Iron Formations as Palaeoenvironmental Archives

Ancient iron formations - iron and silica-rich chemical sedimentary rocks that formed throughout the Precambrian eons - provide a significant part of the evidence for the modern scientific understanding of palaeoenvironmental conditions in Archaean (4.0–2.5 billion years ago) and Proterozoic (2.5–0.539 billion years ago) times. Despite controversies regarding their formation mechanisms, iron formations are a testament to the influence of the Precambrian biosphere on early ocean chemistry. A...