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26 kwi 2018 · the great oxygenation event was caused by the evolution of photosynthesis, photosynthesis turns CO2 and water in to sugar and oxygen. so the oxygen came from CO2 and water. keep in mind CO2 levels were many many times higher (~20X) than today.
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]
When did oxygen appear in Earth's atmosphere? There's plenty we still don't know about the details. Just how much nitrogen that early mineral rain provided our planet, for example, we're not entirely sure. But some time around 4.3 billion years ago Earth's hellish conditions finally started to cool and the deluge of space rocks eased up.
1 mar 2019 · The new study published February 25, 2019 in the peer-reviewed journal Nature Geoscience, has provided evidence for significant ocean oxygenation before the GOE, on a larger scale and to...
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.
The earliest known fossil of a eukaryote—the term for organisms, from yeast to humans, that have a cell nucleus and usually require oxygen—is about 2 billion years old. The first fossil big enough to be seen without a microscope—the spiral-chained algae Grypania —appeared 1.9 billion years ago.
11 maj 2023 · At first, the oxygen produced by cyanobacteria was sequestered in minerals and seawater. But between 2.4 and 2.5 billion years ago, cyanobacteria were producing enough oxygen to be stored in Earth’s atmosphere. This time period, when oxygen levels in the atmosphere began to appreciably rise, is known as the Great Oxidation Event.
