A measuring system that measures the thermal conductivity of bridgmanite in the laboratory, under the pressure and temperature conditions that prevail inside the Earth, has been developed by a team of researchers. The study has been published in the ‘Earth and Planetary Science Letters Journal’. The evolution of our Earth is the story of its cooling: 4.5 billion years ago, extreme temperatures prevailed on the surface of the young Earth, and it was covered by a deep ocean of magma. Over millions of years, the planet’s surface cooled to form a brittle crust. However, the enormous thermal energy emanating from the Earth’s interior set dynamic processes in motion, such as mantle convection, plate tectonics and volcanism. Still unanswered, though, are the questions of how fast the Earth cooled and how long it might take for this ongoing cooling to bring the aforementioned heat-driven processes to a halt.

 

One possible answer may lie in the thermal conductivity of the minerals that form the boundary between the Earth’s core and mantle. This boundary layer is relevant because it is here that the viscous rock of the Earth’s mantle is in direct contact with the hot iron-nickel melt of the planet’s outer core. The temperature gradient between the two layers is very steep, so there is potentially a lot of heat flowing here. The boundary layer is formed mainly of the mineral bridgmanite. However, researchers have a hard time estimating how much heat this mineral conducts from the Earth’s core to the mantle because experimental verification is very difficult.