Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), approximately. The Aptian succeeds the Barremian and precedes the Albian, all part of the Lower/Early Cretaceous.
| Aptian | |||||||||
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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 | Not formally defined | ||||||||
| Lower boundary definition candidates |
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| Lower boundary GSSP candidate section(s) | Gorgo a Cerbara, Piobbico, Central Apennines, Italy | ||||||||
| Upper boundary definition | FAD of the Planktonic Foraminifer Microhedbergella renilaevis | ||||||||
| Upper boundary GSSP | Col de Pré-Guittard section, Arnayon, Drôme, France 44.4964°N 5.3114°E | ||||||||
| Upper GSSP ratified | April 2016 | ||||||||
The Aptian partly overlaps the upper part of the Western European Urgonian Stage.
The Selli Event, also known as OAE1a, was one of two oceanic anoxic events in the Cretaceous Period, which occurred around 120 Ma and lasted approximately 1 to 1.3 million years, being marked by enhanced silicate weathering, as well as ocean acidification. The Aptian extinction was a minor extinction event hypothesized to have occurred around 116 to 117 Ma.