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
86.3 ± 0.5 – 83.6 ± 0.2 Ma
Chronology
Etymology
Name formalityFormal
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitAge
Stratigraphic unitStage
Time span formalityFormal
Lower boundary definitionFAD of the Inoceramid Bivalve Cladoceramus undulatoplicatus
Lower boundary GSSPOlazagutia, Spain
42°52′00″N 2°11′48″W / 42.8668°N 2.1968°W / 42.8668; -2.1968
GSSP ratifiedJanuary 2013[2]
Upper boundary definitionNot formally defined
Upper boundary definition candidatesLAD of the Crinoid Marsupites testudinarius
Upper boundary GSSP candidate section(s)

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, 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

  1. ^ International Commission on Stratigraphy. "ICS - Chart/Time Scale". www.stratigraphy.org.
  2. ^ 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.
  3. ^ Gradstein et al. (2004)
  4. ^ 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.
  5. ^ 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.
  6. ^ "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