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26 March 2013

Berita Semasa 26 Mac 2013 ...




Is Gold a byproduct of earthquakes?


The gold is formed when a tremor splits open a fluid-filled cavity in the crust, causing a sudden drop in pressure, they added.














Gold could be the result of repeated earthquakes, according to a study published in the journal Nature Geoscience.
A group of Australian scientists said solid gold can be deposited in the Earth’s crust almost instantaneously during earthquakes.
The gold is formed when a tremor splits open a fluid-filled cavity in the crust, causing a sudden drop in pressure, they added.
This causes the fluid to expand rapidly and evaporate, and any gold particles that had been dissolved in it to “precipitate almost immediately,” said the team.
“Repeated earthquakes could therefore lead to the buildup of economic-grade gold deposits.” they said.
The researchers said much of the world’s known gold was derived from quartz veins that were formed during geological periods of mountain building as much as 3 billion years ago.
The veins formed during earthquakes, but the magnitude of pressure fluctuations or how they drove gold mineralization were not known.
For this study, researchers used a numerical model to simulate the drop in pressure in a fluid-filled fault cavity during an earthquake.
In so doing, they answered a long-standing question about the world’s gold resources — how the metal becomes so concentrated from a highly dissolved state to a solid, mineable one.
The study said single tremors would not generate economically viable gold deposits, which were built up one thin coating at a time. Forming a 100-ton gold vein deposit would take less than 100,000 years, the team wrote.

Sumber : Google

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