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New Research Suggests Earth's Mantle Might Be Hotter Than Anyone Expected (sciencealert.com)
schwit1 quotes a report from ScienceAlert: New data suggests that the upper parts of Earth's mantle are around 60C (108F) hotter than previously expected. The mantle is the layer between our planet's super-hot core and outer crust, and it plays an incredibly important role in things like earthquakes, volcanic eruptions, and tectonic shifts. But despite the impact the mantle has on our planet, scientists have always struggled to pinpoint its temperature, and new research suggests our previous estimates were off the mark. If the new estimates made by scientists at the Carnegie Institution of Science in Washington DC are verified, it would mean the mantle is melting shallower than previously expected, and it could change the way we predict earthquakes and volcanic eruptions. The new estimates are based on the fact that the Earth's upper mantle is more affected by the presence of water in its minerals than we've assumed in the past. One of the most common ways to measure the temperature of the upper mantle is to analyze lava emerging from mid-ocean ridges - an underwater mountain range where two plates meet and hot mantle is drawn up and partially melts. So to more accurately measure the temperature at which this would melt, the researchers, led by Emily Sarafian, have used a new technique to add a quantifiable amount of water into mantle samples through tiny particles of the mineral olivine. This allowed them to more accurately measure the melting point of peridotite under mantle-like pressures in the presence of known amounts of water. "Small amounts of water have a big effect on melting temperature, and this is the first time experiments have ever been conducted to determine precisely how the mantle's melting temperature depends on such small amounts of water," said one of the researchers, Erik Hauri. They found that the potential temperature of the mantle beneath the oceanic crust is on average around 60C higher than previous estimates - with some parts much hotter than that. "Our experimental results indicate that mantle potential temperatures along all ocean spreading centers are hotter than existing estimates," the team writes in Science.