A few areas of the earth are remarkably rich in certain metals and minerals. Nevada and South Africa come to mind for gold, Chile comes to mind for copper, and the Democratic Republic of Congo for copper and certain energy metals. Perhaps none of these areas, though, is as remarkable a storehouse of mineral wealth as British Columbia’s Golden Triangle with its tremendous concentration of rich gold, silver, and copper deposits.
What is it that makes the Golden Triangle stand out from other mineral districts?
Like many of the mineralized districts down the west coast of the Americas and around the Pacific Rim, the Golden Triangle is associated with a process that geologists call “subduction”: One plate of the earth’s crust is pushed under another, usually an oceanic plate being pushed under a continental plate. As the subducting plate sinks and gets deeper, the leading edge melts to form magma which is naturally buoyant and so rises toward the surface. This hot molten rock drives super-heated water, termed hydrothermal activity, which moves metals around and forms the orebodies.
In the Golden Triangle, at least three rather unique geological conditions led to a “turbo-charging” of this basic ore forming process. First, around 200 million years ago, “competing” subduction zones within what is now the Golden Triangle led to an extensional stress on the earth’s crust in that region. This extension created deep-seated faults which enhanced heat and fluid flow and gave added vigor to the hydrothermal systems.
Second, some mineralized areas of the Golden Triangle have been re-subducted and re-melted more than once, likely becoming more enriched with each episode. This process has been described as being akin to multiple distillations of a quality spirit – it becomes purer and richer with each cycle.
A third factor is that the process remained active for much longer than in other areas, continually recharging the hydrothermal system with multiple pulses of magma.
As geological research continues on the Golden Triangle, we will understand better the reasons why it is so richly endowed with metals. In the meantime, geologists are focused on exploring and creating wealth from this unique metal endowment created by a confluence of geologic events.
