One of the most important questions surrounding Earth science is about when plate tectonics began to interact, laying the groundwork for life on Earth and shaping the Earth’s surface today. Now, scientists have discovered a new hidden layer of molten rock beneath the Earth’s crust that may help explain how plate tectonics move and earthquakes occur.
The structure of the earth can be mainly divided into the crust, mantle, outer core and inner core. The huge lithosphere that constitutes the crust and upper mantle is called a plate. Below the lithosphere is the asthenosphere, which is mainly composed of solid but malleable rocks. Scientists It is believed that the plates mainly rely on these plastic rocks to slide, and their movement is related to phenomena such as earthquakes, tsunamis, and volcanic eruptions, and plate movements can also lead to the formation of new mountains and even new continents. Therefore, it is very important to study and influence various factors that affect the earth’s plate tectonic activities.
Recently, though, scientists have discovered that the top layer of the asthenosphere appears to be softer than previously suspected.
By mapping differences in seismic wave echoes through the Earth’s interior, which can provide insight into subsurface activity that drives Earth’s plate movements, the UT Austin team found that about 160 kilometers below the surface, any asthenosphere temperature above 1,450°C would cause the upper Layers of partially molten rock emerge, forming a relatively soft boundary that allows for smooth movement of the plates as they pass through the mantle.
▲ Scientists have discovered new partially molten rock layers above the asthenosphere.
But surprisingly, the melt located in the asthenosphere did not play any role.
This is the first time scientists have detected partially melted rock in the asthenosphere, but the reason why the molten rock layer is soft is not clear, and the new research shows that this layer of partially melted rock does not soften the asthenosphere or affect the flow of the mantle. Only the seismic wave is slightly weakened at the moment of passage, indicating that it has almost no role in plate tectonics, and it is also a variable that does not need to be worried about in future models of the Earth’s interior.
The researchers say the melt is weakening the rocks in the asthenosphere, but not elongating the timescales on which the weakening rocks cause a lot of strain in the asthenosphere, or that this partially molten rock layer might allow the waves to move slower, but does not make the plates move faster.
The team hopes these new findings will give us a better understanding of how the process of plate tectonics works. The new paper was published in the journal Nature Geoscience.
(Image source: Brown University)
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