Ancient Micro-Continent Found Beneath Indian Ocean
Scientists have discovered fragments of an ancient micro-continent that lies buried in the Indian Ocean.
The continent fragment, which scientists have named as Mauritia, detached about 60 million years ago when India and Madagascar drifted apart. A team of international researchers have now found evidence that the micro-continent is hidden beneath the island of Mauritius.
About 750 million years ago, most of the Earth's landmass was gathered into a single supercontinent called Rodinia. Although they migrated to their current positions separated by thousands of miles of ocean, India was once located next to Madagascar some 85 million years ago.
"Break-up of continents is linked to mantle plumes. Bubbles of hot rock rise from the deep mantle and soften the tectonic plates from below until the plates break apart at the hotspots," according to a report by Helmholtz Association of German Research Centres.
The research team reconstructed plate tectonics, which suggested that the micro-continent Mauritia was once sandwiched between India and Madagascar.
Researchers also analyzed sand grains found on the beaches of the Mauritius island. To determine the age of the grains, the research team measured the balance of lead and uranium isotopes. They found that the grains dated back to about nine million years ago, but the minerals in them were much older, reports BBC.
The sand grains contained zircons aged between 1,970 and 600 million years ago. "We found zircons that we extracted from the beach sands, and these are something you typically find in a continental crust. They are very old in age," professor Trond Torsvik, from the University of Oslo, Norway, told the BBC.
Researchers believe that lava sand grains are from fragments of continental crust beneath Mauritius that could have been brought up to the surface of the island during a volcanic eruption. They think that at the time when India and Madagascar were drifting apart, this piece of continental crust would have got detached, and ultimately sunk beneath the waves.
The details of the study are published in the journal Nature Geoscience.