Well-traveled rock – Wissenschaft.de

(Bild: Cornell University)

The photo shows cooled lava that was found in Costa Rica. It is astonishing that it bears the geochemical fingerprint of the earth’s mantle under the Galápagos Islands about 1,400 kilometers away.

Anyone who finds rock in cold lava springs in western Panama and Costa Rica and analyzes the geochemical composition, expects that it is the work of plate tectonics. Because there the coconut plate dips under the Caribbean plate and thus feeds the Central American volcanic arc. But researchers at Cornell University in New York State have made a surprising discovery: They found rock samples that must have come deep from the earth’s mantle. This can be recognized by the ratio of two helium isotopes – it is different for rocks that have formed in the earth’s interior than for rocks from the surface.

“You can think of the Earth’s mantle as an ocean with different currents,” explains Esteban Gazel, Professor of Earth and Atmospheric Sciences at Cornell University. “There are these incredibly deep currents that go all the way up from the boundary between the Earth’s core and the Earth’s mantle. We have shown that once this material has reached the upper mantle, it can spread and affect a much larger area than previously thought. “

The rock material from Costa Rica apparently comes from the mantle of the Earth under the Galápagos Islands, around 1400 kilometers away. The findings of the research team confirm the assumption that so-called mantle plumes – currents of hot rock material deep from the earth’s mantle – not only rise straight up, but also cover large stretches sideways. The scientists now want to research how far these currents can expand and thus learn more about the complex geological processes in the earth’s mantle.


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