A team of South African researchers have discovered traces of an ancient continent underneath Mauritius by analysing a mineral named zircon, found in rocks spewed up by lava during volcanic eruptions.
In a study published in Nature Communications, the team said that remnants of the mineral were too old to belong to Mauritius. “Mauritius is an island, and there is no rock older than 9 million years on the island,” said lead author Lewis D. Ashwal, a geoscientist at the University of the Witwatersrand in South Africa. But when studying rocks on the island, they found zircons that were 3 billion years old.
These findings apparently corroborate a study done in 2013 that found traces of ancient zircons in beach sand. Ashwal says the fact that they found the mineral in rock “refutes any suggestion of wind-blown, wave-transported or pumice-rafted zircons” demonstrating, in no uncertain terms, “the existence of ancient continental crust beneath Mauritius”.
Mauritia, as the researchers have dubbed it, was only a quarter of the size of Madagascar and has been buried under volcanic material for millions of years.
“It’s a continent in the geological sense, not in the geographical one,” Ashwal told the New York Times.
Before the continents we know today were formed, the Earth’s continental mass consisted of one gigantic continent, called Pangea. According to a paper by Ashwal and his team, the Mauritia microcontinent was part of Gondwana; an ancient supercontinent that existed 200 million years ago and, before breaking apart, contained the landmass of today’s Antarctica, South America, Africa, Madagascar and Australia, as well as the Arabian Peninsula and the Indian Subcontinent. Once Gondwana broke apart, the tectonic movement caused Mauritia to fracture and sink 84 million years ago. Underwater volcanic eruptions from the sunken continent created Mauritius, also spewing forth the ancient zircons that Ashwal collected for his paper.
The first hints of Mauritia’s existence date to 2013, when scientists uncovered variations in the gravitational pull within the Indian Ocean. Mauritius sits on one such area and scientists concluded that these differences point to the existence of an ancient continent, lost deep beneath the ocean waves.
Professor Ashwal said there are a number of pieces of “undiscovered continent” of various sizes spread over the Indian Ocean, left behind by the breakup.
“This breakup did not involve a simple splitting of the ancient super-continent of Gondwana,” says Ashwal, but “a complex splintering took place, with fragments of continental crust of variable sizes left adrift within the evolving Indian Ocean basin.”