American scientists have announced that volcanic eruptions on ancient Earth are associated with an increase in the amount of oxygen in the air. The research article was published in the journal Proceedings of the National Academy of Sciences.
Oxygen is an active chemical element that almost always tends to oxidize the surrounding substances. Therefore, astrobiologists believe that a large amount of oxygen in the planet's atmosphere indicates the presence of life, since cyanobacteria and plants absorb carbon dioxide and produce oxygen.
In addition, free oxygen should not be in the depths of the earth's interior, where high temperatures are especially conducive to oxidation. However, in a new study, scientists from the University of Michigan found that volcanoes began to actively erupt on Earth several million years before the sharp increase in the mass of atmospheric oxygen.
Geologists analyzed rock samples from Australia that are 2.5 billion years old. "We found an anomalous presence of mercury: firstly, there is too much of it in the stone, and secondly, its isotopic composition indicates volcanic origin," says Roger Buick, co-author of the study.
Scientists suggest that the substances ejected during the eruption of the rock contained a large amount of chemical elements. Gradually, they were washed away by rains and weathered, turning into a breeding ground for blue-green algae and other unicellular organisms. Phosphorus was supposed to play the main role in this. “There are other nutrients that are beneficial for biological activity, but in the long term, it is phosphorus that is most important,” the authors conclude.
