Geochemical Environments of the Archean–Proterozoic

Resumo

In the Precambrian sequence, namely, in the Proterozoic, Archean calcium and ferruginous carbonate rocks changed to magnesian carbonate ones. This correlates with the massive development of cyanobacteria, the carbon dioxide absorption and oxygen generation of which led to a change from the Archean acidic reducing environments to alkaline oxidizing environments in the Proterozoic.