formal
Lower Boundary Def:Not formally defined
Lower Def Candidates:FAD of the Spitidiscus hugii-Spitidiscus vandeckii Ammonite group
Lower Gssp Candidates:Río Argos, Caravaca de la Cruz, Murcia Province, Spain
Upper Boundary Def:Not formally defined
Upper Def Candidates:
Upper Gssp Candidates: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[1] (Historically, this stage was placed at 129.4 million to approximately 125 million years ago[2]) 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.[3]

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.

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 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.

Subdivision

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:

References

Literature

(2004): A Geologic Time Scale 2004, Cambridge University Press.

External links

Notes and References

  1. Cohen, K.M., Finney, S.C., Gibbard, P.L. & Fan, J.-X. (2013; updated) The ICS International Chronostratigraphic Chart. Episodes 36: 199-204.
  2. Web site: March 2020 . ICS-Geological Timescale . 29 June 2023 . stratigraphy.or.
  3. See Gradstein et al. (2004) or the online geowhen database (link below)