Mauritius is hiding a lost continent underneath itself, says a team of researchers whose paper has been published in the journal Nature Communications.
Lost World in the Indian Ocean—A Piece of Gondwana
The existence of a lost continent in the Indian Ocean, lying beneath the volcanic island of Mauritius, has been confirmed by a group of researchers. The mysterious land (a piece of crust, actually) is said to have broken off the ancient supercontinent Gondwana some 200 million years ago.
Gondwana used to consist of all the continents that we know—at a time when Africa, South America, Antarctica, part of Asia (India), and Australia were together as one large land. However, time led to its split-up because of the continuous movement of the ocean basin that would shift plates of the ocean floor, and massive chunks of the big land flew away from each other. It appears, now, that a piece of the crust of Gondwana remained in the Indian Ocean, breaking off from Madagascar, after Africa, India, Australia, and Antarctia gave way to the ocean; it was eventually covered with lava released from volcanic eruptions on Mauritius. Such is the hypothesis of the researchers behind the new findings.
“We are studying the break-up process of the continents, in order to understand the geological history of the planet,” says lead author of the paper, geologist Lewis Ashwal from the University of the Witwatersrand (Wits).
Young Mauritius & Old Minerals
The study is based on the dating of the mineral zircon spotted in Mauritian rocks that were brought to the surface from volcanoes onto the island. Zircons contain invaluable information because they are resilient to time: geological processes do not cause them to become lost easily, and as the minerals survive, they can provide considerable data about geology; moreover, their dating can be done quite accurately. The remnants of the zircons found in Mauritius were deemed to be too old to belong to the island—the latter is around 9-million-years of age, and the rocks are thought to be around 6 million years old, while the mineral left-overs are 3 billion years old.
Ashwal says that continents are old, and can thus contain rocks of more than 4 billion years of age. Oceans, on the other hand, are young, and only have newly-formed rocks (on the geological timescale, that is). As for Mauritius, it will, obviously, have rocks no older than 9 million years old, and the zircons are so much older.
“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,” says Ashwal.
Mauritius is Familiar to Zircons Million Years of Age
Mauritius is not unfamiliar to such discoveries. The presence of zircon dating billions of years old in Mauritian beach sand was recorded back in 2013. However, this study was contested because it was argued that the mineral might not have come from underneath Mauritius as it could have been carried by the wind or through some other means. But, the new study counters that criticism, and supports the 2013 research, says Ashwal.
“The fact that we found the ancient zircons in rock (6-million-year-old trachyte), corroborates the previous study and refutes any suggestion of wind-blown, wave-transported or pumice-rafted zircons for explaining the earlier results,” says Ashwal.
More Lost Worlds In Indian Ocean
The piece of the lost continent under Mauritius would also not be the only one. Ashwal and his team believe that there might be more chunks of land (collectively known as Mauritia) from Gondwanaland in the Indian Ocean.
“According to the new results, this break-up did not involve a simple splitting of the ancient super-continent of Gondwana, but rather, a complex splintering took place with fragments of continental crust of variable sizes left adrift within the evolving Indian Ocean basin,” explains Ashwal.