Siderian Period
2500–2300 million years ago

Banded iron formations were very common in this period.

The Siderian Period (pronunciation: /sˈdɪəriən/; 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]



  1. Paleoclimates: The First Two Billion Years - James F. Kasting & Shuehi Ono, 2006
  2. The Paleoproterozoic Snowball Earth: A climate disaster triggered by the evolution of oxygenic photosynthesis - Kopp et al.

This article is issued from Wikipedia - version of the 10/22/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.