A team of University of Nevada-Reno and University of Nevada-Las Vegas researchers have devised a new model for how Nevada’s gold deposits formed, which may help in exploration efforts for new gold deposits.
The deposits, known as Carlin-type gold deposits, are characterized by
extremely fine-grained nanometer-sized particles of gold adhered to pyrite over
large areas that can extend to great depths. More gold has been mined from
Carlin-type deposits in Nevada in the last 50 years – more than $200 billion
worth at today’s gold prices – than was ever mined from during the California
gold rush of the 1800s.
This current Nevada gold boom started in 1961 with the discovery of the Carlin
gold mine, near the town of Carlin, at a spot where the early westward-moving
prospectors missed the gold because it was too fine-grained to readily be seen.
Since the 1960s, geologists have found clusters of these Carlin-type deposits
throughout northern Nevada.
They constitute, after South
Africa, the second largest concentration of
gold on Earth. Despite their importance, geologists have argued for decades
about how they formed.
“Carlin-type deposits are unique to Nevada in that they represent a perfect
storm of Nevada’s ideal geology – a tectonic trigger and magmatic processes,
resulting in extremely efficient transport and deposition of gold,” says John
Muntean, a research economic geologist with the Nevada Bureau of Mines and
Geology at the University of Nevada-Reno, and previously an industry geologist
who explored for gold in Nevada for many years. “Understanding how these deposits
formed is important because most of the deposits that cropped out at the
surface have likely been found. Exploration is increasingly targeting deeper
deposits. Such risky deep exploration requires expensive
“Our model for the formation of Carlin-type deposits may not directly result in
new discoveries, but models for gold deposit formation play an important role
in how companies explore by mitigating risk. Knowing how certain types of gold
deposits form allows one to be more predictive by evaluating whether
ore-forming processes operated in the right geologic settings. This could lead
to identification of potential new areas of discovery.”
Mining Topics: New Model for Gold Exploration
March 1, 2011