|Subdivisions of the Quaternary System|
The Gelasian is an age in the international geologic timescale or a stage in chronostratigraphy, being the earliest or lowest subdivision of the Quaternary period/system and Pleistocene epoch/series. It spans the time between 2.588 ± 0.005 Ma (million years ago) and 1.806 ± 0.005 Ma. It follows the Piacenzian stage (part of the Pliocene) and is followed by the Calabrian stage.
During the Gelasian the Red Crag of Butley and Newbourn and the Norwich and Weybourne Crags, all from East Anglia (England) were deposited. The Gelasian is an equivalent of the Praetiglian and Tiglian stages as defined in the Netherlands, which are commonly used in northwestern Europe.
The Gelasian was introduced in the geologic timescale in 1998. It is named after the Sicilian city of Gela in the south of the island. In 2009 it was moved from the Pliocene to the Pleistocene so that the geologic time scale would be more consistent with the key changes in Earth's climate, oceans, and biota that occurred 2.588 million years ago.
The base of the Gelasian is defined magnetostratigraphically as the base of the Matuyama (C2r) chronozone (at the Gauss-Matuyama magnetostratigraphic boundary), isotopic stage 103. Above this line notable extinctions of the calcareous nanofossils occur: Discoaster pentaradiatus and Discoaster surculus. The GSSP for the Gelasian is located at the Monte Sant Nicola near Gela.
The top of the Gelasian is defined magnetostratigraphically as the end of the Olduvai (C2n) chronozone, and faunally as the extinction level of the calcareous nanofossil Discoaster brouweri (base of biozone CN13). Above the Gelasian as the first occurrences of the calcareous nanofossil Gephyrocapsa sp. and the extinction level of the planktonic foraminifer Globigerinoides extremus.
- Cohen, K.M.; Finney, S.C.; Gibbard, P.L.; Fan, J.-X. "International Chronostratigraphic Chart". International Commission on Stratigraphy. Retrieved July 10, 2018.
- "IUGS ratifies Holocene". Retrieved 18 August 2018.
- "announcement ICS chart v2018/07". Retrieved 9 August 2018.
- Gelasian at the GeoWhen database
- The Gelasian was first proposed by Rio et al. (1998)
- Gibbard, Philip L.; Head, Martin J.; Walker, Michael J. C. (2009), "Formal ratification of the Quaternary System/Period and the Pleistocene Series/Epoch with a base at 2.58 Ma", Journal of Quaternary Science, 25 (2): 96, doi:10.1002/jqs.1338
- Gradstein et al. (2005), p. 28; Rio et al. (1998)
- Gradstein et al. (2005); Rio et al. (1998)
- Gradstein, Felix M.; Ogg, James G. & Smith, Alan G. (eds.) (2005) A Geologic Time Scale 2004, Cambridge University Press, Cambridge, UK, ISBN 0-521-78142-6
- Rio, Domenico; Sprovieri, Rodolfo; Castradori, Davide; and Di Stefano, Enrico; 1998. The Gelasian Stage (Upper Pliocene): A new unit of the global standard chronostratigraphic scale. Episodes, 21(2): 82-87
|This geochronology article is a stub. You can help Wikipedia by expanding it.|