Earthquakes Deposit Gold In Fault Zones

sciencehabit writes "Gold deposits may be created in a flash—literally. Along fault zones deep within Earth's crust, small cavities filled with fluids rich in dissolved substances such as gold and silicate minerals can expand suddenly to as much as 130,000 times their former size during a major earthquake, a new analysis suggests. In such circumstances, pressure drops accordingly, driving a process the scientists call flash evaporation. And when the pressure in the cavity suddenly drops, so does the solubility of minerals in the water there. Along with substantial quantities of quartz, large earthquakes could deposit as much as 0.1 milligrams of gold along each square meter of a fault zone's surface in just a fraction of a second Typical rates of seismicity along a fault, such as the San Andreas fault zone shown in the main image, could generate a 100-metric-ton deposit of gold in less than 100,000 years."

So how do they keep the gold from dissolving?

[khallow]

There doesn't seem to be much point to the observation since the gold can dissolve again, perhaps even within a few minutes of the end of the earthquake (it is hot down there, especially after a big earthquake).