What do the basic composition of the planet and drip coffee have in common?

The technology developed has provided new insights into the process by which the materials that made up the Earth’s core descended into our planet’s interior, leaving behind geochemical trails that have baffled scientists for a long time.

According to the findings, published in the journal Science Advances, two Carnegie University scientists, Yingwai Fei and Lin Wang, have developed a new technique to simulate conditions in the Earth’s interior.

Earth material accumulated from a disk of dust and gas that surrounded our Sun during its youth. As the Earth grew out of smaller bodies over time, denser material sank inward, dividing the planet into distinct layers, including an iron-rich metallic core and a silicate core.

“The separation of core and core is the most important event in the geological history of the Earth. Convection in the outer core feeds the Earth’s magnetic field, protecting us from cosmic rays. Without it, life as we know it could not exist,” Fei explained. .

And each layer of our planet has its own composition. Although the core is mostly iron, seismic data shows that some of the lighter elements such as oxygen, sulfur, silicon and carbon were dissolved in it and taken on a journey towards the center of the planet. Similarly, the core is mostly silicates, but its concentrations of so-called iron-loving elements have puzzled scientists for decades.

“Understanding the mechanisms by which materials move through these layers and identifying any remnants of this process will improve our knowledge of the various ways in which the Earth’s core and core interact throughout its history,” Wang said.

In the lab, Carnegie scientists used heavy hydraulic presses, such as those used to make synthetic diamonds, to subject samples of the material to high pressure, simulating conditions in the Earth’s interior. This allowed them to recreate in miniature the process of differentiation of materials and layers of the Earth and explore various possible ways of forming the core.

Using these tools, Wang and Fei developed a new method for tracking the movement of nucleating liquid metal in samples as they move inwards.

Scientists have shown that, like water filtered through coffee grounds, under the dynamic conditions of the early Earth, molten iron could pass through gaps between layers of hard silicate crystals, called grain boundaries (in polycrystalline matter)). exchange of chemical elements.

Wang and Fey suggest that the harsh environment on the early Earth had already created conditions that would have turned the core into a giant “pouring” device (a “drip coffee” technique in which water is poured over ground coffee), which would have allowed the metal to leach out the liquid. through an interconnected network. They analyzed the chemical exchanges during this filtration process. Their results will explain the retention of iron-loving elements in the core (mantle), shedding light on a long-standing question in geochemistry.

Wang and Fey believe that their new method is generally applicable to the study of other rocky planets and may help answer other questions about the fundamental interactions that occur deep inside the core.

Source: phys.org.