Global 3D map indicates presence of water in certain areas of Earth's mantle
Washington, August 20 (ANI): Scientists from Oregon State University in the US have created the first global three-dimensional map of electrical conductivity in the Earth's mantle, which suggests that that enhanced conductivity in certain areas of the mantle may signal the presence of water.
According to scientists, those areas of high conductivity coincide with subduction zones - where tectonic plates are being subducted beneath the Earth's crust.
Subducting plates are comparatively colder than surrounding mantle materials and thus should be less conductive.
The answer, the researchers suggest, may be that conductivity in those areas is enhanced by water drawn downward during the subduction process.
"Many earth scientists have thought that tectonic plates are not likely to carry much if any water deep into the Earth's mantle when they are being subducted," said Adam Schultz, a professor in the College of Oceanic and Atmospheric Sciences at Oregon State.
"Most evidence suggests that subducting rocks initially hold water within their minerals, but that water is released as the rocks heat up," he added.
"There may be other explanations, but the model clearly shows a close association between subduction zones and high conductivity and the simplest explanation is water," he explained.
The scientists conducted their study using electromagnetic induction sounding of the Earth's mantle.
This electromagnetic imaging method is very sensitive to interconnecting pockets of fluid that may be found within rocks and minerals that enhance conductivity.
Using magnetic observations from more than 100 observatories dating back to the 1980s, they were able to create a global three-dimensional map of mantle conductivity.
The study is important because it provides new insights into the fundamental ways in which the planet works.
The implications are myriad.
Water interacts with minerals differently at different depths, and small amounts of water can change the physical properties of rocks, alter the viscosity of materials in the mantle, assist in the formation of rising plumes of melted rock and ultimately affect what comes out on the surface.
"In fact, we don't really know how much water there is on Earth," said Gary Egbert, also a professor of oceanography at OSU and co-author on the study.
"There is some evidence that there is many times more water below the ocean floor than there is in all the oceans of the world combined. Our results may shed some light on this question," he added. (ANI)