Origin of Earth’s Oxygen

In the Neoarchean era 2.5 billion years ago oxygen was absent on earth. Do you know how we got this 25% oxygen? 

A study says the first oxygen came from the movement and destruction of the Earth’s crust. 

 2.5 billion years ago the earth was completely covered with green oceans shrouded in a methane haze and completely lacking multicellular life. 

The dominant tectonic activity is called plate tectonics, where the oceanic crust sinks into the Earth’s mantle at points of convergence called subduction zones.

One feature of modern subduction zones is their association with oxidized magmas. 

These magmas are formed when oxidized sediments & bottom water's cold, dense water near the ocean floor are introduced into the Earth’s mantle. This produces magma with high oxygen and water content.

The discovery of such magmas in Neoarchean magmatic rocks may show that plate tectonics and subduction first 

Granitoid rocks that are between 2750 and 2670 million years old were sampled by researchers from several locations in the Superior Province's Abitibi-Wawa subprovince.

The biggest intact portion of the Archean continent, spanning more than 2000 km from Winnipeg, Manitoba, to far-eastern Quebec.

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