(ORDO NEWS) — An international group of scientists have proposed a new hypothesis for the appearance of oxygen on Earth, an alternative to the Great Oxidation Event hypothesis.
The increase in oxygen concentration was a slow process occurring between 2.8 and 1.8 billion years ago, according to the researchers’ findings, published in the journal Geosystems and Geoenvironment.
According to the Great Oxidative Event hypothesis, oxygen increased rapidly around 2.4 billion years ago and then dropped sharply over the next 200 million years.
However, analyzes of the chemical composition of minerals formed in rocks and on the seafloor have shown that the rise in atmospheric oxygen has been occurring over a billion years, with a peak of about 21 percent oxygen occurring about 1.9 billion years ago.
The slow increase in concentration is associated with the collision of continental plates, leading to the formation of supercontinents, and the evolution of cyanobacteria in the oceans.
The change in the chemical composition of minerals in the earth’s crust correlates with an increase in oxygen levels due to the presence of new types of oxidized metals, which became available only due to an increase in oxygen levels.
The increase in oxygen was also accompanied by a decrease in carbon dioxide and methane, leading to more life-friendly conditions in the ocean and atmosphere.
Prior to this, the ancient oceans were enriched with toxic elements such as arsenic and mercury. During the collision of the continents, mountain building occurred, which contributed to the leaching of nutrients into the oceans, stimulating the reproduction of microorganisms and increasing the biogenic production of oxygen.
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