The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya (million years ago) and 83.6 ± 0.7 mya. The Santonian is preceded by the Coniacian and is followed by the Campanian.[3]
| Santonian | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 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 | FAD of the Inoceramid Bivalve Cladoceramus undulatoplicatus | ||||||||
| Lower boundary GSSP | Olazagutia, Spain 42°52′00″N 2°11′48″W / 42.8668°N 2.1968°W | ||||||||
| GSSP ratified | January 2013[2] | ||||||||
| Upper boundary definition | Not formally defined | ||||||||
| Upper boundary definition candidates | LAD of the Crinoid Marsupites testudinarius | ||||||||
| Upper boundary GSSP candidate section(s) |
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Stratigraphic definitionEdit
The Santonian Stage was established by French geologist Henri Coquand in 1857. It is named after the city of Saintes in the region of Saintonge, where the original type locality is located.[4]
The base of the Santonian Stage is defined by the appearance of the inoceramid bivalve Cladoceramus undulatoplicatus. The GSSP (official reference profile) for the base of the Santonian Stage is located near Olazagutia, Spain; it was ratified by the Subcommission on Cretaceous Stratigraphy in 2012.[4] The Santonian's top (the base of the Campanian Stage) is informally marked by the extinction of the crinoid Marsupites testudinarius.[5] As of 2022[update], a GSSP for the top of the Santonian has not been ratified.[6]
SubdivisionEdit
The Santonian is sometimes subdivided into Lower, Middle and Upper Substages. In the Tethys domain the Santonian is coeval with a single ammonite biozone: that of Placenticeras polyopsis. Biostratigraphy based on inoceramids, nanoplankton or forams is more detailed.
ReferencesEdit
NotesEdit
- ^ International Commission on Stratigraphy. "ICS - Chart/Time Scale". www.stratigraphy.org.
- ^ Lamolda, M.; Paul, C.; Peryt, D.; Pons, J. (March 2014). "The Global Boundary Stratotype and Section Point (GSSP) for the base of the Santonian Stage, "Cantera de Margas", Olazagutia, northern Spain". Episodes. 37 (1): 2–13. doi:10.18814/epiiugs/2014/v37i1/001. Retrieved 24 December 2020.
- ^ Gradstein et al. (2004)
- ^ a b Gradstein, F.M.; Ogg, J.G.; Schmitz, M.D.; Ogg, G.M., eds. (2020). Geologic Time Scale 2020. Elsevier. p. 1038. ISBN 978-0-12-824360-2.
- ^ Gradstein, F.M.; Ogg, J.G.; Schmitz, M.D.; Ogg, G.M., eds. (2020). Geologic Time Scale 2020. Elsevier. p. 1040. ISBN 978-0-12-824360-2.
- ^ "Stratigraphic Chart 2022" (PDF). International Stratigraphic Commission. February 2022. Retrieved 30 July 2022.
LiteratureEdit
- Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
External linksEdit
- GeoWhen Database - Santonian
- Late Cretaceous timescale, at the website of the subcommission for stratigraphic information of the ICS
- Stratigraphic chart of the Late Cretaceous, at the website of Norges Network of offshore records of geology and stratigraphy