Hidden manganese compounds may have fueled Earth’s oxygen rise

hidden manganese – A new high-pressure manganese oxide found in computer simulations could help explain how Earth’s oxygen rose around the Great Oxygenation Event, and why seismic waves slow in some deep regions—though researchers say direct evidence from inside the mantle is st

Under Earth’s feet. far beyond the reach of drilling and light. manganese may exist in a form scientists have never seen. A buried. unusual compound—suggested by computer simulations of extreme pressure and heat—could have fed into one of the planet’s biggest transformations: the rise of oxygen in the atmosphere.

For hundreds of millions of years before oxygen became common, Earth’s atmosphere held little of it. Then, about 2 billion years ago, the Great Oxygenation Event began to reshape the planet. Oxygen produced by photosynthesizing microbes started to accumulate, helping set off the development of more diverse life.

Manganese sits at the center of that story in a different way. It’s thought to have been a crucial component in an early version of photosynthesis. before the oxygen-producing pathway widespread today evolved. In Earth’s crust. manganese commonly appears in oxygen-containing ores. and those ores began to accumulate around the same time as the Great Oxygenation Event.

The new work begins with a question: could at least some of those ores have originated from manganese in a form that’s been hiding deep underground?. Jingming Shi. at Jiangsu Normal University in China. and colleagues suggest that some manganese ore may have come from a manganese compound deep in Earth’s mantle that had been unknown.

Many manganese oxides are already known at normal pressure. But to understand what might survive deep inside the planet, Shi and the team examined stability under extreme conditions. They ran a computer simulation to test thousands of different arrangements of manganese and oxygen atoms. pushing pressures up to 1.5 million times atmospheric pressure—conditions comparable to roughly 2. 900 kilometres beneath Earth’s surface.

The simulations produced several new compounds, including one with four manganese atoms for every oxygen atom. That ratio is unusually metal-rich, and Shi said the surprise wasn’t just the discovery—it was the durability. “We did not necessarily expect such a manganese-rich oxide to be stable over such a wide pressure range. That was the most interesting and unexpected finding,” he said.

There’s still no direct proof that this compound exists in the mantle. But the team argues its behavior could match what geophysicists observe. Its properties might help explain why seismic waves travel unusually slowly through some regions where Earth’s mantle meets the core. If manganese-rich patches in the deep interior have been overlooked. Shi says they might also be unaccounted for in earlier work tracking how manganese moved through Earth over time.

That, in turn, feeds back into the oxygen story. Timothy Lyons. at the University of California. Riverside. said the new manganese compound could plausibly have migrated from inside Earth to the floor of ancient oceans. That movement would help explain why so much manganese ore appeared during the Great Oxygenation Event.

“It’s a potentially important piece of the manganese cycle, an element with far reaching importance from the early evolution of life to modern production of steel and batteries and human health,” Lyons said.

High pressure, researchers say, can be a kind of chemical locksmith. Caroline Peacock. at the University of Leeds in the UK. pointed out that extreme compression can stabilize compounds that wouldn’t normally form near Earth’s surface. Under such conditions, atoms bond differently, and materials can take on unfamiliar crystal structures and oxidation states.

Still. Peacock cautioned that the connections being drawn—linking the manganese simulations to seismic data. to how metals move within the mantle. and even to the Great Oxygenation Event—remain compelling but speculative. “But a lot more evidence is needed to make any firm conclusions about manganese oxides within Earth,” she said.

Shi and his colleagues are already looking for that evidence. Their next step is to study the new manganese oxide in experiments designed to mimic deep-Earth conditions. They plan to compress the material using a special instrument made from diamonds. bringing the compound under similar pressures to see whether it behaves the way the simulations suggest.

For now. the idea is both intriguing and unresolved: that a hidden. manganese-heavy oxide deep in the mantle could help knit together why oxygen surged and why the planet’s interior seems to carry distinctive clues in the way waves travel. The work doesn’t yet close the case. But it has given scientists a new candidate to chase—one that might have been out of sight during the biggest chapter in Earth’s oxygen history.

manganese oxygen Great Oxygenation Event mantle high pressure chemistry seismic waves photosynthesis manganese cycle Earth’s interior diamond anvil experiments