Turonian
| Turonian | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 Paleogeography of the late Turonian (90 Ma), showing the high sea level at the time | |||||||||
| 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 | FADof theAmmoniteWatinoceras devonense | ||||||||
| Lower boundary GSSP | Rock Canyon,Colorado,USA 38°16′56″N104°43′39″W/ 38.2822°N 104.7275°W | ||||||||
| Lower GSSP ratified | September 2003[2] | ||||||||
| Upper boundary definition | Not formally defined | ||||||||
| Upper boundary definition candidates | FAD of theInoceramidBivalveCremnoceramus rotundatus | ||||||||
| Upper boundary GSSP candidate section(s) |
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TheTuronianis, in theICS'geologic timescale,the secondagein theLate CretaceousEpoch,or astagein theUpper CretaceousSeries.It spans the time between 93.9 ± 0.8Maand 89.8 ± 1 Ma (million years ago). The Turonian is preceded by theCenomanianStage and underlies theConiacianStage.[3]
At the beginning of the Turonian anoceanic anoxic event(OAE 2) took place, also referred to as theCenomanian-Turonian boundary eventor the "Bonarelli Event".[4]Sea level fall took place in the latter part of the Turonian from the highstand at the beginning of the Turonian.[5]
Stratigraphic definition
[edit]
The Turonian (French:Turonien) was defined by theFrenchpaleontologistAlcide d'Orbigny(1802–1857) in 1842. Orbigny named it after the French city ofToursin the region ofTouraine(departmentIndre-et-Loire), which is the originaltype locality.[citation needed]
The base of the Turonian Stage is defined as the place where theammonitespeciesWatinoceras devonensefirst appears in thestratigraphic column.The official reference profile (theGSSP) for the base of the Turonian is located in the Rock Canyon anticline nearPueblo, Colorado(United States, coordinates: 38° 16' 56 "N, 104° 43' 39" W).[6]
The top of the Turonian Stage (the base of the Coniacian) is defined as the place in the stratigraphic column where theinoceramidbivalvespeciesCremnoceramus rotundatusfirst appears.
Subdivision
[edit]The Turonian is sometimes subdivided in Lower/Early, Middle and Upper/Late substages or subages. In theTethys domain,it contains the following ammonitebiozones:
- zone ofSubprionocyclus neptuni(in the Upper Turonian)
- zone ofCollignoniceras woollgari(in the Middle Turonian)
- zone ofMammites nodosoides
- zone ofWatinoceras coloradoenseorWatinoceras devonense(last two both in the Lower Turonian)
Other importantindex fossilsare species of the inoceramidgenusInoceramus(I. schloenbachi,I. lamarckiandI. labiatus). Inoceramids are bivalveMolluscarelated to today'smussels.[citation needed]
References
[edit]- ^International Commission on Stratigraphy."ICS - Chart/Time Scale".stratigraphy.org.
- ^Kennedy, W. J.; I. Walaszczyk; W. A. Cobban (2005)."The Global Boundary Stratotype Section and Point for the base of the Turonian Stage of the Cretaceous: Pueblo, Colorado, U.S.A."(PDF).Episodes.28(2): 93–104.doi:10.18814/epiiugs/2005/v28i2/003.
- ^See Gradsteinet al.(2004) for a detailed description of the ICS' timescale
- ^Cetean, Claudia G.; Balc, Ramona; Kaminski, Michael A.; Filipescu, Sorin (August 2008)."Biostratigraphy of the Cenomanian-Turonian boundary in the Eastern Carpathians (Dâmboviţa Valley): preliminary observations".Studia Universitatis Babeş-Bolyai, Geologia.53(1): 11–23.doi:10.5038/1937-8602.53.1.2.
- ^Wiese, Frank; Kröger, Björn (January 1998)."Evidence for a shallowing event in the Upper Turonian (Cretaceous) Mytiloides scupini Zone of northern Germany".Acta Palaeontologica Polonica.48(3): 265–284.Retrieved15 December2023.
- ^The GSSP was established by Kennedyet al.(2005)
Literature
[edit]- Gradstein, F.M.; Ogg, J.G. & Smith, A.G.;2004:A Geologic Time Scale 2004,Cambridge University Press.
- Kennedy, W.J.; Walaszczyk, I. & Cobban, W.A.;2005:The Global Boundary Stratotype Section and Point for the base of the Turonian Stage of the Cretaceous: Pueblo, Colorado, U.S.A.,Episodes28(2): pp 93–104.
External links
[edit]- GeoWhen Database - Turonian
- Late Cretaceous timescale,at the website of the subcommission for stratigraphic information of the ICS
- Stratigraphic charts of the Cretaceous:[1]and[2],at the website of Norges Network of offshore records of geology and stratigraphy
- Turonian Microfossils: 48 images of Foraminifera
