Oxygen present in atmosphere much earlier than previously assumed
|Researchers analysed the oldest Banded Iron Formations (BIFs) on Earth – samples|
of marine sediments from Western Greenland [Credit: University of Copenhagen]
An international team of researchers led by Professor Robert Frei from the Department of Geoscience and Natural Resource Management at the University of Copenhagen has just released a study, published in Scientific Reports, indicating evidence for the presence of small concentrations of oxygen on Earth already 3.8 billion years ago.
The researchers analysed Earth's oldest Banded Iron Formations (BIFs) from Western Greenland. BIFs are marine chemical sediments originally composed of alternating layers of silica and Fe-hydroxides and are widely used as geochemical archives. The reason for this is that they retain information on the composition and presence of oxygenation/reduction processes in ambient seawater and on the interaction of the atmosphere with Earth's surface.
Robert Frei preparing for isotope analyses in the laboratory at the |
Department of Geosciences and Natural Resource Management,
University of Copenhagen [Credit: Kent Pørksen]
The fact that the analyses of the BIF layers from Western Greenland show elements that require presence of oxygen in the atmosphere opens up for the possibility of evolution of the earliest primitive photosynthetic life forms as early as 3.8 billion years ago.
As Robert Frei explains: "It is generally believed that the Early Earth was a completely anoxic, but our study shows that the surface of the Earth was exposed to a low oxygen atmosphere already this time. This has far reaching implications for how we investigate the pace of evolution of life and its biodiversity on our planet."
Source: Faculty of Science - University of Copenhagen [February 16, 2016]