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Oxygen of tectonic origin is a new source of oxygen in our atmosphere.

Oxygen of tectonic origin is a new source of oxygen in our atmosphere.

The abundance of oxygen in our atmosphere is a vital and major reason for the survival of life on Earth's surface, but this has not always been the case. Earlier in the life of our planet, oxygen was unavailable and may not exist, and scientists are still trying to find out the main source of its presence in our atmosphere.

new possibility

New research published in Nature Geoscience suggests that the primary source of some atmospheric oxygen early in Earth's life is the movement of tectonic plates, which causes cracking and interference of the Earth's crust layers.
Research by geosciences researchers from the American University of Michigan, the Canadian University of Lorentian and China's Peking University, is based on measuring the level of oxidation of magma generated during the Neoarchean era, where oxygen was absent in the Earth's atmosphere, which may be evidence of tectonic movement at that time in Earth's lifetime.

Oxidized magma

In the foreword to their research, researchers state that oxidized magma is formed when oxidized deposits and bottom water (cold and dense water near the ocean floor) enter the Earth's scarf as a result of the movement of tectonic plates and the occurrence of subduction, where the oceanic crust - the outer layer of the Earth under the oceans - sinks into the Earth's scarf; It is the area between the Earth's crust and its pulp, at confluence points called subduction zones, which produces magma with a high oxygen and water content.

Researchers say in an article published on The Conversation that the team collected samples from granite rocks 2750 to 2670 million years old from across the Superior Province, the largest preserved continent spanning more than 2,000 kilometers from Winnipeg Manitoba to the far east of Quebec Province in Canada.

Sulfur measurement in zircon crystals

Researchers say that measuring the oxidation status of these volcanic rocks formed by cooling and crystallizing magma or lava is difficult, because these rocks may have encountered post-crystallization events, causing changes through distortion, burial or heating.

Because zircon stones have the potential to withstand extreme temperatures and the pressures of post-crystallization events, researchers decided to scrutinize the abatite metal found in zircon crystals in the rock samples they collected, because they may contain evidence about the environments in which they were originally formed, and can infer precise ages of the rocks themselves.
Using specialized techniques to measure sulfur in the original magma, the researchers found a marked increase in sulfur presence in approximately 2705 million years. Furthermore, a predominance of "+ S6" - one of the sulfur ions - was found in the apatite metal, indicating that sulfur was from an oxidizing source, which matched data from host zircon stones.

Sulphur-rich magma

In their foreword, researchers state that the findings indicate that although concentrations of marine sulfate and limited oxidizing change on the ocean floor decreased before the oxidation event about 2.4 billion years ago, sulfur-rich oxidizing magma formed in degradation zones independent of the oxidation state of the ocean, and could affect the evolution of the oceans, atmosphere and metals in modern times.

The researchers conclude from these findings that the oxygen in magma came from another source and was eventually released into the atmosphere during volcanic eruptions, Although the mechanism is not precisely clear, the presence of this oxidizing magma indicates that the process of subduction where ocean waters are transported for hundreds of kilometres within our planet generates free oxygen, which then leads to the oxidation of the upper mantle.


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