Researchers have detected a previously unknown layer of molten rock beneath the Earth’s crust. The discovery could help scientists understand more about the movements of Earth’s tectonic plates.
The newly discovered molten layer is located 161 kilometers below the Earth’s surface. This layer is part of the asthenosphere which lies beneath the tectonic plates. The asthenosphere is a soft layer of solid but malleable rock that can cause the tectonic plates to move and shift.
Researchers have wondered what makes the asthenosphere soft and considered molten rocks to be part of the equation.
Scientists had previously spotted this newly discovered rock layer and thought it to be an anomaly, but Junlin Hua at the University of Texas at Austin and his fellow researchers found evidence that it had a broader presence. They confirmed that the asthenosphere is composed of both solid and melted rock.
“When we think about something melting, we intuitively think that the melt must play a big role in the material’s viscosity,” said Hua. “But what we found is that even where the melt fraction is quite high, its effect on mantle flow is very minor.”
“This study is fundamental to understanding why the asthenosphere — the weak mantle layer below the tectonic plates that enables the plates to move — is in fact weak,” explained study coauthor Karen M. Fischer
“Ultimately, it provides evidence that other factors such as temperature and pressure variations can control the strength of the asthenosphere and make it weak enough for plate tectonics to be possible.”
The findings of the study can help researchers understand how different layers beneath the Earth function.
https://edition.cnn.com/2023/02/07/world/earth-new-molten-rock-layer-scn