Scientists claim to have created conditions similar to a so called subduction zone. The transport and release of water during subduction processes is thought to cause volcanic – see article in Nature Geoscience (November 2017) and go to https://phys.org/print430401008.html … As a continental plate slides beneath oceanic crust (or vice versa) it moves into the Mantle – including various minerals and sediments from the ocean bottom. Over time these transform into different compounds but during the process sea water is released from the oceanic crust – inside the Mantle. Where the water seeps the temperature drops and this, it is claimed, generates magma as the rock melts which then leaks upwards to create volcanic activity. As these pressures and changes occur deep in the innards of the Earth and one cannot see them happening scientists instead, model the changes – based on rumour and hypothesis …
… in the study Kaolinite is observed changing as the subduction process is undertaken – although in this case the kaolinite was subjected to excess heat (high temperatures thought to simulate what might happen). Of course, if subduction is pie in the sky none of this research is useful – a wasted exercise in computer time. Kaolin is a clay mineral, better known as china clay. Water derived from clays and other minerals on the sea bed can produce water – inside the Mantle.