London: The gold and platinum that we see on Earth today may have come from outer space following a mammoth meteorite shower more than four billion years ago, scientists have claimed.

Geologists at the University of Bristol also discovered that there is enough gold and platinum in the Earth's core to plate the surface of the globe with a layer of priceless bling four metres thick.

It is believed that huge deposits of gold and other precious metals appeared during the Earth's formation moved into the planet's core when molten iron sank to its centre.

This left the Earth lacking gold and platinum until a cataclysmic meteor shower bombarded the earth 200 million years later, they researchers said.

During the 200-million-year-long shower, a staggering 20 quintillion tonnes of meteorite matter, including gold and platinum, slammed into the earth, the Daily Mail reported.

This mammoth meteorite shower, the researchers believe, replenished the earth's lost reserves of precious metals.

"Our work shows that most of the precious metals on which our economies and many key industrial processes are based have been added to our planet by lucky coincidence when the Earth was hit by about 20 billion billion tonnes of asteroidal material," said Dr Matthias Willbold, who led the research.

The researchers wanted to know how there is enough gold and platinum deposits on Earth which is believed to have lost all its precious metals during its formation.

To help resolve this, they examined ancient rocks found from Greenland to see how the planet changed over time. Their analysis revealed that they were formed at the time of Earth's formation and contained a marginally higher ratio of the tungsten isotope 182W compared to more modern rock.

Therefore, modern rock must have come from a meteorite shower which proves today's gold and platinum deposits came from outer space, the researchers said. Dr Willbold said, "Extracting tungsten from the rock samples and analysing its isotopic composition to the precision required was extremely demanding given the small amount of tungsten available in rocks.

"In fact, we are the first laboratory world-wide that has successfully made such high-quality measurements."

The metals from these earth-shattering meteorites were stirred into the planet's mantle by gigantic convection processes, the researchers reported in the journal Nature.

These later emerged in newly formed continents, concentrated in the ore deposits which are mined today, they added.