The Orosirian ( //; Greek: oroseira - ὀροσειρά, meaning "mountain range") is the third geologic period in the Paleoproterozoic Era and lasted from 2050 Mya to 1800 Mya (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically.
Two of the largest known impact events on Earth occurred during the Orosirian. At the very beginning of the period, 2023 Mya, a large asteroid collision created the Vredefort impact structure. The event that created the Sudbury Basin structure occurred near the end of the period, 1850 Mya.
- "Orosirian Period". GeoWhen Database. http://www.stratigraphy.org/bak/geowhen/stages/Orosirian.html. Retrieved July 8, 2011.
- James G. Ogg (2004). "Status on Divisions of the International Geologic Time Scale". Lethaia 37 (2): 183–199. doi:10.1080/00241160410006492.
Preceded by Archean Eon 2.5 Ga - Proterozoic Eon - 542 Ma Followed by Phanerozoic Eon 2.6 Ga - Paleoproterozoic Era - 1.6 Ga 1.6 Ga - Mesoproterozoic Era - 1.0 Ga 1.0 Ga - Neoproterozoic Era - 542 Ma Siderian Rhyacian Orosirian Statherian Calymmian Ectasian Stenian Tonian Cryogenian Ediacaran This geochronology article is a stub. You can help Wikipedia by expanding it.