The structures of the continuous size that stands out from the lower mantle to the outer core of the earth may be contributing to a Instability of the magnetic field of our planet.
The two strange formations, one under the Pacific and the other under Africa, resemble each other in terms of seismic waves, so they were supposed to have the same composition.
The Geodynamist of the University of Cardiff, James Panton, and his colleagues have concluded otherwise, determine that the two regions are made of different materials and have different stories. If it is true, it could affect the heat flow and the deep convection of our planet in a way that could influence The way the earth generates its magnetosphere.
Up to 900 kilometers (560 miles) high and thousands of kilometers wide, the two “large provinces of low speed” have baffled scientists since they were revealed by seismic data in the 1980s. The investigation has since suggested They are at least, partly, composed of the old oceanic crust.
“It is … fascinating to see the links between the movements of the plates on the surface of the Earth and structures of 3000 kilometers deep on our planet.” says The seismologist at the University of Oxford, Paula Koelemeijer.
Millions of natural cortex cycling years mixed what was once the surface of the earth in the mantle. The resulting composition now covers up to 30 percent of the nucleus, slowing down the seismic waves that geologists use to investigate the internal structure of the earth.
“Our models of circulation of the mantle in the last billion years demonstrate that the large low -speed provinces can naturally develop as a result of the recycling of the oceanic crust.” write Panton and the team, arguing against competitive theories that anomalies emerged from collision with the Earth about 4.5 billion years ago that led to the formation of the moon.
The Pacific structure seems to have 50 more fresh oceanic cortex mixed through it than the African province, the researchers found. That makes a greater difference in the composition between the Pacific province and the surrounding mantle, not to mention a notable difference in its density.
“We find that the Pacific Grandeja Province is enriched in the subduced oceanic cortex, which implies that the recent history of land subduction is promoting this difference.” says Panton.
The notoriously active Pacific Fire Ring has constantly recover the material of the cortex, the team suspects.
In contrast, the region around the African structure is not so geologically active, so the oldest cortex has been mixed more thoroughly, which makes this structure less dense.
“The fact that these two large provinces of low speed differ in composition, but not in temperature is key to history and explains why they seem to be the same seismically.” Explain Koelemeijer.
The different temperatures of these two structures, compared to their surrounding regions, affect the way heat dissipates the nucleus of the Earth, which in turn affects the convection in the nucleus that drives the magnetic field of our planet.
The researchers suspect that, as the two mantle structures do not allow the heat of the nucleus to escape uniformly on both sides of our planet, they may be contributing to unbalance the field that Maintain the life support qualities of our atmosphere.
The Great Province of low speed of Africa has already been involved in the weakening of the nearby magnetic field.
Researchers require more data, such as observations from the land gravitational field, to better understand the impacts of this asymmetry of deep land.
This research was posted in Scientific reports.
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