Valanginian
{{short description|Second age of the early Cretaceous}}
{{Infobox geologic timespan
| name = Valanginian
| color = Valanginian
| time_start = 137.05
| time_start_uncertainty = 0.2
| time_end = 132.6
| time_end_uncertainty = 0.6
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| timeline = Cretaceous
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| name_formality = Formal
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| celestial_body = earth
| usage = Global (ICS)
| timescales_used = ICS Time Scale
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| chrono_unit = Age
| strat_unit = Stage
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| timespan_formality = Formal
| lower_boundary_def = Not formally defined
| lower_def_candidates = FAD of the Calpionellid Calpionellites darderi
| lower_gssp_candidates =
| upper_boundary_def = FAD of the Ammonite genus Acanthodiscus
| upper_gssp_location = La Charce, Drôme, France
| upper_gssp_coords = {{Coor|44.4694|N|5.4437|E|display=inline}}
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}}{{Update|date=May 2025}}
In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 137.05 ± 0.2 Ma and 132.6 ± 0.2 Ma (million years ago).Cohen, K.M., Finney, S.C., Gibbard, P.L. & Fan, J.-X. (2013; updated) [https://stratigraphy.org/ICSchart/ChronostratChart2024-12.pdf The ICS International Chronostratigraphic Chart]. Episodes 36: 199–204. The Valanginian Stage succeeds the Berriasian Stage of the Lower Cretaceous and precedes the Hauterivian Stage of the Lower Cretaceous.See Gradstein et al. (2004) for a detailed geologic timescale
Stratigraphic definitions
The Valanginian was first described and named by Édouard Desor in 1853. It is named after Valangin, a small town north of Neuchâtel in the Jura Mountains of Switzerland.
The base of the Valanginian is at the first appearance of calpionellid species Calpionellites darderi in the stratigraphic column. A global reference section (a GSSP) had in 2009 not yet been appointed.
The top of the Valanginian (the base of the Hauterivian) is at the first appearance of the ammonite genus Acanthodiscus.{{Citation needed|date=February 2024|reason=Citation needed for the entire above section, where none are provided}}
=Subdivision=
The Valanginian is often subdivided in Lower and Upper substages. The Upper substage begins at the first appearance of ammonite species Saynoceras verrucosum and the major marine transgression Va3.
In the Tethys domain, the Valanginian stage contains five ammonite biozones:
- zone of Criosarasinella furcillata
- zone of Neocomites peregrinus
- zone of Saynoceras verrucosum
- zone of Busnardoites campylotoxus
- zone of Tirnovella pertransiens {{Citation needed|date=February 2024|reason=Citation needed for the entire above section, where none are provided}}
Flora
The oldest fossils that can definitely be attributed to the clade Angiospermae (flowering plants) are dated to the Late Valanginian.{{cite journal | vauthors = Coiro M, Doyle JA, Hilton J | title = How deep is the conflict between molecular and fossil evidence on the age of angiosperms? | journal = The New Phytologist | volume = 223 | issue = 1 | pages = 83–99 | date = July 2019 | pmid = 30681148 | doi = 10.1111/nph.15708 | doi-access = free | bibcode = 2019NewPh.223...83C }}
References
=Notes=
{{reflist}}
=Literature=
- {{aut|Gradstein, F.M.; Ogg, J.G. & Smith, A.G.}}; (2004): A Geologic Time Scale 2004, Cambridge University Press.
External links
- [http://www.stratigraphy.org/bak/geowhen/stages/Valanginian.html GeoWhen Database - Valanginian]
- [http://stratigraphy.science.purdue.edu/charts/Timeslices/4_Mid-Cret.pdf Mid-Cretaceous timescale] and ühttp://stratigraphy.science.purdue.edu/charts/Timeslices/5_JurCret.pdf Jurassic-Cretaceous timescale], at the website of the subcommission for stratigraphic information of the ICS
- [https://web.archive.org/web/20060518101714/http://norges.uio.no/timescale/Fig18.1_Cret_colC.pdf Stratigraphic chart of the Lower Cretaceous], at the website of Norges Network of offshore records of geology and stratigraphy
{{Cretaceous Footer}}
{{Geological history|p|m}}
Category:Cretaceous geochronology
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