We might finally know how ocean-sized deposits of water hundreds of kilometres below Earth’s surface are getting there: a spongy sort of clay that is bringing it underground
We might finally know how ocean-sized deposits of water hundreds of kilometres below Earth’s surface are getting there. A form of clay, called kaolinite, might be soaking up water like a sponge and bringing it deep underground.
Depending on the location, kaolinite accounts for between 5 and 60 per cent of ocean sediment . Now, geologists have demonstrated how it can act as an irrigation system for the upper mantle, the mineral and rock layer that descends to more than 400 kilometres beneath our feet.
The clay gets sucked down underground when an oceanic plate collides with the continental crust and nosedives beneath it in a process called subduction, reaching depths sometimes deeper than the upper mantle after millions of years.
Lab experiments simulating the escalating pressures and temperatures encountered during the descent have now shown for