The Barremian is an

age Age or AGE may refer to: Time and its effects * Age, the amount of time someone or something has been alive or has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming olde ...

in the

geologic timescale The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geoch ...

(or a

chronostratigraphic Chronostratigraphy is the branch of stratigraphy that studies the ages of rock strata in relation to time. The ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geological ...

stage) between 129.4 ± 1.5 Ma (

million years ago The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). ...

) and 121.4 ± 1.0 Ma). It is a subdivision of the

Early Cretaceous The Early Cretaceous (geochronological name) or the Lower Cretaceous ( chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pr ...

Epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...

(or

Lower Cretaceous Lower may refer to: *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Gloucestershire, England See also *Nizhny Nizhny (russian: Ни́жний; masculine), Nizhnyaya (; feminine), or Nizhneye (russian: Ни́� ...

Series). It is preceded by the

Hauterivian The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous Epoch or a stage in the Lower Cretaceous Series. It spans the time between 132.9 ± 2 Ma and 129.4 ± 1.5 Ma (million years ago). The Hauterivian is preceded by t ...

and followed by the

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ag ...

Stage.See Gradstein ''et al.'' (2004) or the online geowhen database (link below)

Stratigraphic definitions

The original

type locality Type locality may refer to: * Type locality (biology) * Type locality (geology) See also * Local (disambiguation) * Locality (disambiguation) {{disambiguation ...

for the Barremian Stage is in the vicinity of the village of

Barrême Barrême (; oc, Barrema) is a commune in the southeastern French department of Alpes-de-Haute-Provence. The inhabitants of this commune are known as ''Barrêmois'' or ''Barrêmoises''. Geography Barrême is located at an altitude of 722 m som ...

Alpes-de-Haute-Provence Alpes-de-Haute-Provence or sometimes abbreviated as AHP (; oc, Aups d'Auta Provença; ) is a department in the Provence-Alpes-Côte d'Azur region of France, bordering Alpes-Maritimes and Italy to the east, Var to the south, Vaucluse to the wes ...

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan ar ...

Henri Coquand Henri Coquand (1813, in Aix-en-Provence – 1881, in Marseille) was a French geologist and paleontologist. In 1841 he obtained his doctorate in sciences in Paris, and later served as a professor of geology at the University of Besançon, Poitie ...

defined the stage and named it in 1873. The base of the Barremian is determined by the first appearance of the

ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttle ...

s ''

Spitidiscus hugii ''Spitidiscus'' is a genus of ammonites placed in the family Holcodiscidae. with and (1996), ''Mollusca 4 Revised , Cretaceous Ammonoidea'', vol. 4, in ''Treatise on Invertebrate Paleontology'', Part L (Roger L. Kaesler et el. eds.), Boulde ...

'' and ''Spitidiscus vandeckii''. The end of the Barremian is determined by the

geomagnetic reversal A geomagnetic reversal is a change in a planet's magnetic field such that the positions of magnetic north and magnetic south are interchanged (not to be confused with geographic north and geographic south). The Earth's field has alternated be ...

at the start of the M0r

chronozone A chronozone or chron is a unit in chronostratigraphy, defined by events such as geomagnetic reversals (magnetozones), or based on the presence of specific fossils (biozone or biochronozone). According to the International Commission on Stra ...

, which is biologically near the first appearance of the ammonite '' Paradeshayesites oglanlensis''.

Regional equivalents

The Barremian falls in the

Gallic epoch The Gallic epoch is an obsolete epoch of the Mesozoic Era's Cretaceous, the latter being a geologic period and system that spans 79 million years from the end of the Jurassic Period million years ago (mya) to the beginning of the Paleogene Per ...

, a subdivision of the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

that is no longer used by the

ICS ICS may refer to: Computing * Image Cytometry Standard, a digital multidimensional image file format used in life sciences microscopy * Industrial control system, computer systems and networks used to control industrial plants and infrastructu ...

. It overlaps the lower part of the Urgonian 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 New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 List of islands of New Zealand, smaller islands. It is the ...

, 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

biozone In biostratigraphy, biostratigraphic units or biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa, as opposed to a lithostratigraphic unit which is defined by the lithological properties ...

s: * 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

Literature

* (1907): Le Barrémien supérieur à faciès Urgonien de Brouzet-lès-Alais (Gard). ''Mémoires de la Société Géologique de France, Paléontologie'' 15(37): 5-42. *; (2004): A Geologic Time Scale 2004,

Cambridge University Press Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by Henry VIII of England, King Henry VIII in 1534, it is the oldest university press in the world. It is also the King's Printer. Cambr ...

. * (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.

External links

GeoWhen Database - BarremianMid-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 {{Cretaceous Footer *04 Geological ages Cretaceous geochronology