Archean Eon

E43458

geological eon

The Archean Eon is an ancient geological eon of Earth's history, spanning from about 4.0 to 2.5 billion years ago, characterized by the formation of the first stable continental crust and the earliest known life.

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All labels observed (5)

Label	Occurrences
Archean Eon canonical	17
Archaean Eon	1
Archean	1
Archeozoic Eon	1
Neoarchean Era	1

Statements (50)

Predicate	Object
instanceOf	geological eon ⓘ
alsoKnownAs	Archean Eon ⓘ surface form: Archaean Eon Archean Eon ⓘ surface form: Archeozoic Eon
associatedWith	formation of Pilbara Craton ⓘ formation of Superior Craton ⓘ formation of major cratons such as Kaapvaal Craton ⓘ
atmosphereComposition	dominated by nitrogen and carbon dioxide ⓘ very low molecular oxygen ⓘ
biosphere	dominated by prokaryotes ⓘ presence of cyanobacteria by late Archean ⓘ
characterizedBy	abundant komatiites ⓘ anoxic atmosphere ⓘ development of proto-continents ⓘ dominance of mafic and ultramafic rocks ⓘ earliest known life on Earth ⓘ early oceans ⓘ emergence of stable cratons ⓘ formation of first stable continental crust ⓘ high geothermal heat flow ⓘ limited free oxygen in atmosphere ⓘ microbial life ⓘ more intense volcanism than today ⓘ presence of greenstone belts ⓘ stromatolite formation ⓘ
climate	Sun fainter than today ⓘ possible greenhouse warming to keep oceans liquid ⓘ
contains	oldest known continental crust fragments ⓘ oldest known sedimentary rocks ⓘ oldest known stromatolites ⓘ oldest widely accepted microfossils ⓘ
duration	about 1.5 billion years ⓘ
endTime	2.5 billion years ago ⓘ
endTimeUpperBound	about 2,500 million years ago ⓘ
follows	Hadean Eon ⓘ
importance	records earliest preserved history of Earth’s crust ⓘ records origin and early evolution of life ⓘ
meaningOfName	ancient ⓘ
namedAfter	Greek word "archaios" ⓘ
oceanChemistry	likely rich in dissolved iron ⓘ
partOf	Precambrian Supereon ⓘ geologic time scale ⓘ
precedes	Proterozoic Eon ⓘ
startTime	4.0 billion years ago ⓘ
startTimeLowerBound	about 4,000 million years ago ⓘ
subdividedInto	Eoarchean Era ⓘ Mesoarchean Era ⓘ Neoarchean Era ⓘ Paleoarchean Era ⓘ
tectonics	early forms of plate tectonics debated ⓘ possible stagnant-lid or proto-plate tectonic regime ⓘ

Referenced by (21)

Full triples — surface form annotated when it differs from this entity's canonical label.

Proterozoic Eon → follows → Archean Eon ⓘ

Precambrian Supereon → includes → Archean Eon ⓘ

Precambrian Supereon → contains → Archean Eon ⓘ

this entity surface form: Neoarchean Era

Archean Eon → alsoKnownAs → Archean Eon ⓘ

this entity surface form: Archaean Eon

Archean Eon → alsoKnownAs → Archean Eon ⓘ

this entity surface form: Archeozoic Eon

Paleoproterozoic Era → follows → Archean Eon ⓘ

Laurentia → formed → Archean Eon ⓘ

Fennoscandian Shield → oldestRocksAge → Archean Eon ⓘ

Barberton Makhonjwa Mountains → geologicalAge → Archean Eon ⓘ

Kaapvaal Craton → geologicalEra → Archean Eon ⓘ

Hadean Eon → precedes → Archean Eon ⓘ

Cryptozoic → includes → Archean Eon ⓘ

Kalahari Craton → formedDuring → Archean Eon ⓘ

Paleoarchean Era → partOf → Archean Eon ⓘ

Eoarchean Era → partOf → Archean Eon ⓘ

Mesoarchean Era → partOf → Archean Eon ⓘ

Siderian Period → follows → Archean Eon ⓘ

Neoarchean Era → partOf → Archean Eon ⓘ

Neoarchean Era → isFinalEraOf → Archean Eon ⓘ

Pilbara Craton → geologicalAge → Archean Eon ⓘ

this entity surface form: Archean

Lalbagh Rock → geologicalAge → Archean Eon ⓘ