Iron Formations as Palaeoenvironmental Archives

Download or read book Iron Formations as Palaeoenvironmental Archives written by Kaarel Mänd and published by Cambridge University Press. This book was released on 2022-01-20 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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. As many iron formations are pure chemical sediments that reflect the composition of the waters from which they precipitated, they can also serve as nuanced geochemical archives for the study of ancient marine temperatures, redox states, and elemental cycling, if proper care is taken to understand their sedimentological context.