Stenian
| Stenian | |
|---|---|
Period | |
| Stratigraphic unit | System |
| Time span formality | Formal |
| Lower boundary definition | Defined chronometrically |
| Lower GSSA ratified | 1991[4] |
| Upper boundary definition | Defined chronometrically |
| Upper GSSA ratified | 1991[4] |
The Stenian Period (Mya to 1000 Mya (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically. The name derives from narrow polymetamorphic belts formed over this period.
Preceded by the Ectasian Period and followed by the Neoproterozoic Era.
The supercontinent Rodinia assembled during the Stenian. It would last into the Tonian Period.
This period includes the formation of the Keweenawan Rift at about 1100 Mya.[5]
Fossils of the oldest known sexually reproducing organism, Bangiomorpha pubescens, first appeared in the Stenian.[1]
See also
- Boring Billion – Earth history, 1.8 to 0.8 billion years ago
- Riphean (stage) – stage in the geological timescale named after the Urals
Notes
- ^ doi:10.1130/G39829.1.
- ISBN 9780813712062.
- ISSN 0016-7606.
- ^ .
- ^ "Organic geochemical study of mineralization in the Keweenawan Nonesuch Formation at White Pine, Michigan" (PDF). University of Michigan. Retrieved 28 September 2011.
References
- "Stenian Period". GeoWhen Database. Archived from the original on May 12, 2006. Retrieved January 5, 2006.
- James G. Ogg (2004). "Status on Divisions of the International Geologic Time Scale". Lethaia. 37 (2): 183–199. .
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