Mining Topics: New Model for Gold Exploration
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 drilling.
“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.”
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 drilling.
“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.”
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