Study Reveals Complexity of Earth’s Mantle

A mineral map of a cumulate mineral sample. (Sarah Lambart / University of Utah)

(CN) – While the Earth’s mantle has never been explored directly, scientists in a study released Monday said their research has given us a better idea of what it looks like – a Jackson Pollock painting.

“If you look at a painting from Jackson Pollock, you have a lot of different colors,” said Sarah Lambart, study lead and assistant professor of geology at the University of Utah. “Those colors represent different mantle components and the lines are magmas produced by these components and transported to the surface. You look at the yellow line, it’s not going to mix much with the red or black.”

The study, published in scientific journal Nature Geoscience, portrays the mantle as a “geochemically diverse mosaic” made up of a canvas of various rocks that coexist without mixing together until they form channels of magma that push to the surface.

Scientists on the study wanted to determine what the mantle looks like before it rose as lava at a mid-ocean ridge, an underwater range of mountains. The study team looked at cores drilled through the ocean’s crust to see the first minerals in magma to crystallize.

“We looked at the most primitive part of these minerals,” Lambart said, adding that they analyzed only the chemical composition from those very earliest minerals to form. “If you are not actually looking at the most primitive part you might lose the signal of this first melt that has been delivered to the crust. That is the originality of our work.”

What the team found was a large amount of variations in isotopes of neodymium and strontium, which showed the scientists different chemistries of mantle material from various types of rock.

According to the study team, the findings show that the mantle is analogous to a blender full of separate ingredients. The various rocks are separate until the “Earth turns on the blender.” The resulting channels of magma then travel toward the mid-ocean ridge like “streaks of paint on a Jackson Pollock painting.”

Lambart said the findings could help scientists better understand exactly how material moves from the mantle to the surface of the Earth.

“The problem is we need to find a way to model the geodynamic earth, including plate tectonics, to actually reproduce what is recorded in the rock today,” she says. “So far this link is missing.”

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