In the

geologic timescale The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronol ...

, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.3 ± 2 Ma and 190.8 ± 1.5 Ma (million years ago). The Sinemurian is preceded by the

Hettangian The Hettangian is the earliest age and lowest stage of the Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (My ...

and is followed by the Pliensbachian. 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 Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

'' Vermiceras'' and ''

Metophioceras ''Metoioceras'' is an extinct genus of cephalopod belonging to the Ammonite subclass which lived during the Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest s ...

'' 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, east of Watchet, Somerset, England.See for the description of the GSSP Bloos & Page (2001) Eteoderoceras armatum sinemurian

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 ''Echioceras'' is an extinct genus of ammonites from the Early Jurassic of Europe and North America. Description Shell of ''Echioceras'' species can reach a diameter of about .. The narrow and broad evolute shell is reinforced by fine ribs on in ...

'' *zone of '' Oxynoticeras oxynotum'' *zone of '' Asteroceras obtusum'' *zone of '' Caenisites turneri'' *zone of ''

Arnioceras semicostatum ''Arnioceras'' is an extinct genus of large, evolute, discoidal ammonite from the Lower Jurassic. The shell is normally coiled so that all whorls are exposed. Sides bear strong sharp ribs that are straight until reaching the ventrolateral edg ...

'' *zone of '' Arietites bucklandi''

References

Sources

*; 2001: ''Global Stratotype Section and Point for base of the Sinemurian Stage (Lower Jurassic)'', Episodes 25(1), pp. 22–28
PDF
*; 2004: ''A Geologic Time Scale 2004'', Cambridge University Press. *; 1842: ''Paléontologie française. 1. Terrains oolitiques ou jurassiques'', Bertrand, Paris.

External links

GeoWhen Database - SinemurianLower 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 {{Geological history, p, m *02 Geological ages

Stratigraphic definitions

References

Sources

See also

External links