Welcome back my fellow learners, today we are going to learn about the connection between earthquakes and gold formations.
Scientists have known for some time that reams of gold were created by mineral deposits emanating from hot fluids which seeped through cracks in Earth’s crust. However, a study in Nature Geoscience1 found this process could happen nearly instantaneously, maybe as fast as a few tenths of a second.
This process happens along fault jogs, which as sideways zigzagged cracks which connect main fault lines in rock, so says author Dion Weatherley, who is a seismologist in the University of Queensland, Australia.
When earthquakes happen, the sides of these fault lines slide along the direction of a fault, thus rubbing against one another. However, the fault jogs just open. Weatherley and geochemist Richard Henley who is his co-author, contemplated what happened to fluids which circulated through these jogs when an earthquake happened.
What their calculations showed was surprising, a fast depressurization which sees normal high-pressure conditions, drop to pressures close to the surface.
Gradually, more fluid spews out of the rocks surrounding the gap, thus restoring the original pressure. However, this doesn’t happen immediately, and in the meantime a single earthquake will produce an instant vein of gold.
Obviously, the bigger the earthquake, the bigger the gold-vein formation. More interestingly, Weatherley and Henley discovered that even smaller earthquakes will create surprisingly large pressure drops on the fault jogs.
So there you have it folks, now we know how veins of gold are created, however, to find those that have several veins, will take many many years to create.