In a ground-breaking discovery that rewrites our understanding of Earth's water composition, scientists have unearthed evidence of a colossal hidden ocean trapped within the planet's mantle. This subterranean sea, located roughly 700 kilometers beneath the Earth's surface, dwarfs all the world's surface oceans combined, containing three times their total volume.
The discovery, detailed in a 2014 scientific paper titled "Dehydration melting at the top of the lower mantle," sheds light on the origins and potential movement of water within our planet. Researchers believe this internal ocean is trapped within a specific mineral called ringwoodite, found in the mantle transition zone – a region between the upper and lower mantle. Ringwoodite's crystal structure allows it to store vast quantities of water, acting like a giant sponge within the Earth.
The existence of this hidden ocean has significant implications for our understanding of plate tectonics. The prevailing theory suggests that tectonic plates, the massive slabs that form Earth's crust, carry water down into the mantle as they subduct, or slide, beneath other plates. This newly discovered reservoir strengthens this theory, providing a potential resting point for the subducted water within the mantle transition zone.
Furthermore, the presence of such a large amount of water within the mantle could influence geological processes. Water can lower the melting point of rock, potentially playing a role in the formation of mantle plumes – giant, hot upwellings of molten rock that rise from the deep mantle and influence volcanic activity and plate movement.
The discovery of this internal ocean was made possible by analyzing seismic waves generated by earthquakes. By studying how these waves traveled through the Earth's interior, scientists were able to identify unique signatures that pointed towards the presence of large amounts of water trapped within the mantle transition zone.
This newfound knowledge of Earth's internal water composition opens doors to further research. Scientists are now eager to understand how this water interacts with the surrounding mantle rock, its influence on mantle dynamics, and its potential role in shaping our planet's geological processes over vast stretches of time. The existence of this hidden ocean redefines our understanding of Earth's water cycle, revealing a subterranean realm that holds a key to our planet's history and evolution.