José Manuel NievesSEGUIRMadrid Updated: Save Send news by mail electrónicoTu name *
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it Is more than obvious that the ground on which we stand is solid. But the earth’s crust is like the hard shell of an egg, and under it, just a few km of depth, is the earth’s mantle, the huge layer of molten rock 3,000 km thick. The more superficial part of the mantle, which is “glued” to the bark, is still relatively strong, and together with the actual earth’s crust forms what geologists know as the lithosphere.
however, and unlike an eggshell, the lithosphere is not “all of a piece”, but that is made up of seven large fragments (tectonic plates) that move, collide, overlap or rub against each other continuously. And also by a whole constellation of fragments, or plates, much smaller. The plate tectonics , a theory that describes how they move and interact with all those fragments, you have approximately fifty years, but in all this time has not managed to understand how they developed the system, which changes continuously the shape and position of the continents on which we live. The question, therefore, is the following: How and why the “shell” of the solid Earth was divided into separate plates that began to move?
Now, an international team of researchers just published in Nature Communications, a study venture a possible explanation. During its early times, the Earth was a big ball of molten rock that is kept warm by the frequent impacts with other bodies in the young, chaotic, and violent Solar System. But with time, inevitably, began to cool. As is logical, with the outside cooled first, forming a solid crust over the mantle cast. There is some consensus among scientists about this scenario, according to which, at first, the bark was all of a piece (such as the shell of the egg), and the robe was at least some hundreds of degrees hotter than the current one. But why is this “shell” cracked and finally broken into pieces?
to try To find out, the researchers used several computer simulations. In them they saw what is what happens if, after solidifying, the crust will heat again, causing it to expand and fracturara. Each of the simulations explored what kind of deformation would suffer from the cortex to expand in several different scenarios.
The results showed that the “shell-solid” might be able to support up to a km of expansions before fracture, which would then inevitably the current system of moving plates.
past Research already showed that a volcanic activity enough you could create a cooling effect on the Earth’s surface, similar to a radiator that expels steam. As the molten rock outside coming to the surface through volcanoes, would grow cold and would sink after and into the depths. And in doing so, would grow cold lithosphere primitive planet.
But something else happened. The lithosphere is cooler, and therefore more robust, would lock the convective heat of the core below it. And that heat would have done that the lithosphere began to expand, causing cracking. In this way, and in a short time, we found ourselves with the tectonic plates.
the conclusions of their article, the researchers write, “our models show how a system of tectonic plates can evolve from processes at the surface. (… ). The onset of plate tectonics requires that the radial expansion is large enough to induce stresses horizontal that exceed the strength of the lithosphere at some time in the Eon Arcáico”.
The researchers, of course, continue to work. Their intention is to continue to develop theories that explain the complex geological processes of the Earth. “Together,” write the scientists – these studies will end up with one of the biggest mysteries of planetary science: How and why the Earth became a molten ball to be our planet divided into plates current?”.
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