The hot, purulent center of the Earth and its cold hard outer shell are responsible for the creeping (and sometimes catastrophic) movement of tectonic plates. But now, new research is revealing an intriguing balance of powers – the sharp mantle creates supercontinents while the crust tears them apart.
To reach this conclusion about the process of plate tectonics scientists have created a new computer model of Earth with crust and mantle, considered to be a seamless system. Over time, about 60% of the tectonic motion on the surface of this virtual planet was driven by rather shallow forces – within the first 62 miles (100 kilometers) of the surface. The deep, violent convection of the mantle encouraged the others. The mantle becomes especially important when the continents collide together to form supercontinents, while the shallow forces dominate when the supercontinent disintegrates in the model.
This "virtual Earth" is the first computer model to "view" the crust and mantle as an interconnected, dynamic system, researchers reported on October 30 in the journal Science Advances . Previously, researchers would have made models of heat-driven convection in the mantle, which quite closely match the observations of the true mantle but do not mimic the crust. And the models of plate tectonics in the crust might predict real-world observations of how these plates move, but they do not correlate well with mantle observations. Clearly, something was missing in the way the models put the two systems together.
Related: In photos: The ocean hidden beneath the surface of the earth but not the mantle, "said Nicola Coltis, a graduate student at Ecole Normale Supérieure, part of the PSL University in Paris." And the whole story behind the evolution of the system is the feedback between the two. "
Cortex plus mantle
Each model of the Inner Earth classes shows a thin layer of crust that rides on top of it This simplified model may give the impression that the crust is simply surfing the mantle, moving in this way from the unexplained currents.
But this is not entirely correct. that the crust and the mantle are part of the same system; they are inevitably connected. ”This understanding raised the question of whether the forces of the surface — such as the absorption of one short crust beneath another — or the forces deep within the mantle, predominantly drive the motion of the crust-forming plates. The answer found by Coltis and his colleagues is that the question is wrong. This is because the two layers are so intertwined, and both contribute.
Over the last two decades, Coltis told Live Science, researchers have been working on computer models that could represent the interactions between the crust and the mantle realistically. In the early 2000s, some scientists developed patterns of motion (convection) driven by heat in the mantle, which naturally gave rise to something resembling plate tectonics on the surface. But these models were laborious and did not receive much follow-up work, Coltis said.
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Coltis and his colleagues have been working on their new version of models for eight years. The simulation itself took 9 months.
Building a Model Earth
Coltis and his team first had to create a virtual Earth full of realistic parameters: everything from heat flow to the size of tectonic plates to the length of time it typically takes for the supercontinent to form and separate.
There are many ways in which the model is not a perfect imitation of the Earth, Coltis said. For example, the program does not track previous rock deformity, so rocks that have deformed before are not prone to warp more easily in their model in the future than might happen in real life. But the model still produced a realistic-looking virtual planet full of subduction zones continental drift and ocean ridges and trenches.
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Beyond showing that mantle forces dominate when continents gather, researchers find that hot circles Magma, called mantle plums, is not the main reason for continents to disintegrate. The areas of subduction in which one piece of crust is forced under another are the engines of continental decay, Coltis said. Mantle plums come into play later. Prior growing pluses may reach surface rocks that have been weakened by forces created in the subduction zones. They are then insinuated into these weaker places, making the supercontinent more likely to disintegrate at this location.
The next step, Coltis said, is to connect the model and the real world with observations. In the future, he said, the model could be used to explore everything from major events in volcanism to how plate boundaries are formed to how the mantle moves in relation to Earth's rotation.
Originally published by Live Science .