New Scientist
Image: Fragile Oasis
Even oceans can catch lethal infections. The dying Mediterranean Sea may have contaminated the Atlantic with a subduction zone. One day, it could help destroy the vast ocean.
Oceans come and go over hundreds of millions of years. New ones are bornwhen continents are ripped apart, allowing hot magma to bubble up and solidify into oceanic crust. They die when continents collide and force oceanic crust back down into the mantle.
An enduring geological mystery, though, is how the ocean-swallowingsubduction zones form in the first place. Oceanic crust cools and becomes more dense as it ages, so older crust may spontaneously buckle, sink into the mantle and form a subduction zone. But older crust is also stronger and more rigid – features that should prevent it either buckling or subducting.
To get to the bottom of this puzzle we need to find a subduction zone that is still forming, says João Duarte at Monash University in Melbourne, Australia. Now he and his colleagues may have found this missing piece of plate tectonics evidence in the oceanic crust off south-west Portugal. Read more on newscientist.com…
