Summary
The Floian is the second stage of the Ordovician Period. It succeeds the Tremadocian with which it forms the Lower Ordovician epoch. It precedes the Dapingian Stage of the Middle Ordovician. The Floian extended from 477.7 to 470 million years ago. The lower boundary is defined as the first appearance of the graptolite species Tetragraptus approximatus.[7]
| Floian | |||||||||||
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| 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 Graptolite Tetragraptus approximatus | ||||||||||
| Lower boundary GSSP | Diabasbrottet quarry, Västergötland, Sweden 58°21′32″N 12°30′09″E / 58.3589°N 12.5024°E | ||||||||||
| Lower GSSP ratified | 2002[5] | ||||||||||
| Upper boundary definition | FAD of the Conodont Baltoniodus triangularis | ||||||||||
| Upper boundary GSSP | Huanghuachang section, Huanghuachang, Yichang, China 30°51′38″N 111°22′26″E / 30.8605°N 111.3740°E | ||||||||||
| Upper GSSP ratified | 2007[6] | ||||||||||
Naming and history edit
The Floian Stage is named after Flo, a village in Västergötland, southern Sweden. The name "Floan" was proposed in 2004, but the International Commission on Stratigraphy adapted Floian as the official name of the stage.[8]
GSSP edit
The GSSP of the Floian is the Diabasbrottet Quarry (58°21′32″N 12°30′09″E / 58.3589°N 12.5024°E) which is an outcrop of a shale-dominated stratigraphic succession. The lower boundary of the Floian is defined as the first appearance of Tetragraptus approximatus which is above the base of the Tøyen Shale.[8] Radiometric dating has set the Tremadocian-Floian boundary at 477.7 million years ago.[9]
The upper boundary which is also the base of the Dapingian stage is defined as the first appearance of the conodont species Baltoniodus triangularis at the GSSP in the Huanghuachang Section, Hubei Province, China.[10]
References edit
- ^ Wellman, C.H.; Gray, J. (2000). "The microfossil record of early land plants". Phil. Trans. R. Soc. B. 355 (1398): 717–732. doi:10.1098/rstb.2000.0612. PMC 1692785. PMID 10905606.
- ^ Korochantseva, Ekaterina; Trieloff, Mario; Lorenz, Cyrill; Buykin, Alexey; Ivanova, Marina; Schwarz, Winfried; Hopp, Jens; Jessberger, Elmar (2007). "L-chondrite asteroid breakup tied to Ordovician meteorite shower by multiple isochron 40 Ar- 39 Ar dating". Meteoritics & Planetary Science. 42 (1): 113–130. Bibcode:2007M&PS...42..113K. doi:10.1111/j.1945-5100.2007.tb00221.x.
- ^ Lindskog, A.; Costa, M. M.; Rasmussen, C.M.Ø.; Connelly, J. N.; Eriksson, M. E. (2017-01-24). "Refined Ordovician timescale reveals no link between asteroid breakup and biodiversification". Nature Communications. 8: 14066. doi:10.1038/ncomms14066. ISSN 2041-1723. PMC 5286199. PMID 28117834.
It has been suggested that the Middle Ordovician meteorite bombardment played a crucial role in the Great Ordovician Biodiversification Event, but this study shows that the two phenomena were unrelated
- ^ "Chart/Time Scale". www.stratigraphy.org. International Commission on Stratigraphy.
- ^ Bergström, M.; Löfgren, Anita; Maletz, Jörg (December 2004). "The GSSP of the Second (Upper) Stage of the Lower Ordovician Series: Diabasbrottet at Hunneberg, Province of Västergötland, Southwestern Sweden". Episodes. 27 (4): 265–272. Retrieved 13 December 2020.
- ^ Chen, Xu; Bergström, Stig; Zhang, Yuan-Dong; Fan, Jun-Xuan (2009). "The base of the Middle Ordovician in China with special reference to the succession at Hengtang near Jiangshan, Zhejiang Province, southern China" (PDF). Lethaia. 42: 218–231. doi:10.1111/j.1502-3931.2008.00148.x. Retrieved 13 December 2020.
- ^ "GSSP for Floian Stage". Geologic TimeScale Foundation. Archived from the original on 2024-04-16.
- ^ a b Bergström, Stig M.; Anita Löfgren; Jörg Maletz (2004). "The GSSP of the Second (Upper) Stage of the Lower Ordovician Series: Diabasbrottet at Hunneberg, Province of Västergötland, Southwestern Sweden" (PDF). Episodes. 27 (4): 265–272. Retrieved 20 September 2012.
- ^ "GSSP Table - Paleozoic Era". Archived from the original on 2023-10-08.
- ^ "GSSP for Dapingian Stage". Geologic TimeScale Foundation. Archived from the original on 2024-04-04.
External links edit
- "GSSP for base of the Floian Stage in the Diabasbrottet section, Mt Hunneberg, Sweden, with stratigraphic ranges of graptolites and conodonts". timescalefoundation.org. Archived from the original on 2024-04-04.
- "GSSP Table - Paleozoic Era". Archived from the original on 2023-10-08.
- "Floian". Subcommission on Ordovician Stratigraphy. Archived from the original on 2021-06-18.