Judith Coggon at the University of Bonn, Germany, said that the first 600 million years of Earth are called the Hadean, as it was previously believed that at this period of the time, Earth was hellish and uninhabitable.
However, Coggon and her team were able to locate rocks in Greenland that had a chemical signature from the mantle about 4.1 billion years ago, which was just about 400 million years after Earth was formed.
According to models, metals like gold and platinum, which are capable of dissolving in molten iron, should have sunk into the iron-rich core as it was being formed.
And as they are relatively abundant in the mantle, scientists have theorised that meteorites and comets smashing into the planet about 3.9 billion years ago were able to replenish the stock.
This hypothesised event, now called the Late Veneer, is also believed to have given Earth most of its water, which was delivered as ice.
Coggon's rock samples suggest that our planet's mantle was already topped with iron-loving minerals like gold and platinum by 4.1 billion years ago, meaning that the Late Veneer, and the formation of Earth's oceans, may have occurred earlier that previously believed.
Coggon believes that the event may have happened before 4.3 billion years ago, as rocks from that age, which she discovered, hinted that, at the time they formed, Earth's mantle was already rich in iron-loving minerals.
Coggon said that her research has also helped push back the date for the beginning of life to have taken place on the planet.
The study has been published in Nature Geoscience.
--ANI (Posted on 31-08-2013)