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.
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