A rock sample of less than 1 mm that was deformed in the middle crust of the earth. It's porosity is highlighted in red.Photo by: Dr Florian Fusseis, University of Western Australia

For the first time scientists have discovered the presence of a natural deep earth pump that is a crucial element in the formation of ore deposits and earthquakes.The process, called creep cavitation, involves fluid being pumped through pores in deformed rock in mid-crustal shear zones, which are approximately 15 km below the Earth’s surface.

The fluid transfer through the middle crust also plays a key role in tectonic plate movement and mantle degassing.The discovery was made by examining one millimetre sized cubes of exposed rock in Alice Springs, which was deformed around 320 million years ago during a period of natural mountain formation.

The evidence is described in a paper published in the latest edition of Nature entitled Creep cavitation can establish a dynamic granular fluid pump in ductile shear zones.

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