Bajocian
Template:Short description Template:Infobox geologic timespan
In the geologic timescale, the Bajocian is an age and stage in the Middle Jurassic. It lasted from approximately 170.9 ±0.8 Ma to around 168.2 ±1.2 Ma (million years ago). The Bajocian Age succeeds the Aalenian Age and precedes the Bathonian Age.[1]
Stratigraphic definitions
The Bajocian Stage takes its name from the Latin name (Bajocae) of the town of Bayeux, in the region of Normandy in France. The stage was named and introduced in scientific literature by French palaeontologist Alcide d'Orbigny in 1842.
The base of the Bajocian stage is defined as the place in the stratigraphic column where fossils of the ammonite genus Hyperlioceras first appear. A global reference profile (a GSSP) for the base is located at Murtinheira, close to Cabo Mondego in Portugal.[2] The top of the Bajocian (the base of the Bathonian) is at the first appearance of ammonite species Parkinsonia convergens.
Subdivision
The Bajocian is often divided into Lower/Early and Upper/Late subages or substages.
In the Tethys domain, the Bajocian contains seven ammonite biozones:
- zone of Parkinsonia parkinsoni
- zone of Garantiana garantiana
- zone of Strenoceras niortense
- zone of Stephanoceras humphriesianum
- zone of Sonninia propinquans
- zone of Witchellia laeviuscula
- zone of Hyperlioceras discites
References
Notes
<templatestyles src="Reflist/styles.css" />
Script error: No such module "Check for unknown parameters".
Literature
- <templatestyles src="smallcaps/styles.css"/>Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
- <templatestyles src="smallcaps/styles.css"/>Alcide d´Orbigny; 1842: Paléontologie française. 1. Terrains oolitiques ou jurassiques, 642 pp., Bertrand, Paris.
- <templatestyles src="smallcaps/styles.css"/>Pavia, G. & Enay, R.; 1997: Definition of the Aalenian-Bajocian Stage boundary, Episodes, 20(1): pp 16–22.
- <templatestyles src="smallcaps/styles.css"/>Sepkoski, J.; 2002: A compendium of fossil marine animal genera (entry on cephalopoda), Bulletins of American Paleontology 364, p 560.
- Script error: No such module "Citation/CS1".
External links
- GeoWhen Database - Bajocian
- Jurassic-Cretaceous and Lower Jurassic timescales, at the website of the subcommission for stratigraphic information of the ICS
- Stratigraphic chart of the Upper Jurassic, at the website of Norges Network of offshore records of geology and stratigraphy