Gold has been delivered to Earth by meteorites


13/09/2011

Scientists came to the conclusion that the Earth was enriched with precious metals in clashes with meteorites.

The Earth’s crust and mantle contain much more gold than would be expected in accordance with the existing models of planet formation.

Researchers at Bristol University have analyzed some of the oldest rocks on Earth and have come to the conclusion that gold has been brought to Earth long before their formation.

The study was published in the journal Nature.

During the formation of the Earth, the iron has gone to the center of the planet, forming the core.

Any precious metals on the planet would have to go along with the iron and concentrate in the core, leaving the mantle without elements such as gold, platinum and osmium.

But as we can see, that did not happen. Quite the contrary - in the silicate mantle contains 1000 times more gold than you would expect.

It has already been proposed several theories that can explain this phenomenon, including the theory of gold hit us with meteorites. But until now, it was impossible to check.

Earth was formed like a snowball, in a process known as accretion (the fall of matter from outer space), about 4.55 billion years ago. Shortly after that, only a few million years, formed an iron core with a touch of precious metals.

Subsequent collision with a body the size of Mars, broke away from the Earth and the Moon has completed the formation of our planet. By this time, all of the gold would have to be in the nucleus.

Around 3.9 billion years ago there was a large meteorite bombardment, which caused the appearance of craters on the moon.

It was during this meteor shower on Earth was delivered gold, which we extract from the earth’s crust.

Then hit the Earth 20 billion billion tonnes of asteroidal material, although "it remains unclear whether this was in the form of a series of minor collisions or only two or three major mega-collision" - said the lead researcher, Matthias Uillbold.

Original: Bbc


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