Gelasian

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 2.58 Ma (million years ago) and 1.80 Ma. It follows the Piacenzian Stage (part of the Pliocene) and is followed by the Calabrian Stage.

Gelasian
2.58 – 1.80 (Ma) PreꞒ Ꞓ O S D C P T J K Pg N ↓
Chronology
−2.6 — – −2.4 — – −2.2 — – −2 — – −1.8 — – −1.6 — – −1.4 — – −1.2 — – −1 — – −0.8 — – −0.6 — – −0.4 — – −0.2 — – 0 — Cenozoic N Quaternary PC Pleistocene   Piacenzian Gelasian Calabrian Chibanian "Late"             ← Holocene Subdivision of the Quaternary according to the ICS, as of 2021. Vertical axis scale: millions of years ago.
Formerly part of	Tertiary Period/System Pliocene Epoch/Series
Etymology
Name formality	Formal
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Age
Stratigraphic unit	Stage
Time span formality	Formal
Lower boundary definition	Base of magnetic polarity chronozone C2r (Matuyama) Extinction of the Haptophytes Discoaster pentaradiatus and Discoaster surculus
Lower boundary GSSP	Monte San Nicola Section, Gela, Sicily, Italy 37°08′49″N 14°12′13″E / 37.1469°N 14.2035°E / 37.1469; 14.2035
Lower GSSP ratified	1996 (as base of Gelasian)
Upper boundary definition	Approximately 8 m after the end of magnetic polarity chronozone C2n (Olduvai).
Upper boundary GSSP	Vrica Section, Calabria, Italy 39°02′19″N 17°08′05″E / 39.0385°N 17.1348°E / 39.0385; 17.1348
Upper GSSP ratified	5 December 2011 (as base of Calabrian)

Definition

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 2.58 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 nannofossils 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 nannofossil 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

Climate

During the Gelasian the ice sheets in the Northern Hemisphere began to grow, which is seen as the beginning of the Quaternary ice age. Deep sea core samples have identified approximately 40 marine isotope stages (MIS 103 – MIS 64) during the age. Thus, there have probably been about 20 glacial cycles of varying intensity during the Gelasian.

Europe

In the regional glacial history of the Alps, this age is now called Biber. It corresponds to Pre-Tegelen and Tegelen in Northern Europe.

During the Gelasian, the Red Crag Formation of Butley, the Newbourn Crag, the Norwich Crag Formation and the Weybourne Crag Formation (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.

References

Notes

1. Cohen, K. M.; Finney, S. C.; Gibbard, P. L.; Fan, J.-X. (January 2020). "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. Retrieved 23 February 2020.
2. Mike Walker; et al. (December 2018). "Formal ratification of the subdivision of the Holocene Series/Epoch (Quaternary System/Period)" (PDF). Episodes. 41 (4). Subcommission on Quaternary Stratigraphy (SQS): 213–223. doi:10.18814/epiiugs/2018/018016. Retrieved 11 November 2019.
3. Rio, Domenico; R. Sprovieri; D. Castradori; E. Di Stefano (1998). "The Gelasian Stage (Upper Pliocene): A new unit of the global standard chronostratigraphic scale". Episodes. 21 (2): 82–87. doi:10.18814/epiiugs/1998/v21i2/002.
4. Cita, Maria; Gibbard, Philip; Head, Martin (September 2012). "Formal ratification of the GSSP for the base of the Calabrian Stage (second stage of the Pleistocene Series, Quaternary System)". Episodes. 35 (3): 388–397. doi:10.18814/epiiugs/2012/v35i3/001. hdl:10261/250367. Retrieved 26 December 2020.
5. "Stratigraphic Chart 2022" (PDF). International Stratigraphic Commission. February 2022. Retrieved 4 June 2022.
6. Rio, D., Sprovieri, R., Castradori, D., Di Stefano, E. "The Gelasian Stage (Upper Pliocene): A new unit of the global standard chronostratigraphic scale", Episodes, Vol. 21, No. 1, March 1998. pp 82-87. Retrieved March 18, 2020.
7. 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
8. Gradstein et al. (2005), p. 28
9. Gradstein et al. (2005)
10. German Stratigraphic Commission: Stratigraphische Tabelle von Deutschland 2016

Literature

• 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