Sinemurian

Sinemurian
199.5 ± 0.3 – 192.9 ± 0.3 Ma
Jurassic rock strata in the cliffs at East Quantoxhead, near the Sinemurian golden spike.
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 Ammonites Vermiceras quantoxense and Vermiceras palmeri
Lower boundary GSSPEast Quantoxhead, West Somerset, England, UK
51°11′27″N 3°14′11″W / 51.1909°N 3.2364°W / 51.1909; -3.2364
Lower GSSP ratified2000[2]
Upper boundary definitionFAD of the Ammonite species Bifericeras donovani and genus Apoderoceras
Upper boundary GSSPRobin Hood's Bay, Yorkshire, England, UK
54°24′25″N 0°29′51″W / 54.4069°N 0.4975°W / 54.4069; -0.4975
Upper GSSP ratifiedMarch 2005[3]

In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.5 ±0.3 Ma and 192.9 ±0.3 Ma (million years ago).[4] The Sinemurian is preceded by the Hettangian and is followed by the Pliensbachian.[5]

In Europe the Sinemurian age, together with the Hettangian age, saw the deposition of the lower Lias, in Great Britain known as the Blue Lias.

Stratigraphic definitions

The Sinemurian Stage was defined and introduced into scientific literature by French palaeontologist Alcide d'Orbigny in 1842. It takes its name from the French town of Semur-en-Auxois, near Dijon. The calcareous soil formed from the Jurassic limestone of the region is in part responsible for the character of the classic Sancerre wines.

The base of the Sinemurian Stage is at the first appearance of the ammonite genera Vermiceras and Metophioceras in the stratigraphic record. A global reference profile (GSSP or golden spike) for the Sinemurian Stage is located in a cliff north of the hamlet of East Quantoxhead, 6 kilometers (3.7 mi) east of Watchet, Somerset, England.[6]

Eteoderoceras armatum, a Sinemurian ammonite

The top of the Sinemurian (the base of the Pliensbachian) is at the first appearances of the ammonite species Bifericeras donovani and ammonite genus Apoderoceras.

The Sinemurian contains six ammonite biozones in the Tethys domain:

References

  1. ^ "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. September 2023. Retrieved December 16, 2024.
  2. ^ Bloos, Gert; Page, Kevin (March 2002). "Global Stratotype Section and Point for base of the Sinemurian Stage (Lower Jurassic)". Episodes. 25 (1): 22–28. doi:10.18814/epiiugs/2002/v25i1/003. Retrieved 23 December 2020.
  3. ^ Meister, Christian; Aberhan, Martin; Blau, Joachim; Dommergues, Jean-Louis; Feist-Burkhardt, Susanne; Hailwood, Ernie; Hart, Malcolm; Hesselbo, Stephen; Hounslow, Mark; Hylton, Mark; Martin, Nicol; Page, Kevin; Price, Greg (June 2006). "The Global Boundary Stratotype Section and Point (GSSP) for the base of the Pliensbachian Stage (Lower Jurassic), Wine Haven, Yorkshire, UK". Episodes. 29 (2): 93–106. doi:10.18814/epiiugs/2006/v29i2/003. Retrieved 23 December 2020.
  4. ^ Benton, Michael J. (2012). Prehistoric Life. Edinburgh, Scotland: Dorling Kindersley. pp. 44–45. ISBN 978-0-7566-9910-9.
  5. ^ For a detailed geologic timescale see Gradstein et al. (2004)
  6. ^ See for the description of the GSSP Bloos & Page (2001)

Sources

  • Bloos, G. & Page, K.N.; 2001: Global Stratotype Section and Point for base of the Sinemurian Stage (Lower Jurassic), Episodes 25(1), pp. 22–28, PDF
  • Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
  • d´Orbigny, A.C.V.M.D.; 1842: Paléontologie française. 1. Terrains oolitiques ou jurassiques, Bertrand, Paris. (in French)

See also