We’ve learned about far-flung places in the universe, but we may have just barely scratched the surface of places deep within our planet. As a result, there is a lot of information that we seem to be missing. For example, the effect that two large blocks of rock have on the Earth’s magnetic field.
in natural earth science In a paper published yesterday, researchers announced that they have found evidence of a huge clump of solid, superheated material that appears to have shaped Earth’s magnetic field for millions of years. These large lower mantle basement structures, or blobs for short, lie at the bottom of the Earth’s mantle about 1,864 miles (3,000 kilometers) below the surface of Africa and the Pacific Ocean, study lead author Andrew Biggin explained in the paper’s commentary. conversation.
Continental-sized masses are much hotter than the lower mantle, creating large temperature gradients in the rocky mantle. This sharp contrast helps keep Earth’s fluid outer core flowing, said Begin, a geologist at the University of Liverpool in the UK. earth dynamo.
“Without this massive internal heat transfer from the core to the mantle and ultimately through the crust to the surface, Earth would be like its nearest neighbors Mars and Venus: magnetically dead,” Begin writes.
history of geomagnetism
The Earth’s magnetic field is powered by the Earth’s dynamo, an electric current generated by the motion of extremely hot iron and nickel. To study historical trends in the Earth’s magnetic field, researchers look at: magnetic recording Found in rocks and other natural materials. For example, igneous rocks that result from cooled magma acquire a permanent magnetism that captures the direction of the Earth’s magnetic field at the time and place of cooling.
While studying such rocks, Biggin and his colleagues noticed distinct patterns in the rocks’ magnetic records dating back up to 250 million years. Specifically, the magnetic direction showed a strong correlation with the longitude and latitude of where the rocks were thought to have formed.
Meanwhile, in recent decades, geologists and seismologists have increasingly focused on blobs. closely related to a volcanic eruption. But Begin’s team wondered whether the various pieces of the puzzle – the magnetic records of volcanic rocks and clumps and volcanic eruptions – could explain the clumps’ role in Earth’s magnetic field.
Explore the Earth from the bottom side up
For the new study, the team developed advanced simulations that map the Earth’s magnetic field based on different thermal profiles in the core, mantle, and blob. After several attempts, the map that most accurately depicts Earth’s actual magnetic field represents a model that includes strong fluctuations in heat transfer, as can occur if a blob is actively stirring between the outer core and lower mantle.
Furthermore, the team found that certain parts of the magnetic field remain stagnant for hundreds of millions of years, and that the presence of blobs contributes to the overall stability of the magnetic field.
“What seems to be happening is that the two hot masses insulate the liquid metal below, preventing heat loss that would cause the fluid to thermally contract and sink into the core,” Begin explained.
That said, blobs remain a common mystery to scientists. Researchers have not yet properly characterized their true origin and identity. But if the simulations are correct, Begin said, “we have a lot to thank the Blob for,” as it appears to play a big role in making sure Earth keeps things going.