Chaotian (geology)

{{Short description|Proposed era of the Hadean eon}}

{{Infobox geologic timespan

| name = Chaotian

| top_bar = all time

| time_start = 4568

| time_end = 4404

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| subdivisions = See text

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| celestial_body = Earth

| usage = Proposed subdivision of the Hadean eon

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| chrono_unit = Era

| strat_unit = Erathem

| proposed_by = C. Goldblatt, K. J. Zahnle, N. H. Sleep, and E. G. Nisbet, 2010

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| lower_boundary_def = Formation of the Earth

| lower_stratotype_location =

| upper_boundary_def = Collision between Proto-Earth and the Protoplanet Theia

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The Chaotian is a proposed time division of the geologic time scale. First proposed in 2010{{cite journal|last1=Goldblatt|first1=C.|last2=Zahnle|first2=K.J.|last3=Sleep|first3=N.H.|last4=Nisbet|first4=E.G.|date=2 February 2010|title=The Eons of Chaos and Hades|url=https://www.solid-earth.net/1/1/2010/se-1-1-2010.html|journal=Solid Earth|volume=1|issue=1|pages=1–3|bibcode=2010SolE....1....1G|doi=10.5194/se-1-1-2010|doi-access=free}} as an eon, it is named after Chaos, the primeval void in Greek mythology. This proposal defines the Chaotian eon as a Solar System-wide time between the initiation of planetary formation and the hypothesised collision of the trojan dwarf planet Theia with the proto-Earth.

A revised proposal in 2012{{Citation|last=Van Kranendonk|first=Martin J.|title=A Chronostratigraphic Division of the Precambrian|date=2012|url=https://linkinghub.elsevier.com/retrieve/pii/B9780444594259000160|work=The Geologic Time Scale|pages=299–392|publisher=Elsevier|language=en|doi=10.1016/b978-0-444-59425-9.00016-0|isbn=978-0-444-59425-9|access-date=2020-07-31|others=Altermann, Wladyslaw; Beard, Brian L.; Hoffman, Paul F.; Johnson, Clark M.; Kasting, James F.; Melezhik, Victor A.; Nutman, Allen; Papineau, Dominic; Pirajno, Franco}} suggested the Chaotian as the first era of the Hadean representing the time between the formation of the Solar System c. 4.567 Ga{{Cite journal|last1=Connelly|first1=J.N.|last2=Bollard|first2=J.|last3=Bizzarro|first3=M.|date=2017|title=Pb–Pb chronometry and the early Solar System|journal=Geochimica et Cosmochimica Acta|language=en|volume=201|pages=345–363|doi=10.1016/j.gca.2016.10.044|doi-access=free|bibcode=2017GeCoA.201..345C }} and the oldest preserved crustal material on Earth, a detrital zircon c. 4.404 Ga{{cite journal|last1=Wilde|first1=Simon A.|last2=Valley|first2=John W.|last3=Peck|first3=William H.|last4=Graham|first4=Colin M.|date=11 January 2001|title=Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago|journal=Nature|volume=409|issue=6817|pages=175–178|bibcode=2001Natur.409..175W|doi=10.1038/35051550|pmid=11196637|s2cid=4319774}} from the Jack Hills of the Narryer terrane in Western Australia.

{{As of|2023|09}}, neither proposal had been adopted or officially ratified by the International Union of Geological Sciences.{{cite web | url=https://stratigraphy.org/chart | title=International Commission on Stratigraphy }}