Earth:Floian
| Floian | |
|---|---|
| 477.7 ± 1.4 – 470.0 ± 1.4 Ma | |
| Chronology | |
| 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 |
| GSSP ratified | 2002[1] |
| 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 |
| GSSP ratified | 2007[2] |
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.[3]
Naming and history
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.[4]
GSSP
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.[4] Radiometric dating has set the Tremadocian-Floian boundary at 477.7 million years ago.[3]
References
- ↑ 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. https://www.researchgate.net/publication/279891211_The_GSSP_of_the_second_Upper_stage_of_the_Lower_Ordovician_series_Diabasbrottet_at_Hunneberg_province_of_Vastergotland_southwestern_Sweden. 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". Lethaia 42: 218-231. doi:10.1111/j.1502-3931.2008.00148.x. https://stratigraphy.org/gssps/files/dapingian2.pdf. Retrieved 13 December 2020.
- ↑ 3.0 3.1 "GSSP Table - Paleozoic Era". Geologic TimeScale Foundation. https://engineering.purdue.edu/Stratigraphy/gssp/index.php?parentid=77.
- ↑ 4.0 4.1 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". Episodes 27 (4): 265–272. http://www.stratigraphy.org/GSSP/file41.pdf. Retrieved 20 September 2012.
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