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Earthquakes with the Midas Touch

The enormous Goldstrike pit in Nevada

The enormous Goldstrike pit in Nevada, USA, was formed about 40 million years ago, possibly due to ancient earthquakes.

By Steven Micklethwaite

Earthquakes are catastrophic events, but the stress changes they generate deep in the Earth mean they have not so much a silver lining, but a golden one.

Steven Micklethwaite is a Senior Research Fellow with the ARC Centre of Excellence in Ore Deposits at the University of Tasmania.

The full text of this article can be purchased from Informit.

Gold can be found everywhere in very small amounts. It exists as a trace element in rocks and soils; it is dissolved in seawater; and even plants have the ability to take up gold and retain it dissolved in their tissues.

But before we are tempted to dig up our gardens it is important to understand that the amounts are too small to extract and make money. Typical concentrations are just 2–3 parts per billion: that is, 2–3 grams of gold for every 1000 tonnes of garden rock.

What unique processes concentrate gold and help form mineral deposits in the first place? One answer may be as simple as the natural plumbing generated by earthquakes deep in the crust. By forming intense networks of fractures over short periods of time, earthquakes are able to focus the migration of hot, chemically-rich fluids much like a drain pipe collecting water during a downpour. Under the right conditions, these fluids will react with the rocks they are flowing through, or with other fluids that they mix with, triggering the precipitation of minerals and gold from solution.

By predicting where earthquakes are likely to generate fracturing, we have been able to test this theory and develop a novel approach to gold exploration.

Our Dynamic Earth
Earthquakes are just one form of phenomena that develop on active faults. They are seismic events...

The full text of this article can be purchased from Informit.