Contents

Sinemurian

Second age of the Early Jurassic

Sinemurian
199.5 ± 0.3 – 192.9 ± 0.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Jurassic rock strata in the cliffs at East Quantoxhead, near the Sinemurian golden spike.
Chronology
−200 — – −195 — – −190 — – −185 — – −180 — – −175 — – −170 — – −165 — – −160 — – −155 — – −150 — – −145 — – Mesozoic T Jurassic K LT Early Middle Late EK Rhaetian Hettangian Sinemurian Pliensbachian Toarcian Aalenian Bajocian Bathonian Callovian Oxfordian Kimmeridgian Tithonian Berriasian       ← Triassic–Jurassic extinction event Subdivision of the Jurassic according to the ICS, as of 2022.[1] Vertical axis scale: millions of years ago.
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 Ammonites Vermiceras quantoxense and Vermiceras palmeri
Lower boundary GSSP	East 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 ratified	2000[2]
Upper boundary definition	FAD of the Ammonite species Bifericeras donovani and genus Apoderoceras
Upper boundary GSSP	Robin 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 ratified	March 2005[3]

In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic EpochorSeries. 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[edit]

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]

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:

• zone of Echioceras raricostatum
• zone of Oxynoticeras oxynotum
• zone of Asteroceras obtusum
• zone of Caenisites turneri
• zone of Arnioceras semicostatum
• zone of Arietites bucklandi

References[edit]

Sources[edit]

• 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[edit]

• Komlosaurus carbonis

External links[edit]

• GeoWhen Database - Sinemurian
• Lower Jurassic timescale, at the website of the subcommission for stratigraphic information of the ICS
• Stratigraphic chart of the Lower Jurassic, at the website of Norges Network of offshore records of geology and stratigraphy