About 2,900 kilometers below the Earth’s surface, the core consists of an alloy of iron with nickel that was a major player in the planet’s evolution. New laboratory experiments show that it can be affected by a common phenomenon known to destroy ferrous materials – rust.
Rust, a reddish-brown product, is the result of a chemical reaction that occurs when iron is exposed to moist air or oxygenated water, which metal workers fear. The Earth’s core is made of molten iron, and new research suggests that it can also rust.
The study is published in the journal Advancing Earth and Space Science. Experience has shown that when iron encounters water vapor – such as water or in the form of minerals carrying hydroxyl at a pressure of about one million atmospheres, it forms iron peroxide with a structure similar to pyrite which indicates rust formation.
This experiment is worrisome because the applied stress matches the conditions in the deep lower mantle. The research provides new insights into the Earth’s deep layers as old theories about the region where the core meets the mantle must be reconsidered.
“This rust could explain the deep water cycle in the lower mantle and the mysterious origins of ultra-low velocity zones (ULVZs)—small, thin regions above Earth’s fluid core that significantly slow seismic waves. It can also help answer questions. about the Great Oxidation event (GOE), which marked the beginning of Earth’s oxygen-rich atmosphere some 2.5 billion to 2.3 billion years ago,” according to the report published in the journal Advancing Earth and Space Science.
This experiment is worrisome because the applied stress matches the conditions in the deep lower mantle. (representative image)
Scientists now hope they can see the situation below the surface through the giant plume that erupts from the volcano. With this new perspective, research and observations will be modified to understand changes occurring in the depths of the planet.
Of all the global boundaries on the planet, the interface between the Earth’s core and the mantle stands out because it has the greatest variability in chemical composition and physical properties. Scientists say that if rust occurs continuously in the Core-Mantle Boundary (CMB), the overhang should exhibit certain seismic signals.
Experiments show that this layer of rust causes a significant decrease in seismic wave velocity and pressure. This cutting can make primary rust recognizable if the layer of accumulated rust is three to five kilometers long.
Meanwhile, scientists have yet to determine what causes the oxygenation event that might cause rust.
While experiments suggest that the core may have corroded, it is very difficult to find concrete evidence of such an event. Scientists hope to find evidence as more research is done.
“If all the pieces of the puzzle fell into place, core rust may already be a massive internal oxygen generator on Earth — and the next atmospheric oxygenation event may be underway,” the report said.