Oxygenation of the Earth’s Atmosphere
Earth’s oxygenation is an increase in the concentration of atmospheric molecular oxygen (O2) from levels of less than 1 ppmv before 2.45 Ga to 21 % by volume today. Larger amounts of atmospheric oxygen became possible because of shifts in the competition between the production of oxygen derived from photosynthesis and the rate of consumption of oxygen by different geological processes. Evidence from ancient rocks suggests that oxygenation happened in steps, with a first rise of O2 at 2.45–2.32 Ga and a second around 0.75–0.58 Ga. The latter increase was a precursor to the appearance of macroscopic animals.
The present atmosphere contains (by volume) 78.05 % N2, 20.95 % O2, 0.93 % Ar, 0.038 % CO2, and various trace gases. With the exception of argon, the concentrations of all of the major gases are biologically modulated. Oxygen, in particular, is almost solely biogenic because it has no significant abiotic source....
KeywordsRise of oxygen Oxygenation
References and Further Reading
- Catling DC, Kasting JF (2016) Atmospheric evolution on inhabited and lifeless words. Cambridge University Press, Cambridge in pressGoogle Scholar
- Holland HD (1984) The chemical evolution of the atmosphere and oceans. Princeton University Press, PrincetonGoogle Scholar
- Knoll AH (2003) Life on a young planet: the first three billion years of evolution on Earth. Princeton University Press, PrincetonGoogle Scholar
- Sakurai R, Ito M, Ueno Y, Kitajima K, Maruyama S (2005) Facies architecture and sequence-stratigraphic features of the Tumbiana formation in the Pilbara Craton, northwestern Australia: implications for depositional environments of oxygenic stromatolites during the Late Archean. Precambrian Res 138:255–273CrossRefGoogle Scholar
- Walker JCG (1986) Earth history: the several ages of the Earth. Jones and Bartlett, BostonGoogle Scholar