Archean Eon
E43458
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.
Observed surface forms (3)
| Surface form | Occurrences |
|---|---|
| Archaean Eon | 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 (6)
Full triples — surface form annotated when it differs from this entity's canonical label.
this entity surface form:
Archaean Eon
this entity surface form:
Archeozoic Eon
this entity surface form:
Neoarchean Era