The Tortonian is in the
geologic time scale
The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochro ...
an
age or
stage of the
late Miocene
The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...
that spans the time between 11.608 ± 0.005
Ma and 7.246 ± 0.005 Ma (million years ago).
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
The Clarendonian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 13,600,000 to 9,000,000 years BP, a period of .
It is us ...
and lower
Hemphillian
The Hemphillian North American Stage on the geologic timescale is a North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 10,300,000 to 4,900,000 years BP. It is usually considered t ...
North American land mammal ages and the upper
Chasicoan and lower
Huayquerian South American land mammal ages.
Definition
The Tortonian was introduced by Swiss
stratigrapher Karl Mayer-Eymar in 1858. It was named after the Italian city of
Tortona in the
Piedmont
Piedmont ( ; ; ) is one of the 20 regions of Italy, located in the northwest Italy, Northwest of the country. It borders the Liguria region to the south, the Lombardy and Emilia-Romagna regions to the east, and the Aosta Valley region to the ...
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
A Global Boundary Stratotype Section and Point (GSSP), sometimes referred to as a golden spike, is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. ...
for the Tortonian has been established in the Monte dei Corvi section near
Ancona
Ancona (, also ; ) is a city and a seaport in the Marche region of central Italy, with a population of around 101,997 . Ancona is the capital of the province of Ancona, homonymous province and of the region. The city is located northeast of Ro ...
(Italy).
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.
Geologic history
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 and occurred around 8.72 Ma.
Around 10 Ma, the inflow of
North Atlantic Deep Water (NADW) into the
Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...
increased significantly.
References
Notes
Literature
*; 2004: ''A Geologic Time Scale 2004'', Cambridge University Press.
*; 2005: ''The Global boundary Stratotype Section and Point (GSSP) of the Tortonian Stage (Upper Miocene) at Monte Dei Corvi'', Episodes 28, p. 6-17.
*; 1858: ''Versuch einer neuen Klassifikation der Tertiär-Gebilde Europa’s'', Verhandlungen der Schweizerischen Naturforschenden Gesellschaft, Jahresversammlung 1857, p. 70–71 & 165–199.
External links
GeoWhen Database - TortonianNeogene timescale
at the website of the subcommission for stratigraphic information of the ICS
Neogene timescale
at the website of the Norwegian network of offshore records of geology and stratigraphy
{{Geological history of Earth, p, c
*05
Miocene geochronology
Geological ages