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Geological history of oxygen. Although oxygen is the most abundant element in Earth's crust, due to its high reactivity it mostly exists in compound (oxide) forms such as water, carbon dioxide, iron oxides and silicates. Before photosynthesis evolved, Earth's atmosphere had no free diatomic elemental oxygen (O 2). [2]
Today, around 21 percent of Earth's atmosphere is made up of oxygen. But our planet's atmosphere took time to develop to its current breathable state. The earliest mix of gases to form a thick layer around our cooling planet some 4.6 billion years ago wasn't much different to the kind of stuff emitted by volcanoes, such as methane, hydrogen ...
19 lut 2014 · Nature - Until about two billion years ago free oxygen was a scarce commodity in the Earth's atmosphere. For decades geochemists have been refining the story of how and when early life...
19 sie 2009 · So how did Earth end up with an atmosphere made up of roughly 21 percent of the stuff? The answer is tiny organisms known as cyanobacteria, or blue-green algae.
1 mar 2019 · Through numerous studies in this field of research, however, evidence has emerged that there were minor amounts of O2 in small areas of Earth’s ancient shallow oceans before the GOE.
11 maj 2023 · Our Sun formed about 4.57 billion years ago from a cloud of collapsing dust and gas, in an unremarkable corner of the Milky Way galaxy. The material left over the Sun’s formation coalesced into everything else in our Solar System, including Earth, which was born around 4.55 billion years ago.
1 sty 2010 · The Hadean ranges from the formation of the Earth to the first possible evidence for life, the Archean from then until the advent of atmospheric oxygen and the Proterozoic to the explosion of diverse animal forms, about 0.5 BYA.
