Australian scientists have discovered a clear link between seismic activity and the precipitation of gold and other trace elements in earthquake fault zones.
“While geochemical and geological evidence has long alluded to a connection between earthquakes and the deposition of gold, there has been much debate through the decades as to whether the precipitation of gold was a slow, equilibrium process or whether, as Professor Henley was proposing, it was a rapid and far from equilibrium process,” explained Dr Dion Weatherley from the University of Queensland’s Sustainable Minerals Institute, co-author of a study published in the journal Nature Geoscience.
The team’s mathematical model suggests that seismic activity could be one of the primary mechanisms for the formation of economical and mineable ore deposits.
“The most surprising finding we made was that even very small magnitude earthquakes of four and smaller can generate sufficient pressure reduction within fault jogs to initiate flash precipitation of gold and quartz during the earthquake itself,” Dr Weatherley said.
“While the amount of gold that would be deposited in any one earthquake is quite small, when you consider that tens or hundreds of magnitude four quakes and thousands of smaller magnitude quakes may occur each year within an earthquake fault system, the possibility exists that over time, large gold deposits may result.”
The findings challenge traditional mine geologic thinking around the formation of quartz veins under equilibrium conditions, rather suggesting a more rapid process that goes on to deposit gold in fault zones. Not surprisingly, the findings have attracted great interest from the geosciences community.
Dr Weatherley said: “we are hopeful that any deeper understanding we can gain about the physical processes that form ore bodies may help exploration geologists find new mineable gold and other mineral deposits.”
“Most of the world’s ore deposits that are exposed at the earth’s surface have either been found or already mined. Our research paper aims to reveal new findings and knowledge about the physical processes that will assist exploration geologists to discover blind ore deposits that are deeper within the Earth.”
Bibliographic information: Dion K. Weatherley & Richard W. Henley. Flash vaporization during earthquakes evidenced by gold deposits. Nature Geoscience, published online 17 March 2013; doi: 10.1038/ngeo1759
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