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Makes about 120 million years ago, a giant bubble of molten rock flowed from the edge of the earth’s core and is directed toward the surface of the planet. And now, according to a research conducted by researchers in new zealand, a good part of that “super featherweight” has been located off the coast of New Zealand.
As explained in the study, newly published in Science Advances, scientists measured the speed of seismic waves that travel through a particular area of the earth’s mantle (between the crust and the core of the planet), known as the plateau Hikurangi. this Is a huge chunk of volcanic rock in the shape of a triangle that extends from the seafloor of the South Pacific, up to 3,200 km of depth below him, just off the coast of the North island of New Zealand. The researchers found similarities between these seismic waves and moving through two other volcanic structures nearby, suggesting that all were united in the past.
the authors of The study, therefore, believe that it is very likely that these three structures underwater to become part of a unique and huge plateau, formed over 100 million years during the highest emission of magma known in the entire history of the Earth.
New Zealand, on an ocean of lava
“The volcanic activity associated with these structures may have played an important role in the history of the Earth -says Simon Lamb, of the University of new zealand Victoria and co-author of the research, influence the climate of the planet and also in the evolution of life, to trigger episodes of mass extinction . It’s intriguing to think that, at present, New Zealand sits on what was once a ground force enormously powerful.”
According to Tim Stern, first author of the article, the feathers of the mantle are formed when huge bubbles of lava are separated from the boundary between the mantle and the outer core of the planet, rising thousands of miles to the surface. And despite the fact that most of these bubbles are trapped in the own cloak, some fragments continue to rise, melting gradually as the pressure decreases and exploding finally in the surface through volcanoes.
Since long ago, geologists suspect that the feathers of the mantle are directly responsible for the existence of some of the biggest “hot-spots” of the Earth , including the long line of volcanoes stretching from Hawaii to the Russian Pacific coast.
“is Already in the decade of the 70’s,” explains Stern – geophysicists have proposed that Earth’s mantle experienced movements and jolts, as in a lava lamp, and that made bubbles of hot rock float up like pillars from the Earth’s core toward the surface. The melting of these rocks near the surface could be the cause of intense volcanic activity, as observed in Iceland or Hawaii”.
The largest spill volcanic Earth
But the column of mantle that has accumulated in the South Pacific 120 million years ago could be, according to Stern and his team, the greatest in the entire history of our planet. The massive discharge of volcanic, continues Stern, “occurred in the southwest Pacific in the Cretaceous period, in the time of the dinosaurs, forming a volcanic plateau submarine the size of a continent. After that, the movement of the tectonic plates broke that plateau and one of its fragments, which today form the plateau Hikurangi, walked away towards the south and is now located just below the North island and also in the ocean shallow sea”.
Only the plateau Hikurangi extends over 400,000 square km, double that of the own New Zealand. And if ever you formed part, together with the plateaus, Ontong-Java and Manihiki, a “mega plateau” even more, the rocks of the three structures should have similar characteristics, both above and below the seafloor.
Checking the theory
To test this, the researchers measured the velocity of seismic waves traveling under Hikurangi. And they discovered that that move horizontally much faster (at 9 km per second) that the traveling in the vertical, towards the depths of the Earth. For Stern and his team, that difference is indicative of an old superpluma of the mantle that has begun to collapse. In addition, the strange relationship between the speeds of the waves of horizontal and vertical matched to perfection with the measures under the plateaus of Ontong-Java and Manihiki.
The three plateaus are the broken parts of one and the same superpluma, the largest found until now in the entire planet. In its original form, this ancient plateau, known as plateau, Ontong-Java-Manihiki-Hikurangi, would have covered approximately 1% of the earth’s surface, with an area equivalent, according to the study, half the size of the united States.
“it Is extraordinary -says Stern – check that all of those plateaus were connected in the past, forming the largest flow of volcanic known, in a region of more than 2,000 km in diameter.”