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- Geological_history_of_oxygen abstract "Before photosynthesis evolved, Earth's atmosphere had no free oxygen (O2). Oxygen was first produced by photosynthetic prokaryotic organisms that emitted O2 as a waste product. These organisms lived long before the first build-up of oxygen in the atmosphere, perhaps as early as 3.5 billion years ago. The oxygen they produced would have almost instantly been removed from the atmosphere by weathering of reduced minerals, most notably iron. This 'mass rusting' led to the deposition of banded iron formations. Oxygen only began to persist in the atmosphere in small quantities about 50 million years before the start of the Great Oxygenation Event. This mass oxygenation of the atmosphere resulted in rapid buildup of free oxygen. At current atmospheric rates, today's concentration of oxygen could be produced by photosynthesisers in 2,000 years. Of course, in the absence of plants, photosynthesis was slower in the Precambrian, and the levels of O2 attained were modest (<10% of today's) and probably fluctuated greatly; oxygen may even have disappeared from the atmosphere again around 1,900 million years ago These fluctuations in oxygen had little direct effect on life, with mass extinctions not observed until the appearance of complex life around the start of the Cambrian period, 541 million years ago. The presence of O2 provided life with new opportunities. Aerobic metabolism is more efficient than anaerobic pathways, and the presence of oxygen undoubtedly created new possibilities for life to explore.Since the start of the Cambrian period, atmospheric oxygen concentrations have fluctuated between 15% and a maximum of 35% of atmospheric volume towards the end of the Carboniferous period (about 300 million years ago), a peak which may have contributed to the large size of insects and amphibians at that time. Whilst human activities, such as the burning of fossil fuels, have an impact on relative carbon dioxide concentrations, their impact on the much larger concentration of oxygen is less significant.".
- Geological_history_of_oxygen thumbnail Oxygenation-atm-2.svg?width=300.
- Geological_history_of_oxygen wikiPageExternalLink mg20527461.100-first-breath-earths-billionyear-struggle-for-oxygen.html.
- Geological_history_of_oxygen wikiPageID "24377796".
- Geological_history_of_oxygen wikiPageRevisionID "606616146".
- Geological_history_of_oxygen date "May 2014".
- Geological_history_of_oxygen hasPhotoCollection Geological_history_of_oxygen.
- Geological_history_of_oxygen reason "undefined, unexplained".
- Geological_history_of_oxygen subject Category:Oxygen.
- Geological_history_of_oxygen comment "Before photosynthesis evolved, Earth's atmosphere had no free oxygen (O2). Oxygen was first produced by photosynthetic prokaryotic organisms that emitted O2 as a waste product. These organisms lived long before the first build-up of oxygen in the atmosphere, perhaps as early as 3.5 billion years ago. The oxygen they produced would have almost instantly been removed from the atmosphere by weathering of reduced minerals, most notably iron.".
- Geological_history_of_oxygen label "Geological history of oxygen".
- Geological_history_of_oxygen sameAs m.0118dj60.
- Geological_history_of_oxygen sameAs Q17105640.
- Geological_history_of_oxygen sameAs Q17105640.
- Geological_history_of_oxygen wasDerivedFrom Geological_history_of_oxygen?oldid=606616146.
- Geological_history_of_oxygen depiction Oxygenation-atm-2.svg.
- Geological_history_of_oxygen isPrimaryTopicOf Geological_history_of_oxygen.