|2500 – 2300 Ma|
A Siderian banded iron formation in Dales Gorge, Western Australia
Artist's impression of the Earth during the Huronian glaciation, starting from mid-Siderian
|Proposed redefinition(s)||2630–2420 Ma|
Gradstein et al.
Gradstein et al.
|Regional usage||Global (ICS)|
|Time scale(s) used||ICS Time Scale|
|Time span formality||Formal|
|Lower boundary definition||Defined Chronometrically|
|Lower boundary GSSP||N/A|
|Upper boundary definition||Defined Chronometrically|
|Upper boundary GSSP||N/A|
The Siderian Period ( //; Ancient Greek:, 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 deposition of banded iron formations peaked early in this period. These iron rich formations were formed as anaerobic cyanobacteria produced waste oxygen that combined with iron, forming magnetite (Fe3O4, an iron oxide). This process removed iron from the Earth's oceans, presumably turning greenish seas clear. Eventually, with no remaining iron in the oceans to serve as an oxygen sink, the process allowed the buildup of an oxygen-rich atmosphere. This second, follow-on event is known as the oxygen catastrophe, which, some geologists believe triggered the Huronian glaciation.
Since the time period from 2420 Ma to 2250 Ma is well-defined by the lower edge of iron-deposition layers, an alternative period named the Oxygenian, based on stratigraphy instead of chronometry, was suggested in 2012 in a geological timescale review.
- Kasting, James F.; Ono, Shuehi (2006). "Paleoclimates: The First Two Billion Years". Philosophical Transactions: Biological Sciences 361 (1470): 917–929. doi:10.1098/rstb.2006.1839. PMID 16754607.
- Kopp, Robert E.; Kirschvink, Joseph L.; Hilburn, Isaac A.; Nash, Cody Z. (2005). "The Paleoproterozoic Snowball Earth: A climate disaster triggered by the evolution of oxygenic photosynthesis". PNAS 102 (32): 11131–11136. doi:10.1073/pnas.0504878102. PMID 16061801. PMC 1183582. http://authors.library.caltech.edu/1015/1/KOPpnas05.pdf.
- Gradstein, F. M., ed (2012). The Geologic Time Scale 2012. 1. Elsevier. pp. 361–365. ISBN 978-0-44-459390-0.
- "Siderian Period". GeoWhen Database. http://www.stratigraphy.org/upload/bak/geowhen/stages/Siderian.html.
- "The Siderian". Dinosaurfact.net. Retrieved May 24, 2015.
Original source: https://en.wikipedia.org/wiki/ Siderian. Read more