| Tortonian | |
| Color: | Tortonian |
| Time Start: | 11.63 |
| Time End: | 7.246 |
| Timeline: | Neogene |
| Formerly Part Of: | Tertiary Period/System |
| Name Formality: | Formal |
| Celestial Body: | earth |
| Usage: | Global (ICS) |
| Timescales Used: | ICS Time Scale |
| Chrono Unit: | Age |
| Strat Unit: | Stage |
| Timespan Formality: | Formal |
| Lower Boundary Def: | LAD of the Haptophyte Discoaster kugleri |
| Lower Gssp Location: | Monte dei Corvi Beach section, Ancona, Italy |
| Lower Gssp Accept Date: | 2003[1] |
| Upper Boundary Def: |
|
| Upper Gssp Location: | Oued Akrech section, Rabat, Morocco |
| Upper Gssp Accept Date: | January 2000[2] |
The Tortonian is in the geologic time scale an age or stage of the late Miocene that spans the time between . It follows the Serravallian and is followed by the Messinian.
The Tortonian roughly overlaps with the regional Pannonian Stage of the Paratethys timescale of Central Europe. It also overlaps the upper Astaracian, Vallesian and lower Turolian European land mammal ages, the upper Clarendonian and lower Hemphillian North American land mammal ages and the upper Chasicoan and lower Huayquerian South American land mammal ages.
The Tortonian was introduced by Swiss stratigrapher Karl Mayer-Eymar in 1858. It was named after the Italian city of Tortona in the Piedmont region.
The base of the Tortonian Stage is at the last common appearance of calcareous nanoplankton Discoaster kugleri and planktonic foram Globigerinoides subquadratus. It is also associated with the short normal polarized magnetic chronozone C5r.2n. A GSSP for the Tortonian has been established in the Monte dei Corvi section near Ancona (Italy).[3]
The top of the Tortonian (the base of the Messinian) is at the first appearance of the planktonic foram species Globorotalia conomiozea and is stratigraphically in the middle of magnetic chronozone C3Br.1r.
In 2020, geologists reported two newly-identified supervolcano eruptions associated with the Yellowstone hotspot track, including the region's largest and most cataclysmic event - the Grey's Landing super-eruption - which had a volume of at least 2800km3 and occurred around 8.72 Ma.[4] [5]