It’s A Young World After All… It’s A Young, Young World

By simulating the Earth’s core conditions, researchers have shown that the core could be younger than 0.7 billion years old.

AsianScientist (Jun. 10, 2016) – Through electrical resistivity experiments, scientists in Japan have shown that the inner core of the Earth is younger than previously thought.

Their results, published in Nature, support recent theoretical studies suggesting that the Earth’s inner core is less than 0.7 billion years old.

The interior of the Earth is made up of concentric layers of solid and liquid material. The center comprises the liquid outer core, which generates the Earth’s magnetic field, and an inner core, thought to be made of solid iron mixed with traces of other lighter elements. Verifying the exact details of Earth’s inner core formation is challenging, as the conditions at the core are incredibly difficult to replicate in the laboratory.

Corresponding author Dr. Kenji Ohta from the Tokyo Institute of Technology, in collaboration with researchers from across Japan, have succeeded at measuring the electrical resistivity of solid iron at high pressures and temperatures similar to those found at the Earth’s core.

They measured the electrical resistivity of solid iron in a laser-heated diamond-anvil cell, and took measurements at temperatures in the range of 300-4,500 Kelvin, and at pressures of up to 212 gigapascals—the high end of both scales representing the Earth’s core conditions. Their experiments revealed that iron resistivity is significantly suppressed at high temperatures by what is called the resistivity saturation effect.

“The low electrical resistivity of iron indicates the high thermal conductivity of the Earth’s core, suggesting rapid core cooling and a young inner core less than 0.7 billion years old,” said Ohta.

“Therefore, an abrupt increase in palaeomagnetic field intensity around 1.3 billion years ago may not be related to the birth of the inner core.”

The article can be found at: Ohta et al. (2016) Experimental Determination of the Electrical Resistivity of Iron at Earth’s Core Conditions.


Source: Tokyo Institute of Technology; Photo: Shutterstock.
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