Neoarchean | |||||||||||||
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Chronology | |||||||||||||
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Proposed redefinition(s) | 2780–2420 Ma Gradstein et al., 2012 | ||||||||||||
Proposed subdivisions | Methanian Period, 2780–2630 Ma Gradstein et al., 2012 | ||||||||||||
Etymology | |||||||||||||
Name formality | Formal | ||||||||||||
Alternate spelling(s) | Neoarchaean | ||||||||||||
Usage information | |||||||||||||
Celestial body | Earth | ||||||||||||
Regional usage | Global (ICS) | ||||||||||||
Time scale(s) used | ICS Time Scale | ||||||||||||
Definition | |||||||||||||
Chronological unit | Era | ||||||||||||
Stratigraphic unit | Erathem | ||||||||||||
Time span formality | Formal | ||||||||||||
Lower boundary definition | Defined Chronometrically | ||||||||||||
Lower GSSA ratified | 1991[citation needed] | ||||||||||||
Upper boundary definition | Defined Chronometrically | ||||||||||||
Upper GSSA ratified | 1991[citation needed] |
The Neoarchean (/ˌniːoʊ.ɑːrˈkiːən/ NEE-oh-ar-KEE-ən; also spelled Neoarchaean) is the last geologic era in the Archean Eon that spans from 2800 to 2500 million years ago—the period being defined chronometrically and not referencing a specific level in a rock section on Earth. The era is marked by major developments in complex life and continental formation.