Quakes can turn water into gold?
Midas touch! Earthquakes cause water in faults to vaporise, depositing gold in the Earth’s crust, according to a new study.
The study, published in the journal Nature Geoscience, provides a quantitative mechanism for the link between the precious metal and quartz seen in many of the world’s gold deposits, said Dion Weatherley, a geophysicist at the University of Queensland in Australia and lead author of the study.
When an earthquake strikes, it moves along a rupture in the ground — a fracture called a fault.
Big faults can have many small fractures along their length, connected by jogs that appear as rectangular voids.
Water often lubricates faults, filling in fractures and jogs.
About 10 kilometres below the surface, under incredible temperatures and pressures, the water carries high concentrations of carbon dioxide, silica and economically attractive elements like gold, OurAmazingPlanet reported.
During an earthquake, the fault jog suddenly opens wider.
The water inside the void instantly vaporises, flashing to steam and forcing silica, which forms the mineral quartz, and gold out of the fluids and onto nearby surfaces, suggested Weatherley and co-author Richard Henley, of the Australian National University in Canberra.
Previously, scientists suspected fluids would effervesce, bubbling like an opened soda bottle, during earthquakes or other pressure changes.
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