Scientists say rocks from Greenland prove that precious metals, such as gold, were deposited in the Earth’s crust by asteroid showers billions of years ago.
The researchers from the University of Bristol in the UK say their experiments with material from Isua, southwest Greenland, provide evidence of a meteor bombardment some 3.9 billion years ago which laced the planet’s crust with tons of dead-star residues, forming gold, platinum, nickel and tungsten.
Rocks were sampled from before and after the suspected meteor shower, with those from the later layer found to have liquid, rather than solid, surfaces. Different concentrations of tungsten between the different rock ages also suggest that the heavy metals which we now mine arrived sometime between 4.8 billion and 3.8 billion years ago.
Research leader Matthew Willbold told Discovery that the Greenland rocks provided, “a sort of time capsule that gave us the possibility to calculate how much material had to be added to the Earth to satisfy the tungsten isotopic composition that we find in the Earth today.”
He added in the study, published in the Nature journal, that he believes around 300 billion tons (1.5 percent of the Earth’s mantle today) arrived in the form of meteors.
(Photo: Anders Peter Amsnæs)
Um, golden shower means something else in English, might want to Google that one.
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