How does iron formation form

With my help the students identify the key components to include in their sketch such as the presence versus absence or paucity of free oxygen abundant iron and continental red beds. From this exercise the students conclude that: 1. This BIF story also serves as an introduction to the topic of the origin of life on Earth including the importance of photosynthesizing cyanobacteria in oxygenation of the early atmosphere.

Even though this more-or-less standard approach to teaching about BIFs makes for a nice story I am concerned that it might represent a gross oversimplification. After all BIFs are one of the least understood and most controversial deposits on Earth.

Their temporal distribution is more complicated than stated above: for example BIFs first appeared about 3. The process of iron deposition in the Proterozoic seas, 2. It was the emergence of the earliest forms of life, tiny microbes cyanobacteria that produced oxygen through photosynthesis, that probably saw the composition of the early atmosphere begin to change.

Along with banded iron formations , the rocks of the Pilbara region also contain fossilised remnants of marine communities stromatolites built up by cyanobacteria at this time.

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