The presence of minerals that are as old as three billion years in Mauritius points to the existence of a "lost continent" underneath the Indian Ocean island, says a study.
The researchers believe the lost continent was left over by the break-up of the supercontinent, Gondwana, which started about 200 million years ago.
By studying the mineral, zircon, found in rocks spewed up by lava during volcanic eruptions, the scientists concluded that remnants of this mineral were far too old to belong to the island of Mauritius.
"Earth is made up of two parts - continents, which are old, and oceans, which are 'young'. On the continents you find rocks that are over four billion years old, but you find nothing like that in the oceans, as this is where new rocks are formed," explains Lewis Ashwal from the University of the Witwatersrand in Johannesburg, South Africa.
"Mauritius is an island, and there is no rock older than nine million years old on the island. However, by studying the rocks on the island, we have found zircons that are as old as three billion years," Ashwal, lead author of a paper published in the journal Nature Communications, noted.
Zircons are minerals that occur mainly in granites from the continents.
They contain trace amounts of uranium, thorium and lead, and due to the fact that they survive geological processes very well they contain a rich record of geological processes and can be dated extremely accurately.
"The fact that we have found zircons of this age proves that there are much older crustal materials under Mauritius that could only have originated from a continent," Ashwal said.
This is not the first time that zircons that are billions of years old have been found on the island.
A study done in 2013 has found traces of the mineral in beach sand. However, this study received some criticism, including that the mineral could have been either blown in by the wind, or carried in on vehicle tyres or scientists' shoes.
"The fact that we found the ancient zircons in rock, corroborates the previous study and refutes any suggestion of wind-blown, wave-transported or pumice-rafted zircons for explaining the earlier results," Ashwal added.
There are many pieces of various sizes of "undiscovered continent", collectively called "Mauritia", spread over the Indian Ocean, left over by the breakup of Gondwanaland, Ashwal said.
--IANS
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