Iron Oxyhydroxides Could Explain Water Storage in Earth's Deep Interior

Scientists discovered iron oxyhydroxide minerals stable at the extreme pressures and temperatures found at Earth's core-mantle boundary that can store water at concentrations up to 15% by weight. These newly identified minerals may represent a crucial mechanism for how water is stored in Earth's deep mantle and transported to upper layers, influencing mantle dynamics and volcanic processes. The quantity of water in such minerals could theoretically be sufficient to account for ocean formation in the early Earth.

Earth's mantle contains water, but scientists have long debated its origin and storage mechanisms. This discovery of iron oxyhydroxide minerals addresses a significant gap in understanding mantle hydration. These minerals remain stable under the extreme conditions present where Earth's core meets the mantle—pressures exceeding one million times surface atmospheric pressure. Their capacity to hold water at such depths suggests a previously unknown reservoir that could preserve primordial water from Earth's formation.

The water content in these minerals has profound implications for planetary dynamics. Because water makes rock more pliable, it enables mantle convection and plate tectonics. The quantity of water theoretically stored in these minerals during Earth's early history could have supplied enough water to form the oceans, potentially resolving how our planet acquired its vast water systems.