Early Earth’s Deep Mantle May Have Held More Water Than Previously Believed, Study Finds

Early Earth may have housed more than twice as much water as we thought, finds new research. Though it is believed that asteroids and icy comets brought most of Earth's water, new evidence suggests the planet's deep interior may have hung on to a significant amount. Experiments suggest that rocks in Earth's lower mantle might have imprisoned enough water to fill an entire ocean.

This deep reservoir could be the reason Earth hung onto enough water to become a habitable, ocean-covered world over billions of years.

Experiments Reveal Bridgmanite's Hidden Capacity

According to a Science report published on December 11, bridgmanite, one of the planet's first and most common minerals, can contain far more water than earlier measurements indicated. Scientists reported these findings in three laboratory studies that simulated the extreme heat and pressure found deep beneath Earth.

Using experiments that replicated the temperatures and pressures found in the lower mantle, they demonstrated how heat allows bridgmanite to absorb water.Bridgmanite crystallized as the Hadean Eon's magma ocean solidified, locking water in minerals; today it makes up 60 percent of Earth's mantle under high heat.

Hidden Water Reserves Inside Deep Mantle

These deep rocks were once thought to be almost dry. New evidence indicates that the deepest realm of the mantle flowed with up to 100 times more water, which was transported by tectonics and plumes and formed oceans.

Knowing how water was stored in the earliest minerals of Earth will provide important clues about the planet's long-term water cycle, experts mentioned. Some of that original water, scientists suspect, may still be lodged thousands of miles within Earth.