Asselian
In the geologic timescale, the Asselian is the earliest geochronologic age or lowermost chronostratigraphic stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Asselian lasted between 298.9 and 293.52 million years ago (Ma). It was preceded by the Gzhelian (the latest or uppermost subdivision in the Carboniferous) and followed by the Sakmarian.
| Asselian | |||||||||||||
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| Chronology | |||||||||||||
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| Etymology | |||||||||||||
| Name formality | Formal | ||||||||||||
| Usage information | |||||||||||||
| Celestial body | Earth | ||||||||||||
| Regional usage | Global (ICS) | ||||||||||||
| Time scale(s) used | ICS Time Scale | ||||||||||||
| Definition | |||||||||||||
| Chronological unit | Age | ||||||||||||
| Stratigraphic unit | Stage | ||||||||||||
| Time span formality | Formal | ||||||||||||
| Lower boundary definition | FAD of the Conodont Streptognathodus isolatus within the morphotype Streptognathodus wabaunsensis chronocline | ||||||||||||
| Lower boundary GSSP | Aidaralash, Ural Mountains, Kazakhstan 50.2458°N 57.8914°E | ||||||||||||
| Lower GSSP ratified | 1996 | ||||||||||||
| Upper boundary definition | FAD of the Conodont Mesogondolella monstra | ||||||||||||
| Upper boundary GSSP | Usolka section, Southern Urals, Russia. 53.9247°N 56.7287°E | ||||||||||||
| Upper GSSP ratified | 2018 | ||||||||||||
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