New research utilising advanced computer simulations has unveiled a previously unknown manganese compound, stable under the immense pressures and temperatures found deep within Earth's mantle. This discovery, detailed in a recent study, suggests that this compound may have played a significant, albeit hidden, role in the planet's journey towards an oxygen-rich atmosphere, a crucial development for the evolution of life as we know it.
The compound, identified as MnN4, is theorised to exist hundreds of kilometres beneath the Earth's surface. Scientists have long debated the precise mechanisms that led to the 'Great Oxidation Event' approximately 2.4 billion years ago, a period when oxygen levels in the atmosphere dramatically increased. While biological processes, particularly photosynthesis by early life forms, are widely accepted as a primary driver, geological contributions have also been a subject of intense study.
The simulations indicate that MnN4 could act as a reservoir for oxygen deep within the Earth. Under certain conditions, and through complex geological processes, this oxygen could have been released from the mantle and eventually made its way to the surface and into the atmosphere. This offers a compelling new hypothesis that complements existing theories and provides a deeper understanding of the interplay between Earth's interior and its atmospheric composition.
The research involved complex computational modelling to predict the behaviour of manganese and nitrogen atoms under the extreme conditions of the lower mantle. These conditions, characterised by pressures millions of times greater than at the Earth's surface and temperatures reaching thousands of degrees Celsius, are impossible to replicate in standard laboratory settings. The stability of MnN4 under these parameters suggests it is a viable candidate for a deep-Earth oxygen-bearing compound.
While the study presents a fascinating new perspective, researchers emphasise that these findings are based on theoretical models. Further geological and geophysical research, potentially involving seismic imaging or the analysis of deep-Earth samples if they ever become accessible, would be required to empirically confirm the existence and exact role of MnN4 in Earth's oxygenation history. Nonetheless, it opens up new avenues for understanding the fundamental processes that shaped our planet.
Source: Nature Communications