Scientists from the Magma and Volcanoes Laboratory (CNRS) and the European Synchrotron, the ESRF, have recreated the extreme conditions 600 to 2900 km below the Earth’s surface to investigate the melting of basalt in the oceanic tectonic plates. They exposed microscopic pieces of rock to these extreme pressures and temperatures while simultaneously studying their structure with the ESRF’s extremely powerful X-ray beam.
The results show that basalt produced on the ocean floor has a melting temperature lower than the peridotite which forms the Earth’s mantle. Near the core-mantle boundary, where the temperature rises rapidly, the melting basalt produces liquids rich in silica (SiO2), which react rapidly with the mantle and indicate a speedy dissolution of the basalt back into the depths of the Earth. These experiments provide a new explanation for seismic anomalies at the base of the mantle while fixing its temperature in the region of 4000 K.
The results are published in Science on the 23 May 2014.
Read more at: Phys.org