VITALS VOLCANOES

VITALS VOLCANOES

Levels of oxygen in Earth’s atmosphere rose to a high only 2.4 billion years ago, known as the Great Oxidation Event 

Published in Nature Communications finds that understanding volcanic activity is key and that the mantle’s evolution could possibly control that of life

Great Oxidation Event (GOE): A time period when the Earth's atmosphere and the shallow ocean experienced a rise in oxygen

GEO also called the Great Oxygenation Event, Oxygen Catastrophe, Oxygen Crisis, Oxygen Holocaust,  or Oxygen Revolution

Approximately 2.4 billion years ago during the Paleoproterozoic era

Geological, isotopic, and chemical evidence suggests that biologically produced molecular oxygen started to accumulate in Earth's atmosphere and changed Earth's atmosphere from a weakly reducing atmosphere to an oxidizing atmosphere

A chronology of oxygen accumulation suggests that free oxygen was first produced by prokaryotic and then later by eukaryotic organisms in the ocean

These organisms carried out photosynthesis more efficiently, producing oxygen as a waste product

The cyanobacteria producing the oxygen caused the event which enabled the subsequent development of multicellular forms

In one interpretation, the first oxygen-producing cyanobacteria could have arisen before the GOE

However, oxygenic photosynthesis also produces organic carbon that must be segregated from oxygen to allow oxygen accumulation in the surface environment, otherwise the oxygen back-reacts with the organic carbon and does not accumulate 

Stromatolites provide some of the fossil evidence of oxygen, and suggest that the oxygen came from photosynthesis 

The burial of organic carbon, sulfide, and minerals containing ferrous iron (Fe²⁺) is a primary factor in oxygen accumulation 

The rate of change of oxygen can be calculated from the difference between global sources and sinks.

The concentration of ferruginous and euxinic states in iron mass can also provide clues of the oxygen level in the atmosphere

Some elements in marine sediments are sensitive to different levels of oxygen in the environment such as transition metals molybdenum and rhenium. Non-metal elements such as selenium and iodine are also indicators of oxygen levels

GEO triggered an explosive growth in the diversity of minerals

Most of these new minerals were formed as hydrated and oxidized forms due to dynamic mantle and crust processes