For 150 million years before the “revolution”, the planet experienced one such crash that ended after a few million years.
Ancient rock age of about 2.45 billion years contain traces of the oxygen catastrophe of global climate change. It is believed that they are associated with the occurrence of photosynthesis, which led to the emergence of free oxygen, which changed the face of the planet. However, for the hundreds of billions of years before this event, the oxygen level on Earth has been raised and dropped again. This group of professors of the University of Washington Roger Buick (Roger Buick) writes in an article published in the journal PNAS, informs Rus.Media.
“The process of formation and decay of oxygen molecules in the oceans and the atmosphere for a long time was like a war with no obvious winner until the oxygen catastrophe, says one of the authors Matt Koehler (Matt Koehler). — These interim disaster was a battle in the war, and gradually the balance has shifted toward oxygenation”. Indeed, in 2007, Roger Buick colleagues showed that sediment on the continental shelf of Western Australia contain traces of “intermediate oxygen catastrophe” that occurred 50 million years before the main.
In his new work, the team of Professor Buick describes another story, Dating back 100 millions of years before — about of 2.66 billion years ago and has gone through several tens of millions of years. This was indicated by the analysis of isotopes of nitrogen and selenium contained in the rocks of the formation Gera (Jeerinah) in the same Western Australia. Extracted from the shallow seabed cores show gradual change in the content of these elements and their back — related changes with the appearance and disappearance of the oxygen.
The fact that the exact isotopic composition of atoms of nitrogen in ancient sediments depends on the activity of microorganisms that use it for synthesis of nitrates, and the nitrates for energy. This process requires free oxygen, so that nitrogen is able to say about its presence in the surface layers of the ocean. Selenium also is contained in sulfide minerals from the land, and the increase of oxygen in the atmosphere leads to their oxidation and leaching of selenium into the sea, where it accumulates and the more oxygen in the air.
“If you will not be able to detect oxygen in the atmosphere of a distant planet, it does not mean that there is no life or even fotosinteticos life — adds Roger Buick. — Maybe life’s just not powerful enough source of free oxygen that can permanently “to overcome the” binding mechanisms”.