Earthquakes Facilitate Formation of Gold Deposits Faster Than Assumed

In a new study published in the March 17 journal Nature Geoscience said that gold deposited billions of years ago in quartz veins often exists along seismically active faults. An earthquake can shake up the rocks in these faults, sometimes pulling them apart and allowing flash vaporization to take place.

According to New Scientist, geologists have long understood that gold comes from mineral-rich, underground water networks. However, it said, this new study shows just how pressure changes initiated by earthquakes help facilitate these mineral-rich streams.

Using a model, scientists were able to determine a quantitative mechanism for the link between gold 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.

"During an earthquake, the fault jog suddenly opens wider. It's like pulling the lid off a pressure cooker: The water inside the void instantly vaporizes, flashing to steam and forcing silica, which forms the mineral quartz, and gold out of the fluids and onto nearby surfaces," explained Richard Henley, of the Australian National University in Canberra, according to NBC News.  

The fluid in the rocks can't fill gaps created so quickly, leading to dramatic, instant pressure drops, New Scientist said. The fluid therefore evaporates, leaving behind gold.

Weatherley said the amount of gold left behind after an earthquake is tiny, because underground fluids carry at most only one part per million of the precious element. However, an earthquake zone like New Zealand's Alpine Fault could build a mineable deposit in 100,000 years, Weatherley noted.