Chibanian

The Chibanian, widely known by its previous designation of Middle Pleistocene, is an age in the international geologic timescale or a stage in chronostratigraphy, being a division of the Pleistocene epoch within the ongoing Quaternary period.[4] The Chibanian name was officially ratified in January 2020. It is currently estimated to span the time between 0.770 Ma (770,000 years ago) and 0.126 Ma (126,000 years ago), also expressed as 770–126 ka. It includes the transition in palaeoanthropology from the Lower to the Middle Palaeolithic over 300 ka.

Chibanian
0.774 – 0.129 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Chronology
Epochs in the Quaternary Period -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 — C e n o z o i c N Q u a t e r n a r y P C P l e i s t o c e n e ↓Holocene Piacenzian Gelasian Calabrian Chibanian "Upper"               ← Meghalayan Northgrippian Greenlandian Epochs of the Quaternary Period.[1][2] Axis scale: millions of years ago.
Etymology
Name formality	Formal
Name ratified	January 2020
Synonym(s)	Middle Pleistocene Ionian
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	1.1 m below the directional midpoint of the Brunhes-Matuyama magnetic reversal
Lower boundary GSSP	Chiba, Japan 35.2943°N 140.1465°E
GSSP ratified	January 2020[3]
Upper boundary definition	Not formally defined
Upper boundary definition candidates	Marine Isotope Substage 5e
Upper boundary GSSP candidate section(s)	None

The Chibanian is preceded by the Calabrian and succeeded by the proposed Tarantian.[1] The beginning of the Chibanian is the Brunhes–Matuyama reversal, when the Earth's magnetic field last underwent reversal.[5] It ends with the onset of the Eemian interglacial period (Marine Isotope Stage 5).[6]

The term Middle Pleistocene was in use as a provisional or "quasi-formal" designation by the International Union of Geological Sciences (IUGS). While the three lowest ages of the Pleistocene, the Gelasian, Calabrian and Chibanian have been officially defined, the Late Pleistocene has yet to be formally defined, along with consideration of a proposed Anthropocene sub-division of the Holocene.[7]

Definition process

The International Union of Geological Sciences (IUGS) had previously proposed replacement of the Middle Pleistocene by an Ionian Age based on strata found in Italy. In November 2017, however, the Chibanian (based on strata at a site in Chiba Prefecture, Japan) replaced the Ionian as the Subcommission on Quaternary Stratigraphy's preferred GSSP proposal for the age that should replace the Middle Pleistocene sub-epoch.[8] The "Chibanian" name was ratified by the IUGS in January 2020.[4]

Palaeoanthropology

The Chibanian includes the transition in palaeoanthropology from the Lower to the Middle Palaeolithic: i.e., the emergence of Homo sapiens sapiens between 300 ka and 400 ka.[9] The oldest known human DNA dates to the Middle Pleistocene, around 430,000 years ago. This is the oldest found, as of 2016.[10]

Chronology

Age	paleoclimate	glaciation	palaeoanthropology
790–761 ka	MIS 19	Günz (Elbe) glaciation	Peking Man (Homo erectus)
761–712 ka	MIS 18
712–676 ka	MIS 17
676–621 ka	MIS 16
621–563 ka	MIS 15	Gunz-Haslach interglacial	Heidelberg Man (Homo heidelbergensis), Bodo cranium
563–524 ka	MIS 14
524–474 ka	MIS 13	end of Cromerian (Günz-Mindel) interglacial	Boxgrove Man (Homo heidelbergensis)
474–424 ka	MIS 12	Anglian Stage in Britain; Haslach glaciation	Tautavel Man (Homo erectus)
424–374 ka	MIS 11	Hoxnian (Britain), Yarmouthian (North America)	Swanscombe Man (Homo heidelbergensis)
374–337 ka	MIS 10	Mindel glaciation, Elster glaciation, Riss glaciation
337–300 ka	MIS 9	Purfleet Interglacial in Britain	Mousterian
300–243 ka	MIS 8		Irhoud 1 (Homo sapiens); Middle Paleolithic; Haplogroup A (Y-DNA)
243–191 ka	MIS 7	Aveley Interglacial in Britain	Galilee Man; Haua Fteah
191–130 ka	MIS 6	Illinoian Stage	Herto Man (Homo sapiens); Macro-haplogroup L (mtDNA); Mousterian
130–123 ka	MIS 5e	peak of Eemian interglacial sub-stage, or Ipswichian in Britain	Klasies River Caves; Sangoan

See also

• Mid-Pleistocene Transition
• 100,000-year problem
• Pleistocene megafauna

References

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. Subcommission on Quaternary Stratigraphy (SQS). 41 (4): 213–223. doi:10.18814/epiiugs/2018/018016. Retrieved 11 November 2019.
3. "Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Retrieved 26 December 2020.
4. Hornyak, Tim (30 January 2020). "Japan Puts Its Mark on Geologic Time with the Chibanian Age". Eos – Earth & Space Science News. American Geophysical Union. Retrieved 31 January 2020.
5. Gradstein, Felix M.; Ogg, James G.; Smith, Alan G., eds. (2004). A Geological Time Scale 2004 (3rd ed.). Cambridge: Cambridge University Press. p. 28. ISBN 9780521786737.
6. D. Dahl-Jensen & others (2013). "Eemian interglacial reconstructed from a Greenland folded ice core" (PDF). Nature. 493 (7433): 489–494. Bibcode:2013Natur.493..489N. doi:10.1038/nature11789. PMID 23344358. S2CID 4420908.
7. P. L. Gibbard (17 April 2015). "The Quaternary System/Period and its major sub-divisions". ScienceDirect. Elsevier BV. pp. 686–688. Retrieved 13 November 2019.
8. "Japan-based name 'Chibanian' set to represent geologic age of last magnetic shift". The Japan Times. 14 November 2017. Retrieved 13 November 2019.
9. D. Richter & others (8 June 2017). "The Age of Hominin Fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age". Nature. 546 (7657): 293–296. doi:10.1038/nature22335. PMID 28593967. S2CID 205255853..
10. Crew, Bec (15 March 2016). "The Oldest Human Genome Ever Has Been Sequenced, And It Could Rewrite Our History". ScienceAlert. Retrieved 5 June 2019.