Oceanic crust may sink to Earth's core
West of Central America, scientists from the University of California at Stanta Cruz have discovered a folded piece of oceanic crust at the boundary between the mantle and the core of the Earth that submerged beneath North America about 50 million years ago.
This enabled them to prove for the first time that subducted parts of the earth's crust do not have to get stuck in the upper mantle, as previously assumed. The research team led by Alexander Hutko also found evidence of hot, chimney-like structures at the edges of the sinking section of the crust, in which the magma displaced by it rises from the mantle base.
The approximately 300 km thick rock fold extends to a depth of 2900 km and consists of the same minerals as the earth's mantle in which it sank. However, it is around 700 degrees Celsius cooler than its surroundings. Hutko and his colleagues were able to use earthquake measurements to demonstrate this enormous jump in temperature, which extends over a distance of only around 100 kilometers. From the seismic data, the scientists used complex calculation methods to generate high-resolution three-dimensional images of the bent and folded crustal lobe.
