Scientists at the University of Southampton in Britain have uncovered an unusual geological phenomenon that is expanding the Atlantic Ocean.
Seismologists installed 39 seismometers at the bottom of the Atlantic Ocean as part of the PI-LAB (passive mapping of the lithosphere-asthenosphere boundary) and EURO-LAB (experiment to explore the rheological boundary of the oceanic lithosphere and asthenosphere) experiments. These data represent the first large-scale high-resolution image of the mantle beneath the Mid-Atlantic Ridge.
It is known that the continental plates of North and South America are moving away from Europe and Africa at a rate of four centimeters per year. Between these continents is the Mid-Atlantic Ridge, an area of plate divergence under which magmatic melt is forced. The moving force of the Atlantic plate divergence has long been a mystery because the Atlantic Ocean is not surrounded by subduction zones, in which continental plates sink into the mantle.
Scientists were able to map changes in the structure of the Earth’s mantle near depths of 410 and 660 kilometers. This allowed them to confirm upwelling (upwelling of deep ocean waters to the surface) in the mantle from a depth of 600 kilometers. It is believed that usually upwelling under ridges occurs at much shallower depths, about 60 kilometers.