| Toarcian | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Chronology | |||||||||
| |||||||||
| 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°22′15″N 9°23′07″W / 39.3708°N 9.3853°W | ||||||||
| Lower GSSP ratified | 2014[2] | ||||||||
| Upper boundary definition | FAD of the Ammonites Leioceras opalinum and Leioceras lineatum | ||||||||
| Upper boundary GSSP | Fuentelsaz, Spain 41°10′15″N 1°50′00″W / 41.1708°N 1.8333°W | ||||||||
| Upper GSSP ratified | 2000[3] | ||||||||
The Toarcian is, in the ICS' geologic timescale, an age and stage in the Early or Lower Jurassic. It spans the time between 184.2 Ma (million years ago) and 174.7 ±0.8 Ma.[4] It follows the Pliensbachian and is followed by the Aalenian.[5]
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.[6]
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