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Aalenian
| Aalenian | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 The Aalenian GSSP in Spain | |||||||||
| 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 Ammonites Leioceras opalinum and Leioceras lineatum | ||||||||
| Lower boundary GSSP | Fuentelsaz, Spain 41°10′15″N 1°50′00″W / 41.1708°N 1.8333°W | ||||||||
| Lower GSSP ratified | 2000[2] | ||||||||
| Upper boundary definition | FAD of the Ammonites Hyperlioceras mundum, Hyperlioceras furcatum, Braunsina aspera, and Braunsina elegantula | ||||||||
| Upper boundary GSSP | Cabo Mondego, Portugal 40°11′57″N 8°54′15″W / 40.1992°N 8.9042°W | ||||||||
| Upper GSSP ratified | 1996[3] | ||||||||
The Aalenian ( /ɑːˈliːniən/) is a subdivision of the Middle Jurassic Epoch/Series of the geologic timescale that extends from about 174.7 ±0.8 Ma to about 170.9 ±0.8 Ma (million years ago). It was preceded by the Toarcian and succeeded by the Bajocian.[4]
- ^ "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. September 2023. Retrieved December 16, 2024.
- ^ Cresta, S.; Goy, A.; Arias, C.; Barrón, E.; Bernad, J.; Canales, M.; García-Joral, F.; García-Romero, E; Gialanella, P.; Gómez, J.; González, J.; Herrero, C.; Martínez2, G.; Osete, M.; Perilli, N.; Villalaín, J. (September 2001). "The Global Boundary Stratotype Section and Point (GSSP) of the Toarcian-Aalenian Boundary (Lower-Middle Jurassic)" (PDF). Episodes. 24 (3): 166–175. doi:10.18814/epiiugs/2001/v24i3/003. Retrieved 13 December 2020.
{{cite journal}}: CS1 maint: numeric names: authors list (link) - ^ Pavia, G.; Enay, R. (March 1997). "Definition of the Aalenian-Bajocian Stage boundary". Episodes. 20 (1): 16–22. doi:10.18814/epiiugs/1997/v20i1/004. Retrieved 23 December 2020.
- ^ See Gradstein et al. (2004) for a detailed version of the geologic timescale
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