Scientists have discovered a vast underground reservoir of water deep within Earth's mantle, challenging previous assumptions about the planet's water cycle. This hidden ocean, located approximately 700 kilometers beneath the surface, is contained within a mineral called ringwoodite, which can trap water molecules within its crystal structure. The discovery suggests that Earth's mantle may hold more water than all surface oceans combined, offering new insights into the planet's geological processes and the origin of its water.
The research team, led by geophysicist Steven Jacobsen, utilized seismic data from thousands of earthquakes to detect water-rich rocks deep beneath the surface. By analyzing how seismic waves traveled through the Earth, they identified regions where the waves slowed down, indicating the presence of water. This method provided evidence of a substantial water reservoir within the mantle's transition zone, a layer between the upper and lower mantle.
Ringwoodite, a high-pressure form of the mineral olivine, is abundant in the transition zone. Under extreme conditions, it can incorporate water into its crystal structure, forming hydroxide ions. Laboratory experiments have shown that ringwoodite can contain up to 2.6 weight percent water, suggesting that the mantle's transition zone could store significant amounts of water. This finding has implications for understanding Earth's water cycle, plate tectonics, and volcanic activity.
The discovery also raises questions about the origin of Earth's water. While some theories propose that water arrived from icy comets, the presence of substantial water within the mantle suggests that it may have originated from within the planet itself. This internal water reservoir could have played a crucial role in the development of Earth's oceans and the emergence of life.
Further research is needed to explore the extent of this underground ocean and its impact on Earth's geological and hydrological systems. The findings open new avenues for studying the deep Earth's composition and the dynamic processes that shape our planet.