Turonian
{{Short description|Second age of the Late Cretaceous epoch}}
{{Infobox geologic timespan
| name = Turonian
| color = Turonian
| time_start = 93.9
| time_end = 89.8
| time_end_uncertainty = 0.3
| image_map = LateCretaceousMap.jpg
| caption_map = Paleogeography of the late Turonian (90 Ma), showing the high sea level at the time
| image_outcrop =
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| timeline = Cretaceous
| formerly_part_of =
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| name_formality = Formal
| name_accept_date =
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| celestial_body = earth
| usage = Global (ICS)
| timescales_used = ICS Time Scale
| formerly_used_by =
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| chrono_unit = Age
| strat_unit = Stage
| proposed_by =
| type_section =
| timespan_formality = Formal
| lower_boundary_def = FAD of the Ammonite Watinoceras devonense
| lower_gssp_location = Rock Canyon, Colorado, USA
| lower_gssp_coords = {{Coord|38.2822|N|104.7275|W|display=inline}}
| upper_boundary_def = Not formally defined
| upper_def_candidates = FAD of the Inoceramid Bivalve Cremnoceramus rotundatus
| upper_gssp_candidates =
- Słupia Nadbrzeżna, Poland
- Pueblo, Colorado, USA
- Salzgitter-Salder quarry, Germany
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The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous Epoch, or a stage in the Upper Cretaceous Series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma (million years ago). The Turonian is preceded by the Cenomanian Stage and underlies the Coniacian Stage.See Gradstein et al. (2004) for a detailed description of the ICS' timescale
At the beginning of the Turonian an oceanic anoxic event (OAE 2) took place, also referred to as the Cenomanian-Turonian boundary event or the "Bonarelli Event".{{cite journal |last1=Cetean |first1=Claudia G. |last2=Balc |first2=Ramona |last3=Kaminski |first3=Michael A. |last4=Filipescu |first4=Sorin |title=Biostratigraphy of the Cenomanian-Turonian boundary in the Eastern Carpathians (Dâmboviţa Valley): preliminary observations |journal=Studia Universitatis Babeş-Bolyai, Geologia |date=August 2008 |volume=53 |issue=1 |pages=11–23 |url=http://discovery.ucl.ac.uk/18643/|doi=10.5038/1937-8602.53.1.2 |doi-access=free}} Sea level fall took place in the latter part of the Turonian from the highstand at the beginning of the Turonian.{{cite journal |last1=Wiese |first1=Frank |last2=Kröger |first2=Björn |date=January 1998 |title=Evidence for a shallowing event in the Upper Turonian (Cretaceous) Mytiloides scupini Zone of northern Germany |url=https://www.researchgate.net/publication/279594550 |journal=Acta Palaeontologica Polonica |volume=48 |issue=3 |pages=265–284 |access-date=15 December 2023}}
Stratigraphic definition
Image:Turonian Jerusalem Stone 031612.JPG, southern Israel; a variety of Jerusalem stone (meleke).]]
The Turonian (French: Turonien) was defined by the French paleontologist Alcide d'Orbigny (1802–1857) in 1842. Orbigny named it after the French city of Tours in the region of Touraine (department Indre-et-Loire), which is the original type locality.{{Citation needed|date=February 2024|reason=Citation needed for the entire above section, where none are provided}}
The base of the Turonian Stage is defined as the place where the ammonite species Watinoceras devonense first appears in the stratigraphic column. The official reference profile (the GSSP) for the base of the Turonian is located in the Rock Canyon anticline near Pueblo, Colorado (United States, coordinates: 38° 16' 56" N, 104° 43' 39" W).The GSSP was established by Kennedy et al. (2005)
The top of the Turonian Stage (the base of the Coniacian) is defined as the place in the stratigraphic column where the inoceramid bivalve species Cremnoceramus rotundatus first appears.
=Subdivision=
The Turonian is sometimes subdivided in Lower/Early, Middle and Upper/Late substages or subages. In the Tethys domain, it contains the following ammonite biozones:
- zone of Subprionocyclus neptuni (in the Upper Turonian)
- zone of Collignoniceras woollgari (in the Middle Turonian)
- zone of Mammites nodosoides
- zone of Watinoceras coloradoense or Watinoceras devonense (last two both in the Lower Turonian)
Other important index fossils are species of the inoceramid genus Inoceramus (I. schloenbachi, I. lamarcki and I. labiatus). Inoceramids are bivalve Mollusca related to today's mussels.{{Citation needed|date=February 2024|reason=Citation needed for the entire above section, where none are provided}}
References
{{reflist}}
=Literature=
- {{aut|Gradstein, F.M.; Ogg, J.G. & Smith, A.G.}}; 2004: A Geologic Time Scale 2004, Cambridge University Press.
- {{aut|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., Episodes 28(2): pp 93–104.
External links
- [http://www.stratigraphy.org/bak/geowhen/stages/Turonian.html GeoWhen Database - Turonian]
- [http://stratigraphy.science.purdue.edu/charts/Timeslices/3_Late_Cret.pdf Late Cretaceous timescale], at the website of the subcommission for stratigraphic information of the ICS
- Stratigraphic charts of the Cretaceous: [https://web.archive.org/web/20040511104934/http://norges.uio.no/timescale/Fig18.1_Cret_colA.pdf] and [https://web.archive.org/web/20040511055802/http://norges.uio.no/timescale/Fig18.1_Cret_colB.pdf], at the website of Norges Network of offshore records of geology and stratigraphy
- [http://www.foraminifera.eu/querydb.php?stage=Turonian&aktion=suche Turonian Microfossils: 48 images of Foraminifera]
{{Cretaceous Footer}}
{{Geological history|p|m}}