Hidden Oxygen Source Deep Inside Earth

Scientists have uncovered an unexpected oxygen storage mechanism in magma deep within Earth, revealing that molten rock can absorb significant amounts of extra oxygen under high pressure. Led by researchers including Dr. Yanhao Lin and Dr. Ho-kwang Mao from HPSTAR, alongside Prof. Haiyang Niu and Prof. Wim van Westrenen, the study published in National Science Review demonstrates that excess oxygen becomes incorporated directly into the silicate glass structure rather than remaining trapped as gas bubbles. This high-pressure oxygen uptake could mean that rising magma acts as a crucial transport mechanism, carrying oxidizing power from deep underground to the shallow mantle, crust, and atmosphere. The authors emphasize that this newly discovered non-stoichiometric oxygen behavior in silicate melts closely mirrors the pressure-dependent behavior of volatiles like water and carbon dioxide. By treating oxygen as a separate component in magma dynamics, geoscientists can fundamentally reassess planetary evolution, magma ocean development, and the historical buildup of atmospheric oxygen. This mechanism offers a compelling explanation for major increases in atmospheric oxygen that occurred roughly 2.5 to 2.0 billion years ago, which coincide with the extensive formation of large igneous provinces. The research utilized sophisticated laboratory experiments combining synthetic mid-ocean ridge basalt, platinum oxide (PtO2) as an oxygen source, and high-pressure apparatuses operating at temperatures from 1,200 to 1,800 degrees Celsius and pressures up to 7 gigapascals. Complementary atomic-level simulations using deep neural network interatomic potentials confirmed that oxygen atoms form peroxide-like bonds under high pressures. These findings bridge a major gap in understanding how Earth interior processes directly influence surface habitability and atmospheric composition. Practical implications of this study invite geoscientists and planetary researchers to incorporate high-pressure oxygen solubility into models of terrestrial planet evolution and long-term atmospheric stability. Researchers studying ancient oxidation events should factor in volcanic degassing of excess oxygen from deep mantle plumes rather than relying solely on surface biological sources like photosynthesis. This framework encourages a comprehensive re-evaluation of geological timelines and geochemical cycles across Earth history and potentially on other terrestrial planets.