Mesoarchean
| Mesoarchean | ||||||||||||||||
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A reconstruction of the Earth's continents during the middle Mesoarchean, c. 3 Ga. | ||||||||||||||||
Artist impression of the Archean eon | ||||||||||||||||
Banded iron formation created during the Mesoarchean era | ||||||||||||||||
| Chronology | ||||||||||||||||
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| Proposed redefinition(s) | 3490–2780 Ma Gradstein et al., 2012 | |||||||||||||||
| Proposed subdivisions | Vaalbaran Period, 3490–3020 Ma Gradstein et al., 2012 | |||||||||||||||
| Etymology | ||||||||||||||||
| Name formality | Formal | |||||||||||||||
| Alternate spelling(s) | Mesoarchaean | |||||||||||||||
| 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 | |||||||||||||||
| Upper boundary definition | Defined Chronometrically | |||||||||||||||
| Upper GSSA ratified | 1991 | |||||||||||||||
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The Mesoarchean (/ˌmiːzoʊ.ɑːrˈkiːən, ˌmɛzoʊ-/ MEE-zoh-ar-KEE-ən, MEZ-oh-, also spelled Mesoarchaean) is a geologic era in the Archean Eon, spanning 3,200 to 2,800 million years ago, which contains the first evidence of modern-style plate subduction and expansion of microbial life. The era is defined chronometrically and is not referenced to a specific level in a rock section on Earth.