Frasnian
| Frasnian | |
|---|---|
Age | |
| Stratigraphic unit | Stage |
| Time span formality | Formal |
| Lower boundary definition | FAD of the conodont Ancyrodella rotundiloba |
| Lower boundary GSSP | Col du Puech de la Suque, Montagne Noire, France 43°30′12″N 3°05′12″E / 43.5032°N 3.0868°E |
| Lower GSSP ratified | 1986[5] |
| Upper boundary definition | FAD of the conodont Palmatolepis triangularis LAD of the Coumiac quarry, Montagne Noire, France 43°27′41″N 3°02′25″E / 43.4613°N 3.0403°E |
| Upper GSSP ratified | 1993[6] |
The Frasnian is one of two
Major reef-building was under way during the Frasnian Stage, particularly in western Canada and Australia. On land, the first forests were taking shape. In North America, the Antler orogeny peaked, which were contemporary with the Bretonic phase of the Variscan orogeny in Europe.
The Frasnian coincides with the second half of the "charcoal gap" in the fossil record, a time when atmospheric oxygen levels were below 13 percent, the minimum necessary to sustain wildfires.[7]
North American subdivisions of the Frasnian include
- West Falls Group
- Sonyea Group
- Genesee Group
Name and definition
The Frasnian Stage was proposed in 1879 by French geologist Jules Gosselet and was accepted for the lower stage of the Upper Devonian by the Subcommission on Devonian Stratigraphy in 1981.[8] It is named after the village of Frasnes-lez-Couvin in Belgium.[9]
References
- .
- doi:10.1086/421077.
- .
- ^ "Chart/Time Scale". www.stratigraphy.org. International Commission on Stratigraphy.
- . Retrieved 19 December 2020.
- ^ Klapper, G.; Feist, R.; Becker, R.; House, M. (December 1993). "Definition of the Frasnian/Famennian Stage boundary". 16 (4): 433–441. Retrieved 19 December 2020.
{{cite journal}}: Cite journal requires|journal=(help) - ISBN 978-0-231-16057-5. Retrieved 21 April 2015.
- ^ Coen-Aubert, Marie; Boulvain, Frédéric (2006). "Frasnian". Geologica Belgica. 9 (1–2): 19–25. Retrieved 10 March 2013.[permanent dead link]
- ^ "Frasnian mudmounds from Belgium". University of Liège. Archived from the original on 2011-07-06. Retrieved 2011-02-25.
43°30′12″N 3°05′12″E / 43.5032°N 3.0868°E
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