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Earth’s interior is cooling faster than expected, according to a study, which means our planet will go dormant like Mercury and Mars sooner than previously thought.

Researchers led by ETH Zürich studied the thermal properties of bridgmanite, the main mineral that forms the boundary between the Earth’s mantle and the outer core.

The thermal conductivity of this boundary layer determines how much energy can flow from the molten iron-nickel core into the much cooler viscous mantle above it.

Using a laser in a diamond anvil press to simulate core-mantle boundary conditions, the team found that bridgmanite conducts heat 1.5 times better than previously thought.

This will likely mean that plate tectonics, which relies on heat-driven convection in the mantle, will slow down faster than previously thought.

However, it is unclear exactly how long this process will take.

Earth’s interior (pictured) is cooling faster than expected, a study has concluded, meaning our planet will go dormant like Mercury and Mars sooner than thought.

The research was carried out by Earth scientist Motohiko Murakami from ETH Zürich and his international team of colleagues.

‘Our results could offer us a new perspective on the evolution of the Earth’s dynamics,’ explains Professor Murakami.

“They suggest that Earth, like the other rocky planets Mercury and Mars, is cooling and going dormant much faster than expected.”

Estimating how much heat bridgmanite can transfer from the core to the mantle has long been a challenge, because experimental verification of the mineral’s thermal conductivity under such extreme conditions is extremely difficult.

In their study, the team employed an ‘optical absorption’ measurement system in which a single bridgmanite crystal was compressed inside a diamond anvil cell, heated with one laser, and then probed with another.

‘This measurement system allows us to show that the thermal conductivity of bridgmanite is about 1.5 times higher than assumed,’ explained Professor Murakami.

This, by extension, means that the rate at which heat escapes from the core into the mantle will also be higher than previously assumed, leading to greater convection of material within the mantle and faster cooling of the atmosphere. Earth.

This cooling rate, the researchers found, may even increase in the future.

This is because when the core-mantle boundary cools beyond a certain point, the mineral phase that is stable at this interface will change from bridgmanite to post-perovskite, which conducts heat even more efficiently than bridgmanite.

In their study, the team employed an 'optical absorption' measurement system in which a single bridgmanite crystal (right) was compressed inside a diamond anvil cell (left), heated with a laser, and then tested. with another (at the position of the red dot in the image on the right

In their study, the team employed an ‘optical absorption’ measurement system in which a single bridgmanite crystal (right) was compressed inside a diamond anvil cell (left), heated with a laser, and then tested. with another (at the position of the red dot in the image on the right

What is not clear, however, is how long it will take for conventional currents within the mantle to stop.

“We don’t yet know enough about these kinds of events to pin down their timing,” said Professor Murakami, noting that we first need a better understanding of the ways in which mantle convection works both spatially and temporally.

In addition to this, the terrestrial scientist added, we would also need to determine how the dynamics of the mantle are affected by the decay of radioactive elements in the core, which is one of the main sources of the Earth’s internal heat.

The full results of the study were published in the journal Earth and Planetary Science Letters.

The Earth moves under our feet: tectonic plates move through the mantle and produce earthquakes by rubbing against each other

The tectonic plates are made up of the Earth’s crust and the upper part of the mantle.

Beneath it is the asthenosphere: the conveyor belt of warm, viscous rock on which tectonic plates move.

Earth has fifteen tectonic plates (pictured) that together have shaped the landscape we see around us today.

Earth has fifteen tectonic plates (pictured) that together have shaped the landscape we see around us today.

Earthquakes usually occur at tectonic plate boundaries, where one plate sinks below another, pushes another up, or where plate edges scrape against each other.

Earthquakes rarely occur in the middle of plates, but they can happen when old faults or cracks deep below the surface are reactivated.

These areas are relatively weak compared to the surrounding plate and can easily slip and cause an earthquake.


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