Indian Ocean topography
© Seeker
Indian Ocean topography shows Mauritius as part of a chain of progressively older volcanoes that extend from the active hot-spot of Réunion toward the 65-million-year-old Deccan Traps in India.
A piece of an ancient continent, running from India to Madagascar, has been discovered under the tiny island of Mauritius off the East Coast of Africa.

The "lost continent" was formed in the breakup of the supercontinent, Gondwana, which began pulling apart about 200 million years ago. The small piece of crust was later covered by lava from volcanic eruptions on the island, researchers said, after the breakup of Africa, India, Australia and Antarctica, which formed the Indian Ocean.

The scientists, who published the study in the journal Nature Communications, said there are many pieces of the undiscovered continent, which they call Mauritia, found around the Indian Ocean, from the breakup of Gondwana.

"According to the new results, this break-up did not involve a simple splitting of the ancient super-continent of Gondwana," said Wits University geologist Lewis Ashwal, in a statement. "But rather, a complex splintering took place with fragments of continental crust of variable sizes left adrift within the evolving Indian Ocean basin."

Prof. Lewis D. Ashwal
© Susan Webb/Wits University
Lead author Prof. Lewis D. Ashwal studying an outcropping of trachyte rocks in Mauritius. Such samples are about 6 million years old, but surprisingly contain zircon grains as old as 3000 million years.
The scientists, by studying the mineral zircon, which is emitted by lava during eruptions, found an odd contradiction that suggested the minerals in rock samples being studied couldn't have originated from the island.

"Earth is made up of two parts — continents, which are old, and oceans, which are 'young,'" Ashwal said. "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. Mauritius is an island, and there is no rock older than 9 million years old on the island. However... we have found zircons [minerals found mainly in granite from the continents] that are as old as 3 billion years," in 6-million-year-old, igneous volcanic rock called trachyte.

Earlier studies found zircon in beach sand on Mauritius that some argued might have been blown onto the island, or carried from other parts of the world stuck to car tires or people's 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 said.