Earth May Have Made its Own Oceans from Within
Scientists have long wondered how our planet came to be covered 70 percent by ocean, and now a new study has found that Earth may have made its own water from within.
The conventional theory is that our Blue Planet was once dry and hospitable, that is until icy comets from the far reaches of the solar system collided with us, depositing water on the surface. Now, researchers at The Ohio State University are suggesting that a series of geologic processes at the Earth's interior, in addition to these icy comets, helped create our water.
"When we look into the origins of water on Earth, what we're really asking is, why are we so different than all the other planets?" researcher Wendy Panero said in a statement. "In this solar system, Earth is unique because we have liquid water on the surface. We're also the only planet with active plate tectonics. Maybe this water in the mantle is key to plate tectonics, and that's part of what makes Earth habitable."
According to the study, Earth can actually form entire oceans of water from within (for billions of years) and release small amounts to the surface via plate tectonics - a phenomenon that was previously unknown to scientists.
The key to their findings is the idea that your everyday rocks actually contain water - despite appearing dry to the layman's eyes - in the form of hydrogen atoms trapped inside natural voids and crystal defects. All minerals contain oxygen, and sometimes hydrogen, so it's possible that certain chemical reactions can cause the two elements to bond and form water. And considering that Earth's mantle makes up more than 80 percent of the planet's total volume, each rock containing some hydrogen, it suggests that Earth has the potential to make enough water to fill entire oceans.
After lab tests compressed different minerals found in the mantle to assess their capacity for storing hydrogen, the researchers found potential candidates in ringwoodite, found 325-500 miles below the surface in the Earth's "transition zone," and garnet. However, the mechanics of how these minerals would release oceans of water to the surface without draining its reserves requires further study. Not to mention that the complex relationship between plate tectonics and surface water "one of the great mysteries in the geosciences," Panero added.
Despite certain discrepancies, the idea that Earth's mantle could make our own water via plate tectonics and geochemistry puts us one step closer to figuring out just how the world's oceans got here.
The findings were recently submitted to a peer-reviewed academic journal, and presented at the American Geophysical Union (AGU) meeting on Dec. 17.
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