Cenomanian

Coordinates: 44°23′33″N 5°30′43″E / 44.39250°N 5.51194°E / 44.39250; 5.51194
Source: Wikipedia, the free encyclopedia.
Cenomanian
100.5 – 93.9 Ma
Chronology

The Cenomanian is, in the

Upper Cretaceous Series.[4] An age is a unit of geochronology; it is a unit of time; the stage is a unit in the stratigraphic column
deposited during the corresponding age. Both age and stage bear the same name.

As a unit of geologic time measure, the Cenomanian Age spans the time between[5] 100.5 and 93.9 million years ago (Mya). In the geologic timescale, it is preceded by the Albian and is followed by the Turonian. The Upper Cenomanian starts around at 95 Mya.[citation needed]

The Cenomanian is coeval with the Woodbinian of the regional timescale of the Gulf of Mexico and the early part of the Eaglefordian of the regional timescale of the East Coast of the United States.

At the end of the Cenomanian, an anoxic event took place, called the Cenomanian-Turonian boundary event or the "Bonarelli event", that is associated with a minor extinction event for marine species.

Myanmar amber in which it was discovered.[6]

Stratigraphic definitions

The Cenomanian was introduced in scientific literature by French

palaeontologist Alcide d'Orbigny in 1847. Its name comes from the Neo-Latin name of the French city of Le Mans (département Sarthe
), Cenomanum. The base of the Cenomanian Stage (which is also the base of the Upper Cretaceous Series) is placed at the first appearance of
Marnes Bleues Formation.[7]

The top of the Cenomanian (the base of the Turonian) is at the first appearance of

ammonite species Watinoceras devonense
.

Important

index fossils for the Cenomanian are the ammonites Calycoceras naviculare, Acanthoceras rhotomagense, and Mantelliceras mantelli
.

Sequence stratigraphy and palaeoclimatology

The late Cenomanian represents the highest

Tectonic mountain building was minimal and most continents were isolated by large stretches of water. Without highlands to break winds, the climate would have been windy and waves large, adding to the weathering and fast rate of sediment deposition.[citation needed
]

References

  1. ^ International Commission on Stratigraphy. "ICS - Chart/Time Scale". www.stratigraphy.org.
  2. doi:10.18814/epiiugs/2004/v27i1/003
    . Retrieved 13 December 2020.
  3. doi:10.18814/epiiugs/2005/v28i2/003
    .
  4. ^ See for a detailed geologic timescale Gradstein et al. (2004)
  5. ^ "International Stratigraphic Chart v2021/05". Archived from the original on 2021-06-05. Retrieved 2021-07-29.
  6. doi:10.1016/j.cretres.2019.03.005.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  7. ^ The GSSP for the Cenomanian was established by Kennedy et al. (2004)

Further reading

  • Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
  • Kennedy, W.J.; Gale, A.S.; Lees, J.A. & Caron, M.; 2004: The Global Boundary Stratotype Section and Point (GSSP) for the base of the Cenomanian Stage, Mont Risou, Hautes-Alpes, France, Episodes 27, pp. 21–32.

External links

44°23′33″N 5°30′43″E / 44.39250°N 5.51194°E / 44.39250; 5.51194

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