Computer simulations have identified a previously unknown manganese-rich oxide that may have contributed to Earth's Great Oxygenation Event around 2 billion years ago.
Researchers led by Jingming Shi at Jiangsu Normal University in China used simulations to test thousands of manganese and oxygen arrangements under pressures up to 1.5 million times atmospheric levels. They identified a stable compound with four manganese atoms per oxygen atom that could exist deep in the mantle. Shi noted the unexpected stability of this manganese-rich oxide across a wide pressure range. The compound might help explain slow seismic wave speeds near the mantle-core boundary and could have supplied manganese to ancient ocean floors. Timothy Lyons of the University of California, Riverside, described it as a potentially important piece of the manganese cycle. Caroline Peacock at the University of Leeds said the connections to seismic data and the oxygenation event remain speculative and require further experimental confirmation. The findings appear in Physical Review B.