Bathonian
| Bathonian | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Chronology | |||||||||
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| 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 Ammonite Gonolkites convergen | ||||||||
| Lower boundary GSSP | Ravin du Bès, Bas-Auran, Alpes de Haute, France 43°57′38″N 6°18′55″E / 43.9606°N 6.3153°E | ||||||||
| Lower GSSP ratified | July 2008[2] | ||||||||
| Upper boundary definition | FAD of the Ammonite genus Kepplerites | ||||||||
| Upper boundary GSSP candidate section(s) | |||||||||
In the geologic timescale the Bathonian is an age and stage of the Middle Jurassic. It lasted from approximately 168.2 ±1.2 Ma to around 165.3 ±1.1 Ma (million years ago). The Bathonian Age succeeds the Bajocian Age and precedes the Callovian Age.[3]
Stratigraphic definitions
[edit]The Bathonian Stage takes its name from Bath, a spa town in England built on Jurassic limestone (the Latinized form of the town name is Bathonium). The name was introduced in scientific literature by Belgian geologist d'Omalius d'Halloy in 1843. The original type locality was located near Bath. The French palaeontologist Alcide d'Orbigny was in 1852 the first to define the exact length of the stage.
The base of the Bathonian is at the first appearance of ammonite species Parkinsonia (Gonolkites) convergens in the stratigraphic column. The global reference profile for the base of the Bathonian (a GSSP) was ratified as Ravin du Bès, Bas-Auran area, Alpes de Haute Provence, France in 2009.[4] The top of the Bathonian (the base of the Callovian Stage) is at the first appearance of ammonite genus Kepplerites.
In the Tethys domain, the Bathonian contains eight ammonite biozones:
- zone of Clydoniceras discus
- zone of Hecticoceras retrocostatum
- zone of Cadomites bremeri
- zone of Morrisiceras morrisi
- zone of Tulites subcontractus
- zone of Procerites progracilis
- zone of Procerites aurigerus
- zone of Zigzagiceras zigzag
Rocks of Bathonian age are well developed in Europe: in the northwest and southwest oolite limestones are characteristically associated with coral-bearing, crinoidal and other varieties, and with some beds of clay. In the north and northeast, Russia, etc., clays, sandstones and ferruginous oolites prevail, some of the last being exploited for iron. They occur also in the extreme north of North America and in the Arctic regions, Greenland, Franz Josef Land, etc.; in Africa, Algeria, Tanzania, Madagascar and near the Cape of Good Hope (Enon Beds); in India, Rajputana and Gulf of Kutch, and in South America.[5]
The well-known Caen stone of Normandy and "Hauptrogenstein" of Swabia, as well as the "Eisenkalk" of northwest Germany, and "Klaus-Schichten" of the Austrian Alps, are of Bathonian age.[5]
References
[edit]Notes
[edit]- ^ "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy.
- ^ Fernández-López, Sixto Rafael; Pavia, Giulio; Erba, Elisabetta; Guiomar, Myette; Maria Helena Henriques; Lanza, Roberto; Mangold, Charles; Morton, Nicol; Olivero, Davide; Daniele Tiraboschi (2009). "The Global Boundary Stratotype Section and Point (GSSP) for base of the Bathonian Stage (Middle Jurassic), Ravin du Bès Section, SE France" (PDF). Episodes. 32 (4): 222–248. doi:10.18814/epiiugs/2009/v32i4/001.
- ^ For a detailed geologic timescale, see Gradstein et al. (2004)
- ^ López, Fernández; Rafael, Sixto; Pavia, Giulio; Erba, Elisabetta; Guiomar, Myette; Paiva Henriques, María Helena; Lanza, Roberto; Mangold, Charles; Morton, Nicol; Olivero, Davide; Tiraboschi, Daniele (2009). "The Global Boundary Stratotype Section and Point (GSSP) for base of the Bathonian Stage (Middle Jurassic), Ravin du Bès Section, SE France". Episodes. 32 (4): 222–248. doi:10.18814/epiiugs/2009/v32i4/001.
- ^ a b One or more of the preceding sentences incorporates text from a publication now in the public domain: Howe, John Allen (1911). "Bathonian Series". In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 3 (11th ed.). Cambridge University Press. p. 513. That article further references A. de Lapparent, Traité de géologie (5th ed., 1906), vol ii.
Literature
[edit]- Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
- d'Omalius d'Halloy, J.B.J.; 1843: Précis élémentaire de géologie, Bertrand, Paris. (in French)
External links
[edit]- GeoWhen Database - Bathonian
- Jurassic-Cretaceous timescale, 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
