Toarcian
The Toarcian is, in the ICS' geologic timescale, an age and stage in the Early or Lower Jurassic. It spans the time between 182.7 Ma (million years ago) and 174.7 ±0.8 Ma. It follows the Pliensbachian and is followed by the Aalenian.
| Toarcian | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 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 | Peniche, Portugal | ||||||||
| Lower boundary GSSP | FAD of the Ammonite D. (E.) simplex 39.3708°N 9.3853°W | ||||||||
| Lower GSSP ratified | 2014 | ||||||||
| Upper boundary definition | FAD of the Ammonites Leioceras opalinum and Leioceras lineatum | ||||||||
| Upper boundary GSSP | Fuentelsaz, Spain 41.1708°N 1.8333°W | ||||||||
| Upper GSSP ratified | 2000 | ||||||||
The Toarcian Age began with the Toarcian Oceanic Anoxic Event, a major anoxic event associated with marine extinctions and increased global temperatures that sets its fossil faunas apart from the previous Pliensbachian age. It is believed to have ended with a global cooling event known as the Comptum Cooling Event, although whether it represented a worldwide event is controversial.
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