Taking Earth's Inner Temperature

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The temperature of Earth’s interior affects everything from the movement of tectonic plates to the formation of the planet.

A new study led by Woods Hole Oceanographic Institution (WHOI) suggests the mantle—the mostly solid, rocky part of Earth’s interior that lies between its super-heated core and its outer crustal layer – may be hotter than previously believed. The new finding, published March 3 in the journal Science, could change how scientists think about many issues in Earth science including how ocean basins form.

The temperature of Earth’s interior affects everything from the movement of tectonic plates to the formation of the planet.

A new study led by Woods Hole Oceanographic Institution (WHOI) suggests the mantle—the mostly solid, rocky part of Earth’s interior that lies between its super-heated core and its outer crustal layer – may be hotter than previously believed. The new finding, published March 3 in the journal Science, could change how scientists think about many issues in Earth science including how ocean basins form.

“At mid-ocean ridges, the tectonic plates that form the seafloor gradually spread apart,” said the study’s lead author Emily Sarafian, a graduate student in the MIT-WHOI Joint Program. “Rock from the upper mantle slowly rises to fill the void between the plates, melting as the pressure decreases, then cooling and re-solidifying to form new crust along the ocean bottom. We wanted to be able to model this process, so we needed to know the temperature at which rising mantle rock starts to melt.”

But determining that temperature isn’t easy. Since it’s not possible to measure the mantle’s temperature directly, geologists have to estimate it through laboratory experiments that simulate the high pressures and temperatures inside the Earth.

Read more at Woods Hole Oceanographic Institution

Photo: In her laboratory experiments, Sarafian used a piston-cylinder apparatus—one of the machines behind her—to simulate the high pressures and temperature of the Earth’s mantle. The heavy stainless steel plates visible on the table are stacked on the apparatus, with the tiny synthetic mantle sample inside a “pressure vessel” underneath them. Once the machine is turned on, pistons apply massive pressure from above and below the sample, which is simultaneously heated with electrical current. (Photo by Veronique LaCapra, Woods Hole Oceanographic Institution)