Siderian
The Siderian Period ( /saɪˈdɪəriən/; Greek: sideros, meaning "iron") is the first geologic period in the Paleoproterozoic Era and lasted from 2500 Ma to 2300 Ma (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically.
The laying down of the banded iron formations (BIFs) peaked early this period. BIFs were formed as anaerobic algae produced waste oxygen that combined with iron, forming magnetite (Fe3O4, an iron oxide). This process cleared iron from the oceans, presumably turning greenish seas clear. Eventually, without an oxygen sink in the oceans, the process allowed the build up of an oxygen-rich atmosphere. This event is known as the oxygen catastrophe, which according to some geologists triggered the Huronian glaciation.[1][2]
References
- "Siderian Period". GeoWhen Database. Retrieved May 24, 2015.
- "The Siderian". Dinosaurfact.net. Retrieved May 24, 2015.
Notes
- ^ Paleoclimates: The First Two Billion Years - James F. Kasting & Shuehi Ono, 2006 http://www.jstor.org/stable/20209693
- ^ The Paleoproterozoic Snowball Earth: A climate disaster triggered by the evolution of oxygenic photosynthesis - Kopp et al. http://www.pnas.org/content/102/32/11131.full.pdf+html
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